In the laboratory a student uses a "coffee cup" calorimeter to determine the specific heat of a metal.

She heats 19.5 grams of tungsten to 97.80°C and then drops it into a cup containing 78.3 grams of water at 22.58°C. She measures the final temperature to be 23.20°C.

Assuming that all of the heat is transferred to the water, she calculates the specific heat of tungsten to be J/g°C.

Answers

Answer 1

Answer : The specific heat of tungsten is, [tex]0.139J/g^oC[/tex]

Explanation :

In this problem we assumed that heat given by the hot body is equal to the heat taken by the cold body.

[tex]q_1=-q_2[/tex]

[tex]m_1\times c_1\times (T_f-T_1)=-m_2\times c_2\times (T_f-T_2)[/tex]

where,

[tex]c_1[/tex] = specific heat of tungsten = ?

[tex]c_2[/tex] = specific heat of water = [tex]4.18J/g^oC[/tex]

[tex]m_1[/tex] = mass of tungsten = 19.5 g

[tex]m_2[/tex] = mass of water = 78.5 g

[tex]T_f[/tex] = final temperature = [tex]23.20^oC[/tex]

[tex]T_1[/tex] = initial temperature of tungsten = [tex]97.80^oC[/tex]

[tex]T_2[/tex] = initial temperature of water = [tex]22.58^oC[/tex]

Now put all the given values in the above formula, we get

[tex]19.5g\times c_1\times (23.20-97.80)^oC=-78.5g\times 4.18J/g^oC\times (23.20-22.58)^oC[/tex]

[tex]c_1=0.139J/g^oC[/tex]

Therefore, the specific heat of tungsten is, [tex]0.139J/g^oC[/tex]


Related Questions

Which of the following statements about the kinetic molecular theory are not correct?
A. The combined volume of all the molecules of the gas is negligible relative to the total volume in which the gas is contained
B. Gases consist of molecules that are in continuous, random motion
C. The average kinetic energy of the molecules is not related to the absolute temperature
D. Attractive and repulsive forces between gas molecules are negligible

Answers

Answer:

The false statement is: (C) The average kinetic energy of the molecules is not related to the absolute temperature

Explanation:

According to the Kinetic Theory of Gases, gases are composed of small fast moving particles that are in constant random motion. These gaseous particles are known as molecules.

It is assumed that the mass of all the gaseous molecules is the same and the intermolecular interactions (attractive or repulsive) are negligible.

Also, the total volume of all the gaseous molecules is considered to be negligible as compared to the volume of the container.

According to this theory, average kinetic energy (K) of the gaseous particles is directly proportional to the absolute temperature (T) of the gas, by the equation:

[tex]K = \frac{3}{2}k_{b}T[/tex]

Here, [tex]k_{b}[/tex] is the Boltzmann constant

Therefore, the false statement about the kinetic molecular theory is (C)

Final answer:

Statement C, which suggests that the average kinetic energy of the molecules is not related to the absolute temperature, is incorrect.

Explanation:

The question is focused on the Kinetic Molecular Theory, which primarily has four postulates that describe the behavior of gases. The incorrect statement in the list is the following:

The average kinetic energy of the molecules is not related to the absolute temperature

In reality, according to the Kinetic Molecular Theory, the average kinetic energy of gas particles is directly proportional to the absolute temperature. This means that as the temperature increases, the average kinetic energy of the gas particles also increases, and vice versa. Therefore, it's clear that the temperature and average kinetic energy are related, making statement C incorrect.

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The dissociation of sulfurous acid (H2SO3) in aqueous solution occurs as follows:
H2SO3 ---> H+ + HSO3-
HSO3- ---> H+ + SO32-
If .50 moles of sulfurous acid are dissolved to form a 1 L solution, which of the following concentrations will be LEAST at equilibrium?
A.) [H2SO3]
B.) [H+]
C.) [H3O+]
D.) [SO32-]

Answers

Answer:

The [SO₃²⁻]

Explanation:

From the first dissociation of sulfurous acid we have:

                         H₂SO₃(aq) ⇄ H⁺(aq) + HSO₃⁻(aq)

At equilibrium:  0.50M - x          x            x

The equilibrium constant (Ka₁) is:

[tex] K_{a1} = \frac{[H^{+}] [HSO_{3}^{-}]}{[H_{2}SO_{3}]} = \frac{x\cdot x}{0.5 - x} = \frac {x^{2}}{0.5 -x} [/tex]

With Ka₁= 1.5x10⁻² and solving the quadratic equation, we get the following HSO₃⁻ and H⁺ concentrations:

[tex] [HSO_{3}^{-}] = [H^{+}] = 7.94 \cdot 10^{-2}M [/tex]

Similarly, from the second dissociation of sulfurous acid we have:

                              HSO₃⁻(aq) ⇄ H⁺(aq) + SO₃²⁻(aq)

At equilibrium:  7.94x10⁻²M - x          x            x

The equilibrium constant (Ka₂) is:  

[tex] K_{a2} = \frac{[H^{+}] [SO_{3}^{2-}]}{[HSO_{3}^{-}]} = \frac{x^{2}}{7.94 \cdot 10^{-2} - x} [/tex]  

Using Ka₂= 6.3x10⁻⁸ and solving the quadratic equation, we get the following SO₃⁻ and H⁺ concentrations:

[tex] [SO_{3}^{2-}] = [H^{+}] = 7.07 \cdot 10^{-5}M [/tex]

Therefore, the final concentrations are:

[H₂SO₃] = 0.5M - 7.94x10⁻²M = 0.42M

[HSO₃⁻] = 7.94x10⁻²M - 7.07x10⁻⁵M = 7.93x10⁻²M

[SO₃²⁻] = 7.07x10⁻⁵M

[H⁺] = 7.94x10⁻²M + 7.07x10⁻⁵M = 7.95x10⁻²M

So, the lowest concentration at equilibrium is [SO₃²⁻] = 7.07x10⁻⁵M.

I hope it helps you!

When .50 moles of sulfurous acid are dissolved in a 1 L solution, the concentration that will be least at equilibrium is [H2SO3].

In the given equilibrium reactions, when .50 moles of sulfurous acid are dissolved in a 1 L solution, the concentration that will be LEAST at equilibrium is [H2SO3], which represents the original acid concentration.

What purpose do each of the following play in the isolation and purification of ethyl 3- hydroxybutanoate?
a. Filtration with filter aid
b. Extraction with 3 portions of diethyl ether
c. Anhydrous sodium sulfate
d. Evaporation in the hood

Answers

Explanation:

-Filter help — delete some big unreacted, undesirable species (norit is probably from what you are sorting through, its only carbon which cleans up things)

— extract with DCM because you are probably in an aqueous phase, and some butanoate is in it

- Anhydrous sodium absorbs excess of  water (dries the material)

-evaporation in the hood to clear the DCM and crystallize the product.

Which of the following best defines molar heat capacity. a. The quantity of heat required to lower the temperature of 1 liter of a substance by 1°C b.The quantity of heat required to raise the temperature of 1 gram of a substance by 1°F c. The quantity of heat required to raise the temperature of 1 gram of a substance by 1°C d, The quantity of heat required to raise the temperature of 1 mole of a substance by 1K

Answers

Answer:

d. The quantity of heat required to raise the temperature of 1 mole of a substance by 1K

Explanation:

Heat capacity is a physical property of matter that is defined as the quantity of heat supplied for a material to change in one unit its temperature. This heat depends of the amount of material.

For that reason, molar heat capacity is defined as:

d. The quantity of heat required to raise the temperature of 1 mole of a substance by 1K

Alluding molar to moles of a material or substance.

I hope it helps!

The K b Kb for an amine is 4.004 × 10 − 5 . 4.004×10−5. What percentage of the amine is protonated if the pH of a solution of the amine is 9.370 9.370 ? Assume that all OH − OH− came from the reaction of B with H 2 O . H2O. percentage protonated: %

Answers

Answer:

The percentage of amine is protonated is 63,07%

Explanation:

The reaction of an amine RNH₃ (weak base) with water is:

RNH₃ + H₂O ⇄ RNH₄⁺ + OH⁻

The kb is defined as:

[tex]kb = \frac{[RNH_{4}^+][OH^-]}{[NH_{3}]}[/tex]

As kb = 4,004x10⁻⁵ and [OH⁻] is [tex]10^{-(14-9,370)}=2,344x10^{-5}[/tex]:

[tex]4,004x10^{-5} = \frac{[RNH_{4}^+][2,34x10^{-5}]}{[NH_{3}]}[/tex]

1,708 = [RNH₄⁺] / [RNH₃] (1)

As the total amine is a 100%:

[RNH₄⁺] + [RNH₃] = 100% (2)

Replacing (1) in (2):

1,708 [RNH₃]+ [RNH₃] = 100%

2,708 [RNH₃] = 100%

[RNH₃] = 36,93%

Thus,

[RNH₄⁺] = 63,07%

The percentage of amine protonated is 63,07%

I hope it helps!

