The silver nitrate in 20.00 mL of a certain solution was allowed to react with sodium chloride according to the following equation AgNO3 + NaCl yields AgCl + NaNO3 They AgCl was collected, dried and weighed to .2867g AgCl What was the molarity of the original silver nitrate solution?

Answer:

d

Explanation:

The mastodon was estimated to have died around 13,752 years ago, as deduced using Carbon-14 dating. This period corresponds to when early North American humans likely hunted large games, including woolly mammoths using group cooperation and advanced tools.

Understanding the life and death of a mastodon involves knowing the process of Carbon-14 dating and using this method to estimate the time-frame of the mastodon's demise. Carbon-14 undergoes radioactive decay and has a half-life of approximately 5730 years. In this problem, it is stated that 2.4 half-lives have passed since the mastodon was killed. Therefore, by multiplying the half-life of Carbon-14 (5730 years) by the number of half-lives that have passed (2.4), we can estimate that the mastodon died around 13,752 years ago.

This timescale fits into the period when early North American humans were known to have hunted large game, such as the woolly mammoths. Both archaeological evidence and cave paintings suggest coordinated hunting efforts with the use of sophisticated tools. The simultaneous occurrence of human migration, climate changes, and habitat reduction has been detected in this time frame, adding to the plausibility of human hunting leading to the extinction of these large animals.

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Answer: a) The substance is a silvery white, lustrous metal :physical property.  

b) It melts at 649°C and boils at 1105°C : physical property.  

c) Its density at 20°C is [tex]1.738 g/cm^3[/tex]: physical property.  

d)  The substance burns in air, producing an intense white light : chemical property

Explanation:

Chemical property is defined as the property of a substance which is observed during a reaction where the chemical composition identity of the substance gets changed.

Physical property is defined as the property which can be measured and whose value describes the state of physical system. For Example: State, density etc.

a) The substance is a silvery white, lustrous metal is a physical property

b) It melts at 649°C and boils at 1105°C is a physical property.  

c) Its density at 20°C is [tex]1.738 g/cm^3[/tex] is a physical property.  

d) The substance burns in air, producing an intense white light is a chemical property

Final answer:

Observations (a), (b), and (c) regarding the metal's appearance, melting and boiling points, and density are physical properties. Observation (d) describes a chemical property, as it involves the substance's ability to burn in air.

Explanation:

In the process of characterizing a substance, a chemist observes certain properties which can be classified as either physical properties or chemical properties.

Answer:

A rag contaminated with gasoline is considered a hazard waste. The question seems to be asked to ask for indications of rag disposal on a ship, and if so, the answer is d) Discard it on land BUT with special precautions

Explanation:

Gasoline is a highly flammable organic solvent that is used as fuel. For the above is a dangerous substance. while the ship reaches the mainland, the rag must be stored avoiding contact with environmental agents such as the sun, pets or food. Once in a dry land the rag can be delivery for accurate disposal.

I hope my answer helps you

Final answer:

Monosodium glutamate is a compound made up of sodium, carbons, hydrogen, nitrogen, and oxygen.

Explanation:

Monosodium glutamate is a compound.

It is the sodium salt of glutamic acid, a naturally occurring non-essential amino acid.

Compounds are substances made up of two or more elements that are chemically bonded together.

In this case, monosodium glutamate is made up of the elements sodium (Na), carbon (C), hydrogen (H), nitrogen (N), and oxygen (O).

Answer:

The answer to your question is: letter D 10 l

Explanation:

Data

V1 = 5.8 l

P1= 760 mmHg

T 0 constant

P2 = 430 mmHg

V2 = ?

Formula

V1P1 = V2P2

and we clear V2 from the equation

V2 = V1P1/P2

V2 = (5.8)(760)/430)

V2 = 10.25 l

According to the Boyle's law, the final volume of the gas which is expanded till the pressure of 430 mm Hg  is 10.25 L.

Boyle's law is an experimental gas law which describes  how the pressure of the gas decreases as  the volume increases. It's  statement can be stated as, the absolute pressure which is exerted by a given mass of an ideal gas is inversely proportional to its volume provided temperature and amount of gas remains unchanged.

Mathematically, it can be stated as,

P∝1/V or PV=K. The equation states that the product of of pressure and volume is constant for a given mass of gas and the equation holds true as long as temperature is maintained constant.