The percentage of the amine protonated at a pH of 9.370, with Kb of 4.004 × 10⁻⁵, is approximately 63%.

Use the relationship pKa + pKb = 14 to find the pKa of the amine's conjugate acid:

pKa = 14 - pKb

pKb = -log(Kb) = -log(4.004 × 10⁻⁵) = 4.397

pKa = 14 - 4.397 = 9.603

The Henderson-Hasselbalch equation can now be used to find the ratio of protonated to unprotonated forms:

pH = pKa + log([A⁻]/[HA])

9.370 = 9.603 + log([A⁻]/[HA])

-0.233 = log([A⁻]/[HA])

[A⁻]/[HA] = 10⁻⁰·²³³ ≈ 0.588

The fraction of the amine that is protonated ([HA]) can be found by considering:

fraction protonated ([HA]) = [HA] / ([HA] + [A⁻])

Let [HA] = x and [A⁻] = 0.588x, so:

fraction protonated ([HA]) = x / (x + 0.588x) = 1 / (1 + 0.588) ≈ 0.63

Therefore, the percentage protonated is approximately:

63%

Consider a beaker containing a saturated solution of PbI2 in equilibrium with undissolved PbI2(s).

(a) If solid KI is added to this solution, will the amount of solid PbI2 at the bottom of the beaker increase, decrease, or remain the same?
(b) Will the concentration of Pb^2+ ions in solution increase or decrease?
(c) Will the concentration of I- ions in solution increase or decrease?

Answers

Answer:

(a) Increase the solid  PbI₂ (s)

(b) Decrease  

(c) Increase

Explanation:

In this question  we are considering the effect of adding a common ion to an equilibrium.

The problem states that the saturated solution  of PbI₂ is at equilibrium with undissolved PbI₂ (s) :

PbI₂ (s)  ⇄     Pb²⁺+ 2 I⁻  

If we increase the concentration of I⁻ by adding the highly soluble KI , the equilibrium will react according to LeChatelier´s principle by decreasing the concentration of  Pb²⁺ precipitating some  Pb²⁺ until it reaches equilibrium again. With this in mind, lets answer the question:

(a) Increase the solid  PbI₂ (s)

(b) Decrease  

(c) Increase

The addition of KI in the solution increases the settling of lead iodide at the bottom, decreases the lead ions and increases the iodide ions in the solution.

What is a saturated solution?

The saturated solution has been given as the one in which the salt has been divided into maximum concentration.

The equilibrium reaction of lead iodide has been:

[tex]\rm PbI_2\;\rightleftharpoons Pb^2^+\;+2\;I^-[/tex]

The addition of KI increases the product concentration, and the lead iodide has been found to be settles in increased concentration in the bottom.

The addition of KI decreases the rate of formation of product, thus the ion of lead formation will be decreased in the reaction.

The concentration of iodide ions in the solution increases with the addition of KI with common ion effect.

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Which statement about boiling point is FALSE?

The boiling point is higher for compounds with a high viscosity.

The boiling point of a compound is an absolute constant.

The boiling point is higher for compounds with strong intermolecular forces.

The boiling point of a compound is higher for nonvolatile compounds.

All of the above statements are true.

Answers

Answer: The boiling point of water is an absolute constant

Explanation:

The boiling point of a compound is NOT an absolute constant. This is because at certain conditions such as a change in altitude, the boiling point of a compound changes.

As temperature increases, evaporation increases and vapour pressure increases. Compounds boils when vapour pressure equal to the atmospheric pressure.

At higher altitudes, atmospheric pressure is decreses.

When atmospheric pressure is decresed, the vapour pressure of the compound is lowered to reach boiling point. Therefore, the temperature needed for vapour pressure to equal atmospheric pressure is lower. The boiling point is lower at higher altitude.

Hence boiling point depends on atmospheric pressure

Final answer:

The boiling point of a compound is not an absolute constant.

Explanation:

The statement "The boiling point of a compound is an absolute constant" is FALSE.

The boiling point of a compound is affected by several factors, including intermolecular forces and molecular structure. Compounds with stronger intermolecular forces, such as hydrogen bonds, will generally have higher boiling points. Viscosity, which is the resistance of a liquid to flow, is not directly related to boiling point. Nonvolatile compounds, which do not easily evaporate, may have lower boiling points depending on their molecular structure.

Therefore, the correct statement is that the boiling point is not an absolute constant.

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The solubility of gold (III) chloride is 1.00x10^-4 g/L. What is the Ksp for AuCl3 (Molar Mass=303.3 g/mol)
A.) 1.00x10^-16
B.) 2.7x10^-15
C.) 1.2x10^-26
D.) 3.2x10^-25

Answers

Answer: The [tex]K_{sp}[/tex] of gold (III) chloride is [tex]3.2\times 10^{-25}[/tex]

Explanation:

We are given:

Solubility of gold (III) chloride = [tex]1.00\times 10^{-4}g/L[/tex]

Molar mass of gold (III) chloride = 303.3 g/mol

To calculate the solubility in mol/L, we divide the given solubility (in g/L) with molar mass, we get:

[tex]\text{Solubility (in mol/L)}=\frac{\text{Solubilty (in g/L)}}{\text{Molar mass}}[/tex]

Putting values in above equation, we get:

[tex]\text{Solubility of gold (III) chloride (in mol/L)}=\frac{1.00\times 10^{-4}g/L}{303.3g/mol}\\\\\text{Solubility of gold (III) chloride (in mol/L)}=3.29\times 10^{-7}mol/L[/tex]

The balanced equilibrium reaction for the ionization of gold (III) chloride follows:

[tex]AuCl_3\rightleftharpoons Au^{3+}+3Cl^-[/tex]

                s       3s

The expression for solubility constant for this reaction will be:

[tex]K_{sp}=[Au^{3+}][Cl^-]^3[/tex]

We are given:

[tex]s=3.29\times 10^{-7}mol/L[/tex]

Putting values in above equation, we get:

[tex]K_{sp}=(s)\times (3s)^3\\\\K_{sp}=9s^4\\\\K_{sp}=9\times (3.29\times 10^{-7})^4[/tex][tex]K_{sp}=(s)\times (3s)^3\\\\K_{sp}=27s^4\\\\K_{sp}=27\times (3.29\times 10^{-7})^4=3.2\times 10^{-25}[/tex]

Hence, the [tex]K_{sp}[/tex] of gold (III) chloride is [tex]3.2\times 10^{-25}[/tex]

Final answer:

The Ksp of AuCl3, calculated from its solubility and molar mass, is 1.2x10^-26.

Explanation:

In order to calculate the Ksp for AuCl3, we first need to convert the solubility from g/L to mol/L. We do this by dividing the given solubility (1.00x10^-4 g/L) by the molar mass of AuCl3 (303.3 g/mol). This gives us a molar solubility of 3.3x10^-7 mol/L. The dissolution reaction of AuCl3 can be represented as follows: AuCl3(s) -> Au3+(aq) + 3Cl-(aq). The solubility product (Ksp) is then obtained by multiplying the concentration of each ion raised to the power of its stoichiometric coefficient in the balanced equation. This gives Ksp=Au3+ (aq) * Cl-(aq)^3 = (3.3x10^-7)^4 = 1.2x10^-26, hence, the answer is option C.) 1.2x10^-26.

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Combustion of hydrocarbons such as butane () produces carbon dioxide, a "greenhouse gas." Greenhouse gases in the Earth's atmosphere can trap the Sun's heat, raising the average temperature of the Earth. For this reason there has been a great deal of international discussion about whether to regulate the production of carbon dioxide. Write a balanced chemical equation, including physical state symbols, for the combustion of gaseous butane into gaseous carbon dioxide and gaseous water. 2. Suppose 0.360 kg of butane are burned in air at a pressure of exactly 1 atm and a temperature of 20.0 °C. Calculate the volume of carbon dioxide gas that is produced Be sure your answer has the correct number of significant digits.

Answers

The balanced chemical equation for the combustion of butane is correct. Converting the mass of butane to moles and using the mole ratio, the volume of carbon dioxide produced is approximately 596 liters, as calculated using the ideal gas law.

Combustion of Butane and its Volume Calculation:

1. Balanced Chemical Equation:

The provided equation is correct:

C₄H₁₀ + ¹³/₂O₂ → 4CO₂ + 5H₂O

It is balanced because it has the same number of atoms of each element on both sides of the equation.

2. Volume of Carbon Dioxide Produced:

a) Converting Mass of Butane to Moles:

The mass of butane (0.360 kg) to moles (6.19 mol) using the following formula:

moles = mass / molar mass

The molar mass of butane is approximately 58.12 g/mol.

b) Mole Ratio and CO₂ Production:

The balanced equation tells us that 1 mole of butane reacts with 13/2 moles of oxygen to produce 4 moles of carbon dioxide. Therefore, the 6.19 moles of butane will produce:

6.19 mol butane * (4 mol CO₂ / 1 mol butane) = 24.76 mol CO₂

c) Ideal Gas Law and Volume Calculation:

The ideal gas law relates the volume (V), pressure (P), temperature (T), and number of moles (n) of a gas:

V = nRT/P

where:

R is the gas constant (0.08206 L atm/mol K)

T is the temperature in Kelvin (293.15 K)

P is the pressure in atm (1 atm)

Plugging in the values:

V = 24.76 mol * 0.08206 L atm/mol K * 293.15 K / 1 atm ≈ 596 L

Therefore, the volume of carbon dioxide produced is approximately 596 liters.

The reaction of 50 mL of Cl2 gas with 50 mL of C2H4 gas via the equation: Cl2 (g) + C2H4 (g) → C2H4Cl2 (g) will produce a total of ________ mL of products if pressure and temperature are kept constant.

Answers

Final answer:

The reaction of 50 mL of Cl2 gas with 50 mL of C2H4 gas will produce 50 mL of C2H4Cl2 gas.

Explanation:

In this reaction, the balanced equation tells us that 1 mole of Cl2 reacts with 1 mole of C2H4 to produce 1 mole of C2H4Cl2. Since the volumes of the gases are given, we can assume that the gases are at the same pressure and temperature. This means that the ratio of the volumes of the gases is the same as the ratio of the moles of the gases.

Therefore, if we have 50 mL of Cl2 gas and 50 mL of C2H4 gas, we would have 1 mole of Cl2 and 1 mole of C2H4. The reaction would produce 1 mole of C2H4Cl2, which is equivalent to 50 mL of C2H4Cl2 gas.

Hence, the total volume of products produced in this reaction would be 50 mL.

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Final answer:

The reaction of 50 mL of Cl₂ gas with 50 mL of C₂H₄ gas under constant pressure and temperature produces 50 mL of C₂H₄Cl₂ gas as the product, following Avogadro's law.

Explanation:

The question revolves around a chemical reaction where Cl₂ gas reacts with C₂H₄ gas to produce C₂H₄Cl₂ gas. According to Avogadro's law, at constant temperature and pressure, equal volumes of gases contain the same number of molecules. Hence, the volumes of gaseous reactants and products should be in the same ratio as their coefficients in the balanced chemical equation.

In this case, the chemical equation is:

Cl₂ (g) + C₂H₄ (g) → C₂H₄Cl₂ (g)

Each reactant has a coefficient of 1, indicating that they react on a one-to-one volume basis. This means that 50 mL of Cl₂ reacts with 50 mL of C₂H₄ to produce 50 mL of C₂H₄Cl₂. Since temperature and pressure are held constant, by Avogadro's principle, the volume of the products is the same as the volume of the reactants.

Therefore, the reaction of 50 mL of Cl₂ gas with 50 mL of C₂H₄ gas will produce a total of 50 mL of C₂H₄Cl₂ gas as the product.

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What is the coordination number for each of the following complexes?A) [Fe(gly)2(H2O)2]+B) [Pb(EDTA)]2−C) [Pt(NH3)4]2+D) Na[Au(CN)2]

Answers

Answer:

A) 6

B) 6

C) 4

E) 1

Explanation:

Coordination number, also called Ligancy, the number of atoms, ions, or molecules bound to the metal atom in a complex ion

A) [Fe(gly)2(H2O)2]

Gly = the aminoacid glycin, and works as a  bidentate ligand,Bidentate ligands bind through two donor sites. Bidentate means "two-toothed".  It can bind to a metal via two donor atoms at once.

This makes the coordination number = 6

B) [Pb(EDTA)]2

EDTA is a hexadentate ligand and forms very stable complexes.

EDTA forms 6 bonds to the Pb atom (2 Pb-N bonds and 4 Pb-O bonds). The coordination number = 6.

C) [Pt(NH3)4]2+

It's a squareplanar complex with coordination number = 4 because 4 bindings with NH3

D) Na[Au(CN)2]

Cyanide binds only to 1 Au- atom. The coordination number = 1

A) [tex][Fe(gly)2(H2O)_2]^+[/tex]: Coordination number is 6.

B)[tex][Pb(EDTA)]_2[/tex]−: Coordination number is 6.

C) [tex][Pt(NH_3)_4]^2+[/tex]: Coordination number is 4.

D) [tex]Na[Au(CN)_2]:[/tex] Coordination number is 2.

The coordination numbers for each of the given complexes are as follows:

A) [tex][Fe(gly)2(H2O)2]+[/tex]: The coordination number of the iron (Fe) ion in this complex is 6. This is because there are two glycine (gly) ligands and two water (H2O) molecules coordinated to the iron ion. Each glycine is bidentate, meaning it binds to the iron ion with two donor atoms (usually nitrogen and oxygen), contributing a total of four donor atoms. The two water molecules each provide one donor atom (oxygen). Thus, the total number of donor atoms around the iron ion is 6, giving it a coordination number of 6.

 B) [tex][Pb(EDTA)]2[/tex]: The coordination number of the lead (Pb) ion in this complex is 6. Ethylenediaminetetraacetic acid (EDTA) is a hexadentate ligand, meaning it can bind to a metal ion with all six of its donor atoms (four oxygens and two nitrogens). Since EDTA is fully deprotonated in this complex, it forms a negatively charged species that can wrap around the lead ion, resulting in a coordination number of 6.

 C) [tex][Pt(NH_3)_4]^2+:[/tex] The coordination number of the platinum (Pt) ion in this complex is 4. There are four ammonia (NH3) molecules coordinated to the platinum ion, each acting as a monodentate ligand and providing one donor atom (nitrogen). Therefore, the platinum ion is surrounded by four donor atoms, giving it a coordination number of 4.

 D) [tex]Na[Au(CN)_2][/tex]: The coordination number of the gold (Au) ion in this complex is 2. There are two cyanide (CN) ligands coordinated to the gold ion, each acting as a monodentate ligand and providing one donor atom (carbon). Thus, the gold ion is surrounded by two donor atoms, giving it a coordination number of 2.

 To summarize:

A) [tex][Fe(gly)2(H2O)_2]^+[/tex]: Coordination number is 6.

B)[tex][Pb(EDTA)]_2[/tex]−: Coordination number is 6.

C) [tex][Pt(NH_3)_4]^2+[/tex]: Coordination number is 4.

D) [tex]Na[Au(CN)_2]:[/tex] Coordination number is 2.

A strain of Escherichia coli has been genetically engineered to produce human protein. A batch culture is started by inoculating 12 g of cells into a 100-litre bubble column fermenter containing 10 g 1^- 1 glucose. The culture does not exhibit a lag phase. The maximum specific growth rate of the cells is 0.9 h^-1; the biomass yield from glucose is 0.575 g g^-1
1. Estimate the time required to reach stationary phase.
2. What will be the final cell density if the fermentation is stopped after only 70% of the substrate is consumed?

Answers

Answer:

1. 4.32 h

2. 4.12 g/L

Explanation:

1. For a batch culture, the time (tb) can be calculated by:

tb =  ln (X/X0)/μmax

Where X0 is the initial mass concentration of the cells (12 g/100L = 0.12 g/L), X is the mass concentration of the cells at tb, and μmax is the maximum specific growth rate of the cells.