According to the equation the unknown pressure and volume of any one gas can be determined if two gases are to be considered.That is,

P₁V₁=P₂V₂

∴V₂=5.8×760/430=10.25 L.

Therefore, the final volume of the gas is 10.25 L.

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Final answer:

The correct equation for the reaction between two molecules of sodium hydroxide and one molecule of sulfuric acid is 2NaOH+H2SO4→Na2SO4+2H2O.

Explanation:

The equation that correctly describes the reaction where two molecules of sodium hydroxide react with one molecule of sulfuric acid to form one molecule of sodium sulfate and two molecules of water is: 2NaOH+H2SO4→Na2SO4+2H2O. This equation illustrates a neutralization reaction whereby sulfuric acid (a strong acid) reacts with sodium hydroxide (a strong base) to produce sodium sulfate, a salt, along with water. This is an example of a reaction with a diacid, where two moles of the base are required to fully neutralize one mole of the diacid, resulting in a salt and water as the products.

Answer:

Cl2(g) (green/yellow mix) + 2KBr(s) (white) ---> 2KCl(s) (violet) + Br2(g) (reddish brown)

This chemical reaction is a redox type.

Explanation:

Look at the oxidation state, when the number increase your element gets oxidated, when the number decrease, the elements it's getting reduced.

Answer:  The molar mass of the unknown gas is 59.8 g/mol

Explanation:

According to the ideal gas equation:-

[tex]PV=nRT[/tex]

P= Pressure of the gas = 706 mmHg = 0.93 atm    (760mmHg=1atm)

V= Volume of the gas = 1.64 L

T= Temperature of the gas = 59°C=(59+273)K=332 K   (0°C = 273 K)

R= Value of gas constant = 0.0821 Latm\K mol

[tex]n=\frac{PV}{RT}=\frac{0.93\times 1.64L}{0.0821 \times 332}=0.056moles[/tex]

To calculate the moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}[/tex]

[tex]0.056=\frac{3.35g}{\text {Molar mass}}[/tex]

[tex]{\text {Molar mass}}=59.8g[/tex]

Thus the molar mass of the unknown gas is 59.8 g/mol

The molar mass of the unknown gas is calculated using the ideal gas law equation. After converting the pressure to atmospheres and temperature to Kelvin, the molar mass is found to be 57.46 g/mol.

To calculate the molar mass of the unknown gas, we will use the ideal gas law equation PV = nRT, where P is pressure, V is volume, n is the amount of moles, R is the ideal gas constant, and T is temperature in Kelvin. We can rearrange the formula to solve for n (moles) and then use the mass of the gas to find its molar mass.

First, let's convert the given pressure and temperature to standard units. Pressure in atmospheres (atm) is 706 mmHg × (1 atm / 760 mmHg) = 0.9295 atm. Temperature in Kelvin (K) is 59 °C + 273 = 332 K.

Now we can use the ideal gas law equation:

PV = nRT

0.9295 atm × 1.64 L = n × 0.0821 L·atm·K¹·mol¹ × 332 K

Solving for n (moles), we get n = 0.0583 mol.

The molar mass (MM) is the mass of the gas divided by the number of moles:

Molar Mass = Mass / Moles

Molar Mass = 3.35 g / 0.0583 mol = 57.46 g/mol

approximately [tex]\( 6.22 \times 10^5 \% \)[/tex] of the total red blood cell volume is taken up by [tex]\( \text{Fe}^{2+} \)[/tex] ions.

To find the percentage of the total red blood cell volume taken up by [tex]\( \text{Fe}^{2+} \)[/tex] ions, we first need to calculate the volume occupied by [tex]\( \text{Fe}^{2+} \)[/tex] ions and then express it as a percentage of the total volume of the red blood cell.

1. Calculate the Volume Occupied by [tex]\( \text{Fe}^{2+} \)[/tex] Ions:

  The volume occupied by [tex]\( \text{Fe}^{2+} \)[/tex] ions can be calculated based on the number of ions and their atomic radius.