The biomass yield (Y) is:

Y = (X - X0)/ (S0 - S)

Where S is the mass concentration of the substrate at tb and S0 the initial mass concentration of the substrate (glucose in this case).

Reorganizing:

X = Y*(S0 -S) + X0

Let's assume that at the stationary state all substrate was consumed, so S = 0.

tb = ln[(YS0 + X0)/X0)]/μmax

tb = ln[(0.575*10 + 0.12)/0.12]/0.9

tb = 4.32 h

2.  If 70% of the substrate is consumed, S = 10 - 0.7*10 = 3 g/L

tb = ln[(0.575*(10-3) + 0.12)/0.12]/0.9

tb = 3.93 h

The initial concentration is X0 = 0.12 g/L, the X:

tb =  ln (X/X0)/μmax

3.93 = ln(X/0.12)/0.9

ln(X/0.12) = 3.537

X/0.12 = [tex]e^{3.537}[/tex]

X/0.12 = 34.36

X = 4.12 g/L

Answer:

a) to = 4.3 h

b) xf = 4.1 g/L

Explanation:

We have the following data:

So = 10 g*L^-1 = initial concentration

Ys = biomass yield = 0.575 g*g^-1

umax = maximum specific growth rate = 0.9 h^-1

The initial cell concentration is equal to:

xo = 12 g/100 L = 0.12 g/L

a) The batch time it takes to reach the stationary phase equals:

to = (1/umax)*ln(1 + (Ys*(so-sf)/xo))) = (1/0.9)*ln(1+(0.575*(10-0))/0.12)))) = 4.3 h

b) Since the fermentation stops after consuming only 70% of the glucose, we have the following:

sf = (1-07)*so = 0.3*10 = 3 g/L

tb = (1/0.9)*ln(1+(0.575*(10-3))/(0.12)))) = 3.94 h

Finally, the final cell concentration can be found by the following equation:

xf = xo*e^(umax * tb) = 0.12 * e^(0.9 * 3.94) = 4.1 g/L

(b) Once the ionic solid has dissolved, the anion that is formed is able to react as a base, with water as the acid. Write the net acid-base reaction that occurs when dissolved NaC2H3O2 reacts with water. (Use the lowest possible coefficients. Omit states-of-matter in your answer.)
(e) Write the net acid-base reaction that occurs when HC2H3O2 is added to water.
chemPadHelp
HC2H3O2 + H2O → H3O+ + C2H3O2-
Correct.
(f) What is the relative Ka value for this reaction?
Ka << 1
Ka ≈ 1
Ka >> 1Correct: Your answer is correct.
(g) Which species are present in the greatest concentration? (Select all that apply.) --I need b and g
weak acid molecules
hydronium ions
water molecules
conjugate base ions

Answers

Answer:

b C₂H₃O₂⁻ + H₂O ⇄ HC₂H₃O₂ + OH⁻

e HC₂H₃O₂ + H₂O ⇄ H₃O⁺ + C₂H₃O₂⁻

f ka<<1

g. Weak acid molecules and water molecules

Explanation:

The water molecule could act as a base and as an acid, a molecule that have this property is called as amphoteric.

b The salt NaC₂H₃O₂ is dissolved in water as Na⁺ and C₂H₃O₂⁻. The reaction of the anion with water is:

C₂H₃O₂⁻ + H₂O ⇄ HC₂H₃O₂ + OH⁻

Where the C₂H₃O₂⁻ is the base and water is the acid.

e. The reaction of HC₂H₃O₂ (acid) with water (base), produce:

HC₂H₃O₂ + H₂O ⇄ H₃O⁺ + C₂H₃O₂⁻

f. As the acetic acid (HC₂H₃O₂) is a week acid, the dissociation in C₂H₃O₂⁻ is not complete, that means that ka<<1

g. The ka for this reaction is 1,8x10⁻⁵, that means that there are more weak acid molecules (HC₂H₃O₂) than conjugate base ions. Also, the water molecules will be in higher proportion than hydronium ions.

I hope it helps!

HC2H3O2 is a weak acid so it dissociates to a small extent in solution.

When NaC2H3O2 is dissolved in water, the following reaction occurs;

[tex]NaC2H3O2(aq) ---->Na^+(aq) + C2H3O2-(aq)[/tex]

The ion combines with water as follows;

[tex]C2H3O2-(aq) + H2O(l) -----> HC2H3O2(aq) + OH-(aq)[/tex]

When  HC2H3O2 is added to water, the following reaction occurs;

[tex]HC2H3O2(aq) + H2O(l) -----> H3O+(aq) + C2H3O2-(aq)[/tex]

We must note that HC2H3O2 is a weak acid. Weak acids only dissociate to a small extent in water therefore Ka << 1.

Since Ka << 1, it the follows that weak acid molecules and water molecules are present in the greatest concentration in solution because HC2H3O2 only dissociates to a very small extent.

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The synthesis of methanol from carbon monoxide and hydrogen gas is described by the following chemical equation:
CO(g)+2H2(g)⇌CH3OH(g)
The equilibrium constant for this reaction at 25 ∘C is Kc=2.3×104. In this tutorial, you will use the equilibrium-constant expression to find the concentration of methanol at equilibrium, given the concentration of the reactants.

Determine the expression for the equilibrium constant, Kc, for the reaction by identifying which terms will be in the numerator and denominator:

The equilibrium-constant expression is a mathematical equation that can be rearranged to solve for any of the variables in it. Rearrange the equilibrium-constant expression to solve for [CH3OH].
[CH3OH]=[CH3OH]=
1Kc[CO][H2]2
Kc[CO][H2]2
Kc[CO][H2]2
[CO][H2]2Kc

Answers

Answer:

The expression will be given as:

[tex][CH_3OH]=K_c\times [CO]\times [H_2]^2[/tex]

Explanation:

Equilibrium constant is defined as the ratio of concentration of products to the concentration of reactants each raised to the power their stoichiometric ratios. It is expressed as [tex]K_{c}[/tex]

[tex]aA+bB\rightleftharpoons cC+dD[/tex]

[tex]K_{c}=\frac{[C]^c[D]^d}{[A]^a[B]^b}[/tex]

[tex]CO(g)+2H_2(g)[/tex] ⇌ [tex]CH_3OH(g)[/tex]

The equilibrium-constant expression for the given reaction  is given by:

[tex]K_{c}=\frac{[CH_3OH]}{[CO][H_2]^2}[/tex]

If we are given with equilibrium constant and equilibrium concentration of carbon monoxide and hydrogen gas we can determine the concentration of methanol at equilibrium.

The expression will be given as:

[tex][CH_3OH]=K_c\times [CO]\times [H_2]^2[/tex]

Saponification is a chemical reaction _____. A. due to the presence of a strong organic acid. B. that results in an alcohol and a carboxylic acid. C. that explains why soap does not wash off easily in hard water. D. that always results directly in a soap.

Answers

Answer:

that results in an alcohol and a carboxylic acid.

Explanation:

Saponification is a chemical reaction process of alkaline hydrolysis of esters(R'COOR group) by which soap is obtained.

For Example, when a base such as sodium hydroxide [NaOH]  is used to hydrolyze an ester, the products are a carboxylate salt and an alcohol. Because soaps are prepared by the alkaline hydrolysis of fats and oils.

In a saponification reaction, alkaline hydrolysis of fats and oils with sodium hydroxide  yields propane-1,2,3-triol and the corresponding sodium salts of the component fatty acids.

i.e  Fat or oil + caustic alkali ⇒ Soap + propane-1,2,3-triol

As a specific example, ethyl acetate and NaOH react to form sodium acetate and ethanol:

The reaction goes to completion in the image below:

A 1.10 kg piece of granite with a specific heat of 0.803 J g-1 °C-1 and a temperature of 87.3 °C is placed into 2.00 L of water at 20.3 °C. When the granite and water come to the same temperature, what will the temperature be?

Answers

The final temperature of the granite and the water will be 26.6 °C.

Heat energy

In a mixture between two substances of different temperatures, there is heat transfer, in which the one with a lower temperature receives this heat and the one with a higher temperature loses the heat.

In a system, the value of heat lost and received is equal.

This heat is represented by the following expression:

                                         [tex]Q = m \times c \times T[/tex]

The value of heat is given in calories, the value of temperature is given in celsius and the value of mass is given in grams

Thus, to find the value of the final temperature of the mixture, it is enough to equate the heat of the two substances.

                     [tex]1100 \times (\frac{0.803}{4,18}) \times (t_{f} - 83.7) = 2000 \times 1 \times (t_{f} - 20.3)[/tex]

                               [tex]220 (t_{f} - 83.7) = 2000 (t_{f} - 20.3)[/tex]

As the value of the granite final temperature is lower than the initial temperature, the result of the temperature variation would be negative, so the signs of the expression can be changed.

                                 [tex]18414 - 220 t_{f} = 2000 t_{f} - 40600[/tex]

                                         [tex]2220 t_{f} = 59,014[/tex]

                                              [tex]t_{f} = 26.6[/tex]

So, the final temperature of the granite and the water will be 26.6 °C.

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Final answer:

Using conservation of energy, the final equilibrium temperature of the granite and water system can be calculated by setting the heat lost by granite equal to the heat gained by water and solving for the final temperature.

Explanation:

The question is asking for the final equilibrium temperature of a two-part system initially at different temperatures when they are put in contact. This is a problem that can be solved using the concept of heat transfer and the principle of conservation of energy. The heat lost by the hot granite will equal the heat gained by the cooler water until thermal equilibrium is reached.

Using the specific heats of granite and water, and their masses and initial temperatures, we set up the equation based on the principle that heat lost = heat gained:

m1c1(Tfinal - T1(initial)) = m2c2(T2(initial) - Tfinal)

Where m1 and m2 are the masses of granite and water, c1 and c2 are their specific heats, Tfinal is the final equilibrium temperature and T1(initial) and T2(initial) are the initial temperatures of granite and water, respectively. You'll need to convert the mass of the granite to grams, as the specific heat is given in grams, and use the specific heat of water (4.184 J/g°C).

Then you can solve for Tfinal to find the temperature at which the granite and water reach equilibrium.

Galvanized nails are iron nails that have been plated with zinc to prevent rusting. The relevant reaction is

Zn2+(aq)+2e−→Zn(s)

For a large batch of nails, a manufacturer needs to plate a total zinc mass of 3.30 kg on the surface to get adequate coverage.

Part A

How many moles of zinc are in 3.30 kg of zinc?

Express your answer to three significant figures and include the appropriate units.

50.5 mol
SubmitHintsMy AnswersGive UpReview Part

Correct

Significant Figures Feedback: Your answer 50.47mol was either rounded differently or used a different number of significant figures than required for this part.

Answers

Answer:

50. 5mol

Explanation:

The mass of Zinc required = 3.30 kg = 3300 grams

The relation between moles and mass is:

[tex]moles=\frac{mass}{atomicmass}[/tex]

Atomic mass of Zinc = 65.38g/mol

[tex]molesofZinc=\frac{3300}{65.38}[/tex]

[tex]molesofzinc=50.47mol[/tex]

The answer to three significant figures will be 50.5 mol

Final answer:

To find the number of moles of zinc in 3.30 kg of zinc, divide the mass in grams by the molar mass of zinc. The number of moles of zinc is 50.5 mol.

Explanation:

To find the number of moles of zinc in 3.30 kg of zinc, we can use the molar mass of zinc to convert the mass to moles. The molar mass of zinc (Zn) is 65.38 g/mol. First, we convert the mass from kg to g by multiplying by 1000:

3.30 kg × 1000 g/kg = 3300 g

Then, we divide the mass in grams by the molar mass to get the number of moles:

3300 g / 65.38 g/mol = 50.5 mol

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Calculate the standard enthalpy change for the reaction at 25 ∘ 25 ∘ C. Standard enthalpy of formation values can be found in this list of thermodynamic properties. Mg ( OH ) 2 ( s ) + 2 HCl ( g ) ⟶ MgCl 2 ( s ) + 2 H 2 O ( g )

Answers

Answer: The standard enthalpy change of the reaction is coming out to be -16.3 kJ

Explanation:

Enthalpy change is defined as the difference in enthalpies of all the product and the reactants each multiplied with their respective number of moles. It is represented as [tex]\Delta H[/tex]

The equation used to calculate enthalpy change is of a reaction is:  

[tex]\Delta H_{rxn}=\sum [n\times \Delta H_f(product)]-\sum [n\times \Delta H_f(reactant)][/tex]

For the given chemical reaction:

[tex]Mg(OH)_2(s)+2HCl(g)\rightarrow MgCl_2(s)+2H_2O(g)[/tex]

The equation for the enthalpy change of the above reaction is:

[tex]\Delta H_{rxn}=[(1\times \Delta H_f_{(MgCl_2(s))})+(2\times \Delta H_f_{(H_2O(g))})]-[(1\times \Delta H_f_{(Mg(OH)_2(s))})+(2\times \Delta H_f_{(HCl(g))})][/tex]

We are given:

[tex]\Delta H_f_{(Mg(OH)_2(s))}=-924.5kJ/mol\\\Delta H_f_{(HCl(g))}=-92.30kJ/mol\\\Delta H_f_{(MgCl_2(s))}=-641.8kJ/mol\\\Delta H_f_{(H_2O(g))}=-241.8kJ/mol[/tex]

Putting values in above equation, we get:

[tex]\Delta H_{rxn}=[(1\times (-641.8))+(2\times (-241.8))]-[(1\times (-924.5))+(2\times (-92.30))]\\\\\Delta H_{rxn}=-16.3kJ[/tex]

Hence, the standard enthalpy change of the reaction is coming out to be -16.3 kJ

Final answer:

To calculate the standard enthalpy change for the given reaction, use the standard enthalpy of formation values for the reactants and products. Calculate the enthalpy change for the formation of each compound using their respective standard enthalpy of formation values. Then, calculate the overall enthalpy change for the reaction by subtracting the sum of the enthalpy changes for the reactants from the sum of the enthalpy changes for the products. Round the result to the appropriate number of significant figures.

Explanation:Standard Enthalpy of Formation:

The standard enthalpy change for a reaction can be calculated using the standard enthalpy of formation values. For the given reaction, Mg(OH)2(s) + 2 HCl(g) ⟶ MgCl2(s) + 2 H2O(g), we need to use the standard enthalpy of formation values for the reactants and products.

Step 1: Calculate the enthalpy change for the formation of Mg(OH)2(s) using its standard enthalpy of formation value.

Step 2: Calculate the enthalpy change for the formation of MgCl2(s) using its standard enthalpy of formation value.

Step 3: Calculate the enthalpy change for the formation of H2O(g) using its standard enthalpy of formation value.

Step 4: Calculate the overall enthalpy change for the reaction by subtracting the sum of the enthalpy changes for the reactants from the sum of the enthalpy changes for the products.

Step 5: Round the result to the appropriate number of significant figures.

Answer: The standard enthalpy change for the given reaction at 25°C can be calculated using the standard enthalpy of formation values for the reactants and products.

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The value of Ka for nitrous acid (HNO2) at 25 ∘C is 4.5×10−4 .a. Write the chemical equation for the equilibrium that corresponds to Ka1. H+(aq)+NO−2(aq)⇌HNO2(aq)2. HNO2(aq)⇌H+(aq)+NO−2(aq)3. HNO2(aq)⇌H−(aq)+NO+2(aq)4. HNO2(aq)+H+(aq)⇌H2NO+2(aq)5. HNO2(aq)+H−(aq)⇌H2NO+2(aq)​b. By using the value of Ka , calculate ΔG∘ for the dissociation of nitrous acid in aqueous solution. c. What is the value of ΔG at equilibrium? d. What is the value of ΔG when [H+] = 5.9×10−2 M , [NO−2] = 6.7×10−4 M , and [HNO2] = 0.21 M ?