  Each [tex]\( \text{Fe}^{2+} \)[/tex] ion can be considered as a sphere, and its volume [tex](\( V_{\text{Fe}^{2+}} \))[/tex] can be calculated using the formula for the volume of a sphere:

  [tex]\[ V_{\text{Fe}^{2+}} = \frac{4}{3} \pi r^3 \][/tex]

  where r is the atomic radius of [tex]\( \text{Fe}^{2+} \)[/tex] ions.

  Given that the atomic radius of [tex]\( \text{Fe}^{2+} \)[/tex] ions is [tex]\( 75.1 \, \text{pm} \)[/tex] [tex](or \( 75.1 \times 10^{-12} \, \text{m} \))[/tex], we can calculate the volume of one [tex]\( \text{Fe}^{2+} \)[/tex] ion.

  Then, multiply this volume by the number of [tex]\( \text{Fe}^{2+} \)[/tex] ions present in a single red blood cell to find the total volume occupied by [tex]\( \text{Fe}^{2+} \)[/tex] ions.

2. Calculate the Percentage of the Total Red Blood Cell Volume:

  After obtaining the volume occupied by [tex]\( \text{Fe}^{2+} \)[/tex] ions, divide it by the total volume of the red blood cell and multiply by 100 to express it as a percentage.

Let's perform the calculations:

1. Calculate the Volume Occupied by [tex]\( \text{Fe}^{2+} \)[/tex] Ions:

  [tex]\[ V_{\text{Fe}^{2+}} = \frac{4}{3} \pi (75.1 \times 10^{-12} \, \text{m})^3 \][/tex]

  [tex]\[ V_{\text{Fe}^{2+}} = \frac{4}{3} \pi (4.468 \times 10^{-10} \, \text{m}^3) \][/tex]

  [tex]\[ V_{\text{Fe}^{2+}} = 2.363 \times 10^{-9} \, \text{m}^3 \][/tex]

  Now, we need to find the total volume occupied by [tex]\( \text{Fe}^{2+} \)[/tex] ions in the red blood cell:

  [tex]\[ V_{\text{total Fe}^{2+}} = (2.50 \times 10^8 \, \text{molecules}) \times (2.363 \times 10^{-9} \, \text{m}^3/\text{ion}) \][/tex]

  [tex]\[ V_{\text{total Fe}^{2+}} = 5.908 \times 10^{-1} \, \text{m}^3 \][/tex]

2. **Calculate the Percentage of the Total Red Blood Cell Volume:**

  Given that the volume of the red blood cell is [tex]\( 95 \, \mu\text{m}^3 \) (or \( 95 \times 10^{-18} \, \text{m}^3 \))[/tex], we can calculate the percentage:

  [tex]\[ \text{Percentage} = \frac{V_{\text{total Fe}^{2+}}}{V_{\text{RBC}}} \times 100 \][/tex]

  [tex]\[ \text{Percentage} = \frac{5.908 \times 10^{-1} \, \text{m}^3}{95 \times 10^{-18} \, \text{m}^3} \times 100 \][/tex]

  [tex]\[ \text{Percentage} \approx 6.22 \times 10^5 \% \][/tex]

Therefore, approximately [tex]\( 6.22 \times 10^5 \% \)[/tex] of the total red blood cell volume is taken up by [tex]\( \text{Fe}^{2+} \)[/tex] ions.

Answer:

The answer to your question is: neutrons

Explanation:

None of the components have charges. This is incorrect because the atoms is composed by three particles, neutrons, electrons and protons, and the characteristic of an atom is that its particles at least some are charged.

neutrons: are particles located in the nucleus and they diminish the repulsion forces among the protons. They don't have any charge

electrons : they are located in the shells are are negative charged.

protons: they are located in the nucleus and are positive charged.

Answer:

neutrons

Explanation:

Answer:

The molarity of the sulfuric acid is 0.018 M

Explanation:

The molarity of a solution is the number of moles of the solute (sulfuric acid in this case) in a 1-liter solution.

Every 100 g of the solution, we have 95 g sulfuric acid because its concentration is 95% w/w.

With the density, we can calculate how many liters are 100 g of solution:

density = mass / volume

1.85 g / ml = 100 g / volume

volume = 100 g / 1.85 g/ml

volume = 54.1 ml or 0.0541 l

Now, we know that we have 95 g sulfuric acid in 0.0541 l solution. In 1 l, we have then:

1 l * 95g / 0.0541 l = 1.756 g sulfuric acid.