Answers

Answers and Explanation:

a)- The chemical equation for the corresponden equilibrium of Ka1 is:

2. HNO2(aq)⇌H+(aq)+NO−2

Because Ka1 correspond to a dissociation equilibrium. Nitrous acid (HNO₂) losses a proton (H⁺) and gives the monovalent anion NO₂⁻.

b)- The relation between Ka and the free energy change (ΔG) is given by the following equation:

ΔG= ΔGº + RT ln Q

Where T is the temperature (T= 25ºc= 298 K) and R is the gases constant (8.314 J/K.mol)

At the equilibrium: ΔG=0 and Q= Ka. So, we can calculate ΔGº by introducing the value of Ka:

⇒ 0 = ΔGº + RT ln Ka

   ΔGº= - RT ln Ka

   ΔGº= -8.314 J/K.mol x 298 K x ln (4.5 10⁻⁴)

  ΔGº= 19092.8 J/mol

c)- According to the previous demonstation, at equilibrium ΔG= 0.

d)- In a non-equilibrium condition, we have Q which is calculated with the concentrations of products and reactions in a non equilibrium state:

ΔG= ΔGº + RT ln Q

Q= ((H⁺) (NO₂⁻))/(HNO₂)

Q= ( (5.9 10⁻² M) x (6.7 10⁻⁴ M) ) / (0.21 M)

Q= 1.88 10⁻⁴

We know that   ΔGº= 19092.8 J/mol, so:

ΔG= ΔGº + RT ln Q

ΔG= 19092.8 J/mol + (8.314 J/K.mol x 298 K x ln (1.88 10⁻⁴)

ΔG= -2162.4 J/mol

Notice that ΔG<0, so the process is spontaneous in that direction.

HNO2 is a weak acid whose dissociation occurs as follows;  HNO2 (aq)    ⇋       H+ (aq)  +      NO2- (aq)

The equation for the dissociation of HNO2 is;

           HNO2 (aq)    ⇋       H+ (aq)  +      NO2- (aq)

We can use the value of Ka to find the  ΔG∘ for the dissociation of nitrous acid in aqueous solution as follows;

ΔG∘ = -RTlnKa

Where;

R = Gas constant = 8.314 J/K. mol

Ka = Acid dissociation constant = 4.5×10^−4

T = temperature = 25 ∘C or 298 K

Substituting values;

ΔG∘ = -(8.314 J/K. mol × 298 K × ln 4.5×10^−4)

ΔG∘ = 19.1 KJ/mol

Given that;

Q = [ H+] [NO2- ]/[HNO2]

[ H+] =  5.9×10−2 M

[NO2- ] = 6.7×10−4 M

[HNO2] = 0.21 M

Q = [5.9×10−2 M] [6.7×10−4 M]/[0.21 M]

Q = 1.88 × 10^−4

From the formula;

ΔG = ΔG∘ + RTlnQ

ΔG =  19.1  KJ/mol + (8.314 J/K. mol  ×  298 K ×  ln 1.88 × 10^−4)

ΔG = -2.15 KJ/mol

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From these two reactions at 298 K, V2O3(s) + 3CO(g) → 2V(s) + 3CO2(g); ΔH° = 369.8 kJ; ΔS° = 8.3 J/K V2O5(s) + 2CO(g) → V2O3(s) + 2CO2(g); ΔH° = –234.2 kJ; ΔS° = 0.2 J/K calculate ΔG° for the following at 298 K: 2V(s) + 5CO2(g) → V2O5(s) + 5CO(g

Answers

Answer:

ΔG° = -133,1 kJ

Explanation:

For the reactions:

(1) V₂O₃(s) + 3CO(g) → 2V(s) + 3CO₂(g); ΔH° = 369,8 kJ; ΔS° = 8,3 J/K

(2) V₂O₅(s) + 2CO(g) → V₂O₃(s) + 2CO₂(g); ΔH° = –234,2 kJ; ΔS° = 0,2 J/K

By Hess's law it is possible to obtain the ΔH° and ΔS° of:

2V(s) + 5CO₂(g) → V₂O₅(s) + 5CO(g)

Substracting -(1)-(2), that means:

ΔH° = -369,8 kJ - (-234,2 kJ) = -135,6 kJ

ΔS° = - 8,3 J/K - 0,2 J/K = -8,5 J/K

Using: ΔG° = ΔH° - TΔS° at 298K

ΔG° = -135,6 kJ - 298K×-8,5x10⁻³kJ/K

ΔG° = -133,1 kJ

I hope it helps!

Final answer:

To calculate the standard Gibbs free energy change (ΔG°) for the desired reaction at 298 K, reverse the first reaction, multiply the second by 2, sum their ΔH° and ΔS° values, and use the Gibbs free energy equation.

Explanation:

To calculate the standard Gibbs free energy change (ΔG°) for the reaction 2V(s) + 5CO2(g) → V2O5(s) + 5CO(g) at 298 K, we need to use the given information from two different reactions and apply Hess's law. First, we need to reverse the first reaction and multiply the second reaction by 2 to get the formation of V2O5(s) from V(s) and CO2(g). The ΔH° and ΔS° values of the first reaction would become -369.8 kJ and -8.3 J/K, respectively, after being reversed. For the second reaction, these values are -468.4 kJ and 0.4 J/K after being multiplied by 2. Adding these values provides the ΔH° and ΔS° for the overall reaction.

The ΔH° and ΔS° are then used to calculate ΔG° using the Gibbs free energy equation: ΔG° = ΔH° - TΔS°. Substituting the values, we find ΔG° for the overall reaction. This will tell us whether the reaction is spontaneous at 298 K, with a negative ΔG° indicating a spontaneous process.

From each of the following pairs of substances, use data in Appendix E in the textbook to choose the one that is the stronger oxidizing agent.Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.1. Given HO2- (aq) or O3 (g), the stronger oxidizing agent is _____.2. Given Cl2 (g) or I2 (s), the stronger oxidizing agent is _____.3. Given Zn^2+ (aq) or Co^2+ (aq), the stronger oxidizing agent is _____.4. Given Br2 (l) or BrO3- (aq), the stronger oxidizing agent is _____.WORD BOX:Zn^2+ (aq)O3 (g)I2 (s)HO2- (aq)Cl2 (g)Br2 (l)Co^2+ (aq)BrO3- (aq)

Answers

Final answer:

To determine the stronger oxidizing agent in each pair of substances, compare the oxidizing strengths using data from Appendix E. The stronger oxidizing agents are O3(g), Cl2(g), Co2+(aq), and BrO3-(aq).

Explanation:

To determine the stronger oxidizing agent in each pair, we need to compare the oxidizing strengths of the substances. From Appendix E in the textbook, we can find the relevant data. Here are the answers:

Given HO2- (aq) or O3 (g), the stronger oxidizing agent is O3 (g).Given Cl2 (g) or I2 (s), the stronger oxidizing agent is Cl2 (g).Given Zn2+ (aq) or Co2+ (aq), the stronger oxidizing agent is Co2+ (aq).Given Br2 (l) or BrO3- (aq), the stronger oxidizing agent is BrO3- (aq).

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Final answer:

To determine the stronger oxidizing agent, compare the standard reduction potentials of the species in each pair. The substance with the higher standard reduction potential is the stronger oxidizing agent.

Explanation:

To determine the stronger oxidizing agent in each pair, we need to compare their standard reduction potentials. The substance with the higher standard reduction potential is the stronger oxidizing agent. From Appendix E, we can find the standard reduction potentials of the species in each pair and compare them to determine the stronger oxidizing agent.

Given HO2- (aq) or O3 (g), the stronger oxidizing agent is O3 (g).Given Cl2 (g) or I2 (s), the stronger oxidizing agent is Cl2 (g).Given Zn2+ (aq) or Co2+ (aq), the stronger oxidizing agent is Co2+ (aq).Given Br2 (l) or BrO3- (aq), the stronger oxidizing agent is BrO3- (aq).

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Which of the statements about enzymes are true?
a. Nonbiological catalysts and enzymes tend to have a similar degree of reaction specificity.
b. Catalysis occurs at the active site, which usually consists of a crevice on the surface of the enzyme.
c. Generally, an enzyme is specific for a particular substrate. For example, thrombin catalyzes the hydrolysis of the peptide bond between Arg and Gly.

Answers

Answer: b. Catalysis occurs at the active site, which usually consists of a crevice on the surface of the enzyme.

c. Generally, an enzyme is specific for a particular substrate. For example, thrombin catalyzes the hydrolysis of the peptide bond between Arg and Gly.

Explanation:

The role of the enzyme is to produce a specific product, whereas the non-biological catalyst produces more than one product. Thus they have a different degree of reaction specificity.

The active site of the enzyme is the catalytic site of the enzyme. It is the region where the substrate molecule bind and undergoes a chemical reaction. The enzyme exhibit a special crevice or opening at the active site which facilitates the binding with the substrate.

Enzymes usually bind to a specific substrate as they have an active site that allows a particular substrate to bind to the active site of the enzyme. This is because of the shape of the active site of the enzyme which has a binding affinity with a particular substrate any other substrate cannot bind to the active site.

What is the pH of a 0.0042 M hydrochloric acid solution?
A) 5.47
B) 11.62
C) 7.00
D) 8.53
E) 2.38

Answers

Answer:

E) 2.38

Explanation:

The pH of any solution , helps to determine the acidic strength of the solution ,

i.e. ,

Lower the value of pH , higher is its acidic strength

and ,

Higher the value of pH , lower is its acidic strength .

pH is given as the negative log of the concentration of H⁺ ions ,

hence ,

pH = - log H⁺

From the question ,

the concentration of the solution is 0.0042 M , and being it a strong acid , dissociates completely to its respective ions ,

Therefore , the concentration of H⁺ = 0.0042 M .

Hence , using the above equation , the value of pH can be calculated as follows -

pH = - log H⁺

pH = - log ( 0.0042 M )

pH =  2.38 .

Final answer:

HCl is a strong acid, and its dissociation yields an equal concentration of hydrogen ions. Thus, the correct options is E) 2.38.

Explanation:

The pH of a 0.0042 M hydrochloric acid solution can be calculated using the formula [tex]pH = -log[H+][/tex], where [tex][H+][/tex] is the concentration of hydrogen ions.

In a solution of hydrochloric acid, which is a strong acid, the concentration of hydrogen ions [tex][H+][/tex] is equal to the concentration of the acid itself because [tex]HCl[/tex]dissociates completely in water.

Thus, the pH of the 0.0042 [tex]M HCl[/tex] solution is calculated as follows:

[tex]pH = -log(0.0042)[/tex]

= 2.38.

Therefore, the correct answer is E) 2.38.

For the reaction shown here

8H2S(g) ---> <--- 8H2(g) + S8(g)

the equlibrium concentrations were found to be

[H2S] = 0.250 M
[H2] = 0.400 M
[S8] = 0.750 M

What is the equilibrium constant for this reaction?

Kc = ???

Answers

The equilibrium constant for the reaction is 32.2

The equilibrium constant (K꜀) for a given reaction is simply defined as the ratio of the concentration of the products raised to their coefficients to the concentration of the reactants raised to their coefficients

With the above information, we can obtain the equilibrium constant for the reaction given above as follow:

8H₂S(g) <=> 8H₂(g) + S₈(g)

Concentration of Hydrogen sulphide [H₂S] = 0.250 M

Concentration of Hydrogen [H₂] = 0.400 M

Concentration of sulphur [S₈] = 0.750 M

Equilibrium constant (K꜀) =?

[tex]K_{C} = \frac{[H_{2}]^8[S_{8}]}{[H_{2}S]^{8}} \\\\K_{C} = \frac{0.4^{8} * 0.750}{0.25^{8}}\\\\[/tex]

K꜀ = 32.2

Therefore, the equilibrium constant for the reaction is 32.2

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Final answer:

The equilibrium constant Kc for the given reaction is determined from the ratio of the product concentrations to the reactant concentrations, each raised to the power of their stoichiometric coefficients.

Explanation:

The equilibrium constant Kc for a chemical reaction is calculated from the concentrations of the products divided by the concentrations of the reactants, each raised to the power of their stoichiometric coefficients.

Given the reaction equation: 8H2S(g) 8H2(g) + S8(g)

And the equilibrium concentrations: [H2S] = 0.250 M, [H2] = 0.400 M, [S8] = 0.750 M

The equilibrium constant Kc is therefore: Kc = ([H2]^8 * [S8]) / ([H2S]^8) = (0.400^8 * 0.750) / (0.250^8).

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A sample containing 2.50 mol of an ideal gas at 298 K is expanded from an initial volume of 10.0 L to a final volume of 50.0 L. Calculate ΔG and ΔA for this process for:
(a) an isothermal reversible path and (b) an isothermal expansion against a constant external pressure of 0.750 bar. Explain why ΔG and ΔA do or do not differ from one another.

Answers

Final answer:

In an isothermal reversible expansion, ΔG and ΔA do not differ and can be calculated using the natural log of the ratio of final to initial volumes. During an isothermal expansion against a constant external pressure, while ΔG can vary due to the external work being done, ΔA remains more reflective of internal work under constant conditions.

Explanation:

The question asks for the calculation of ΔG (Gibbs Free Energy change) and ΔA (Helmholtz Free Energy change) for the isothermal expansion of an ideal gas under two scenarios: (a) a reversible path and (b) an expansion against a constant external pressure. Both ΔG and ΔA can be insightful in understanding the spontaneity and energy changes of a chemical process.

(a) Isothermal Reversible Expansion

For an isothermal reversible expansion, ΔG and ΔA do not differ because both depend on the same variables in an ideal condition. Since the temperature is constant and the process is reversible, the free energy changes can be calculated using the formulas:

ΔG = -nRT ln(Vf/Vi) ΔA = -nRT ln(Vf/Vi)

Given: n = 2.50 mol, T = 298 K, Vi = 10.0 L, and Vf = 50.0 L

This leads to the same value for both ΔG and ΔA, showing that the only driving force behind the reversible isothermal expansion is entropy.

(b) Isothermal Expansion Against a Constant External Pressure

When expanding against a constant external pressure of 0.750 bar, the pressure-volume work becomes different. However, ΔG can still be calculated using the formula for isothermal processes in the presence of external pressure, but would yield a different context compared to ΔA which is not typically affected by external pressure in the same straightforward manner.

ΔG is defined by the system's ability to do non-PV work, and in isothermal conditions against constant external pressures, its calculation might deviate, illustrating differences in real-world versus ideal conditions. ΔA would not generally change because it pertains to the work done in a closed system at constant temperature and volume.

A 1.40 L sample of O2 at 645 Torr and 25 °C, and a 0.751 L sample of N2 at 1.13 atm and 25 °C, are both transferred to the same 2.00 L container at 25 °C. What are the partial pressures of the two gases and the total pressure inside the 2.00 L container? Show your work.

Answers

Answer:

P(O₂) = 0.595 atmP(N₂) = 0.424 atmTotal Pressure = 1.019 atm

Explanation:

To solve this problem we use PV=nRT for both gases in their containers, in order to calculate the moles of each one:

O₂:

645 Torr ⇒ 645 /760 = 0.85 atm

25°C ⇒ 25 + 273.16 = 298.16 K

0.85 atm * 1.40 L = n * 0.082 atm·L·mol⁻¹·K⁻¹ *298.16 K

n = 0.0487 mol O₂

N₂:

1.13 atm * 0.751 L = n * 0.082 atm·L·mol⁻¹·K⁻¹ *298.16 K

n = 0.0347 mol N₂

Now we can calculate the partial pressure for each gas in the new container, because the number of moles did not change:

O₂:

P(O₂) * 2.00 L = 0.0487 mol O₂ * 0.082 atm·L·mol⁻¹·K⁻¹ *298.16 K

P(O₂) = 0.595 atm

N₂:

P(N₂) * 2.00 L = 0.0347 mol N₂ * 0.082 atm·L·mol⁻¹·K⁻¹ *298.16 K

P(N₂) = 0.424 atm

Finally we add the partial pressures of all gases to calculate the total pressure:

Pt = 0.595 atm+ 0.424 atm = 1.019 atm

Final answer:

To find the partial pressures and total pressure in the container, convert pressures to atm, apply the ideal gas law for each gas, and sum the resulting partial pressures. The partial pressures are 0.5959 atm for O₂ and 0.4249 atm for N₂, with a total pressure of 1.0208 atm.

Explanation:

The question asks to calculate the partial pressures of O₂ and N₂ as well as the total pressure in a 2.00 L container at 25 °C, after transferring 1.40 L of O₂ at 645 Torr and 0.751 L of N₂ at 1.13 atm into it. To solve this, the pressure values need to be converted to a common unit (atmospheres), and the ideal gas law used for calculations.