But we want to know how many moles sulfuric acid we have per liter. Then, using the molar mass, we can calculate how many moles there are in 1.756 g sulfuric acid:

1.756 g * 1 mol / 98.08 g = 0.018 mol

The molarity is 0.018 M

Answer:

Robert

Explanation:

Paper chromatography is an analytical technique which is used to separate different components dissolved in a mixture depending on the time taken by each component to travel up the paper. The difference in time depends on the relative affinity of a particular component towards the paper (which acts as the stationary phase) and the solution carrying the mixture (which acts as the mobile phase).

This method is commonly used to separate colored systems like a dye mixture. The presence of more than one dye in a mixture shows up as a band of a color characteristic of that component.

Jim, Jill and Kim each have two bands in their paper chromatogram which suggests that they have two substances in their mixture. However, Robert has a single green band which indicates the presence of only one substance dissolved in water.

Answer:

a. The reaction associated with DHºf for an ionic compound

Explanation:

An exothermic process is a process that loses heat for the surroundings, so the temperature of the system must decrease, and ΔH must be negative.

DHºf or ΔHºf of an ionic compound is always negative because the final energy is always lower than the initial. It happens because of the stability of the bond, the system wants a lower energy state to be stable.

The ionization of a lithium atom occurs with the gain of energy, which is given to the electron, so it may give off the atom. So it's an endothermic process.

To change the state of a solid to a gas (sublimation), the compound must gain heat, its temperature must increase, so it's always an endothermic process.

To break a covalent bond it's necessary the gain of energy, so it's an endothermic process.

Answer:A

Explanation:

The enthalpy change of formation for an ionic compound is calculated from the Born-Haber cycle. Using the Hess law of constant heat summation. The result is always negative (exothermic) because energy is given out when the new lattice is formed.

Answer:

See below.

Explanation:

Argon gas is a pure substance. It has nothing other than molecules of Argon gas.

Iron oxide is a compound with iron and oxygen as its components. It is a pure substance.

Answer:

c. The frequency of collisions between particles, the size of the particles.

Explanation:

The reaction among 2 substances could speed up if the size of particles is smaller, for example it is easier to dissolve the common sugar than a cube of sugar, the reason is because since the size is smaller, the total area that is exposed to react is bigger.

Also, the frequency of collisions between particles, can increase the rate of reaction, because if they collide faster, the probability of react is bigger.

Answer:

c

Explanation:

Answer:

You should know that density is the relation between, mass and volume as it is described in this equation: d = m/v. As the mass doesn't change in each piece, you will see that volume is less than the original, that's why each piece is 1/3 the density of the original bar or, you can also see, that you have increase by 3, the density original.

Explanation:

Answer:

1.25 moles of Ba(NO3)2 will be formed.

Explanation:

Given data:

moles of AgNO3 = 2.50 mol

moles of Ba(NO3)2 = ?

Solution:

First of all we will write the balance chemical equation.

2AgNO3 + BaCl2 → Ba(NO3)2 + 2AgCl

Now we compare the moles of AgNO3 and  Ba(NO3)2.

   AgNO3   :    Ba(NO3)2

     2           :        1

     2.5        :        1/2 × 2.5 = 1.25 moles

so, 2.50 moles of AgNO3 will produce 1.25 moles of Ba(NO3)2.

Answer:

0.375 grams are needed to make 25 mL solution.

Explanation:

Mass of [tex]AgNO_3[/tex] cuprous nitrate required to make 1 l of solution = 15 g.

1 L = 1000 mL

Mass of [tex]AgNO_3[/tex] cuprous nitrate required to make 1000 mL of solution = 15 g

Mass of [tex]AgNO_3[/tex] cuprous nitrate required to make 1 mL of solution:

[tex]=\frac{15}{1000} g[/tex]

Mass of [tex]AgNO_3[/tex] cuprous nitrate required to make 25 mL of solution:

[tex]=\frac{15}{1000} \times 25 g=0.375 g[/tex]

0.375 grams are needed to make 25 mL solution.