First, convert the O₂ pressure from Torr to atm: 645 Torr / 760 = 0.8487 atm. Then use the ideal gas law (P₁V₁ = P₂V₂) to find the new pressures in the 2.00 L container. For O₂, (0.8487 atm)(1.40 L) / 2.00 L = 0.5959 atm. The pressure of N₂ is already in atm, so, (1.13 atm)(0.751 L) / 2.00 L = 0.4249 atm.

The total pressure is the sum of the partial pressures: 0.5959 atm (O₂) + 0.4249 atm (N₂) = 1.0208 atm. Therefore, the partial pressures are 0.5959 atm for O₂ and 0.4249 atm for N₂, with a total pressure of 1.0208 atm in the container.

Calculate the number of milliliters of 0.587 M NaOH required to precipitate all of the Ni2+ ions in 163 mL of 0.445 M NiBr2 solution as Ni(OH)2. The equation for the reaction is: NiBr2(aq) + 2NaOH(aq) Ni(OH)2(s) + 2NaBr(aq) mL NaOH Submit AnswerRetry Entire Group

Answers

Answer:

We need 247 mL of NaOH

Explanation:

Step 1: Data given

Molarity of NaOH = 0.587 M

Volume of 0.445 M NiBr2 solution = 163 mL = 0.163 L

Step 2: The balanced equation

NiBr2(aq) + 2NaOH(aq) Ni(OH)2(s) + 2NaBr(aq)

Step 3: Calculate moles of NiBr2

Moles NiBR2 = Molarity NiBR2 * volume

Moles NiBR2 = 0.445 M * 0.163 L

Moles NiBR2 = 0.0725 moles

Step 3: Calculate moles of NaOH

For 1 mol NiBr2 consumed, we need 2 moles NaOH

For 0.0725 moles NiBR2, we need 2* 0.0725 = 0.145 moles NaOH

Step 4: Calculate volume of NaOH

Volume = moles NaOH / Molarity NaOH

Volume = 0.145 moles / 0.587 M

volume = 0.247L = 247 mL

We need 247 mL of NaOH

Be sure to answer all parts. The net change in the multistep biochemical process of photosynthesis is that CO2 and H2O form glucose (C6H12O6) and O2. Chlorophyll absorbs light in the 600 to 700 nm region. What is the minimum number of photons with 680. nm needed to prepare 1.00 mol of glucose? Assume CO2 to be a gas and glucose to be a solid.

Answers

Answer:

9.86 × 10²⁴ photons

Explanation:

Let's consider the photosynthesis global reaction.

6 CO₂(g) + 6 H₂O(l) →  C₆H₁₂O₆(s) +  6 O₂(g)

We can calculate the standard Gibbs free energy of the reaction (ΔG°) using the following expression.

ΔG° = ∑np . ΔG°f(p) - ∑nr . ΔG°f(r)

where,

ni are the moles of reactants and products

ΔG°f(p) are the standard free Gibbs energies of formation of reactants and products

For the balanced equation for 1.00 mol of glucose, ΔG° is:

ΔG° = [1 mol × ΔG°f(C₆H₁₂O₆(s)) + 6 mol × ΔG°f(O₂(g))] - [6 mol × ΔG°f(CO₂(g)) + 6 mol × ΔG°f(H₂O(l))]

ΔG° = [1 mol × (-910.6 kJ/mol) + 6 mol × 0 kJ/mol] - [6 mol × (-394.4 kJ/mol) + 6 mol × (-237.1 kJ/mol)]

ΔG° = 2878 kJ

The energy of each photon (E) can be calculated using the Planck-Einstein's equation.

E = h . c. λ⁻¹

where,

h is the Planck's constant

c is the speed of light

λ is the wavelength

E = (6.626 × 10⁻³⁴ J.s) × (3.00 × 10⁸ m/s) × (680 × 10⁻⁹ m)⁻¹ = 2.92 × 10⁻¹⁹ J

The minimum number of photons required is:

[tex]2878\times 10^{3} J.\frac{1photon}{2.92\times 10^{-19}J} =9.86 \times 10^{24}photon[/tex]

Final answer:

The net change in photosynthesis involves forming glucose and O2 from CO2 and H2O with the aid of solar energy. The minimum number of photons needed at 680 nm to form 1.00 mol of glucose can be calculated using the energy requirements for the synthesis of glucose in photosynthesis.

Explanation:

The question pertains to the light-dependent reactions of photosynthesis, where solar energy is absorbed by chlorophyll to produce glucose from CO2 and H2O. Calculating the minimum number of photons with a wavelength of 680 nm needed to prepare 1.00 mol of glucose requires understanding the energy associated with photons and the process of photosynthesis. Since solar energy is converted into chemical energy in the form of ATP and NADPH during photosynthesis, and a total of 54 ATP equivalents are required to synthesize one molecule of glucose, the number of photons must provide at least this much energy. Considering that each photon's energy is inversely proportional to its wavelength, we can use the relationship E = hc/λ (where E is energy, h is Planck's constant, c is the speed of light, and λ is wavelength) to calculate the energy of a photon of 680 nm, and subsequently, determine the total number of photons required to provide the 54 ATP equivalents needed for glucose synthesis.

The rate law of a certain reaction is rate=k[X][Y]. The units of k, with measured in seconds, is
A.) s^-1
B.) M^-1 s^-1
C.) M^-2 s^-1
D.) M^-1

Answers

Answer:

The correct option is: B.) M^-1 s^-1

Explanation:

According to the rate law, the rate of a given chemical reaction is equal to the product of the reactant concentrations. Where, the exponents a and b are the partial orders for the concentration of X and Y, respectively.

The rate equation for the chemical reaction is:

Rate = k [X]ᵃ[Y]ᵇ

Here, k is the rate constant.

The concentration of X and Y reactants is given in mol.L⁻¹ or M (molarity).

The unit of rate of a chemical reaction is mol.L⁻¹.s⁻¹ or molarity per second M.s⁻¹

Given: rate = k [X][Y]              

In the given rate equation, the exponents of concentrations of reactants X and Y is 1. Thus the overall order of the reaction is 2.

Therefore, it is a second order reaction.

Since the unit of rate is M.s⁻¹ and units of [X] and [Y] is M.

∴ [tex]Rate (M.s^{-1}) = k [X (M)] [Y (M)][/tex]

⇒ [tex]k = \frac{Rate (M.s^{-1})}{[X (M)] [Y (M)]} [/tex]

the unit of k in the given rate law equation = M⁻¹.s⁻¹

Final answer:

The units of k in the rate law equation rate=k[X][Y] are M^-1 s^-1, which correspond to a second-order reaction. These units arise because the rate constant unit must counteract the reactant concentrations unit, providing the reaction rate (usually M s^-1).

Explanation:

The given reaction rate law is rate=k[X][Y] where k is the rate constant, and [X] and [Y] are the molar concentrations of substances X and Y. The units of k, the rate constant, are determined by the reaction's overall order, which, in this case, is a sum total of the individual reaction orders of X and Y. In this scenario, the reaction is second-order (one for [X] and one for [Y]). Therefore, the units of k would be M-1 s-1 (Molarity inverse second inverse) as given by option B. It is inferred as M-1 s-1 because the rate constant unit must cancel out the units of the reactant concentrations to give the rate of the reaction (which is typically in M s-1).

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The manufacturer specs for a particular balloon indicate the maximum inflated volume is 3.00 L. The balloon is filled with 2.50 L of helium at sea level (assume P= 1.00 atm) and released. When the balloon rises to a higher altitude where the pressure is 450.0 mm Hg, will the balloon burst? Show a calculation to support your answer. Assume constant temperature.

Answers

Answer: The balloon will burst as it occupies higher volume than  maximum inflated volume.

Explanation:

To calculate the new volume, we use the equation given by Boyle's law. This law states that pressure is inversely proportional to the volume of the gas at constant temperature.  

The equation given by this law is:

[tex]P_1V_1=P_2V_2[/tex]

where,

[tex]P_1[/tex] = initial pressure of gas= 1.00 atm = 760.0 mm Hg  

[tex]V_1[/tex] =  initial volume of gas = 2.50 L

[tex]P_2[/tex] = final pressure of gas= 450.0 mm Hg

[tex]V_2[/tex] = final volume of gas = ?

Putting values in above equation, we get:

[tex]760.0\times 2.50=450.0\times V_2[/tex]

[tex]V_2=4.22L[/tex]

Thus the final volume of the gas is 4.22 L and as the maximum inflated volume is 3.00 L, the balloon will burst.

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