Answer and Explanation:

When methanol (CH₃OH) dissolves in water, the following equilibrium takes place:

CH₃OH + H₂O ⇄ CH₃O⁻ + H₃O⁺

The dissociation constant is about 10⁻¹⁶ (very very small), so methanol practically does not dissociate in its ions in water, thus the solution does not conduct electricity (because there is a very small quantity of ions).

By other hand, acetic acid (CH₃COOH) dissociates in water as follows:

CH₃COOH + H₂O ⇄ CH₃COO⁻ + H₃O⁺

and its dissociation constant is about 10⁻⁵, which is not negligible. So, there is a considerable quantity of ions in solution and they can conduct electricity.

Methanol doesn't ionize in water and therefore forms a non-conductive solution, while acetic acid does ionize partially, making it a weak conductor and imparting an acidic character to the solution. Also, differences in solution behaviour are due to inherent properties of the respective molecules.

When methanol (CH3OH) is dissolved in water, it does not produce ions; hence it is a nonconducting solution. Methanol is a covalent compound and does not ionize in water. Hence, no ions are formed and it does not conduct electricity.

On the other hand, when acetic acid (CH3COOH) dissolves in water, its molecules ionize slightly, forming CH3CO2- ions and H3O+ ions. Because the number of ions is less than that created by strong electrolytes, it conducts electricity weakly and is a weak electrolyte.

Furthermore, the ionization of acetic acid also generates H3O+ ions, making the solution acidic. Additionally, acetic acid can form dimers, which are pairs of acetic acid molecules, under certain conditions, contributing to its acidic nature.

The differences in solution behavior are due to the properties of the molecules themselves - methanol is a simple alcohol and does not tend to ionize, while acetic acid is a carboxylic acid that has an acidic hydrogen which it can donate (although not as readily as a strong acid).

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Answer:

The answer to your question is letter D.

Explanation:

A. Has a fixed volume This is not the right answer, liquids and gases take the shape of the container in which they are.

B. Particles stay in a fixed position This answer is wrong, this characteristic is  of solids but not of liquids and gases.

C. No particle movement This characteristic is also of solids, in liquids and gases the particles can move.

D. Takes the shape of the container. This is the right answer, liquids and gases take the shape of the container.

Answer:

D :)

Explanation:

Answer:

The answer to your question is: +4

Explanation:

Oxidation number of carbon in Li₂CO₃

To know the oxidation number of Carbon, first find the oxidation number of Li and Oxygen.

Li is located in group IA in the periodic table, and all the elements that belong to this group have an oxidation number of +1.

O is located in group VIA in the periodic table, all the elements of this group have an oxidation number of -2.

Also, consider that the sum of the oxidation numbers in a neutral molecule equals zero.

Then

              Lithium = +1 x 2 = +2

              Oxygen = -2 x 3 = -6

            +2 + Carbon oxidation number - 6 = 0

             Carbon oxidation number = 6 -2

             Carbon oxidation number = 4

The oxidation number of carbon in lithium carbonate is +4.

Given:

The compound - lithium carbonate  

To find :

The oxidation number of carbon in the given compound.

Solution:

The formula of lithium carbonate = [tex]Li_2CO_3[/tex]

Let the oxidation number of carbon be x.

The oxidation number of lithium is = +1

The oxidation number of oxygen = -2

The overall charge on the compound's molecule = 0

[tex]2\times (+1)+x+3\times (-2)=0\\\\+2+x-6=0\\\\x=+6-2=+4[/tex]

The oxidation number of carbon in lithium carbonate is +4.

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Answer:

C11H25SO4

Explanation:

The total mass of the compound is 253.4 g, so, the mass of each element will be:

C: 52.14% of 253.4 = 0.5214x253.4 = 132.12 g

H: 9.946% of 253.4 = 0.09946x253.4 = 25.20 g

S: 12.66% of 253.4 = 0.1266x253.4 = 32.08 g

O: 25.26% of 253.4 = 0.2526x253.4 = 64.00 g

The molar mass are: C = 12 g/mol, H 1 g/mol, S = 32 g/mol, and O = 16 g/mol

So, to know how much moles will be, just divide the mass calculated above for the molar mass:

C: 132.12/12 = 11 moles

H: 25.20/ 1 = 25 moles

S: 32.08/32 = 1 mol

O: 64.00/16 = 4 moles

So the molecular formula is C11H25SO4

Answer:

ester

Explanation:

methyl ethanoate is also known as methyl acetate

Answer : The correct option is, (b) R-COO-R'

Explanation :

Methyl ethanoate is also known as acetic acid methyl ester or methyl acetate. It is a carboxylate ester.

The formula of methyl ethanoate is, [tex]CH_3COOCH_3[/tex]

As we know that there are many functional groups which are:

(1) R-OH : It belongs to an alcoholic functional group in which the the -OH group is directly attached to the alkyl group of carbon.

(2) R-O-R' : It belongs to an ether functional group in which the the oxygen is directly attached to the two alkyl group of carbon.

(3) R-CO-R' : It belongs to ketone functional group in which the the -CO group is directly attached to the two alkyl group of carbon.

(4) R-CHO : It belongs to an aldehyde functional group in which the the -CHO group is directly attached to the alkyl group of carbon.

(5) R-COOH : It belongs to carboxylic acid functional group in which the the -COOH group is directly attached to the alkyl group of carbon.

(6) R-COO-R' : It belongs to ester functional group in which the the -COO group is directly attached to the two alkyl group of carbon.

From this we conclude that, the functional group found in methyl ethanoate is, ester.

Hence, the correct option is, (b) R-COO-R'

Final answer:

The limiting reactant is iron, which allows a maximum of 10.0 g of [tex]Fe_3O_4[/tex] to form from the reaction of 10.0 g of Fe and [tex]H_2O[/tex] according to the stoichiometry of the balanced equation.

Explanation:

Firstly, find the limiting reactant in the reaction between iron (Fe) and water [tex](H_2O)[/tex] to form iron(II,III) oxide [tex](Fe_3O_4)[/tex] and hydrogen gas [tex](H_2)[/tex].

The balanced chemical equation is: [tex]3 Fe(s) + 4 H_2O(l) \rightarrow Fe_3O_4(s) + 4 H_2(g)[/tex].

To find the limiting reactant, we convert the masses of the reactants into moles:

Using the stoichiometric coefficients from the balanced equation, we determine the ratio to find the limiting reactant:

For iron:

[tex]0.179 moles Fe \times (\frac{1 mol Fe_3O_4}{3 mol Fe})[/tex] = 0.0597 moles [tex]Fe_3O_4[/tex]

For water:

[tex]0.555 moles H_2O \times(\frac{1 mol Fe3O4}{4 mol H2O})[/tex] = 0.1388 moles [tex]Fe_3O_4[/tex]

Iron is the limiting reactant because it produces fewer moles of product. Now, we calculate the mass of [tex]Fe_3O_4[/tex] formed using the molar mass:

[tex]0.0597 moles Fe_3O_4 \times (231.55 g/mol)[/tex] = 13.82 g of [tex]Fe_3O_4[/tex]

However, since we cannot have a mass of product greater than the mass of our limiting reactant, the error must be in the significant figures. Taking into account significant figures, we have:

10.0 g Fe limit our product to a maximum of 10.0 g, so the real yield of [tex]Fe_3O_4[/tex] will be 10.0 g.

Answer: Option (a) is the correct answer.

Explanation:

Atomic number is the sum of only total number of protons present in an element. Whereas mass number is the sum of total number of both protons and neutrons present in an element.

For example, given atom has mass number as 15 and its atomic number is 7.

Therefore, number of neutrons present in it will be calculated as follows.

                    Mass number = no. of protons + no. of neutrons

                         15 = 7 + no. of neutrons

                    no. of neutrons = 15 - 7

                                               = 8

Thus, we can conclude that the given atom contains 8 neutrons in the nucleus.

Answer:

A solid residue of limestone and some gypsum.

Explanation:

In step 2, some of the limestone and gypsum in the chalk dissolve in the water. When the mixture is filtered, the dissolved substances remain in the water. When the water is boiled off or evaporated, the solid substances remain behind.

To calculate the pKa of the second ionizable group in compound X, after NaOH addition that adjusted the pH to 6.72, one would typically use the Henderson-Hasselbalch equation within the buffering range. The exact pKa calculation requires detailed balance of species post-titration.

The student's question involves calculating the pKa of the second ionizable group in an unknown compound X. Given that 75 mL of 0.1 M NaOH was added to 100mL of a 0.1 M solution of X at pH 2.0, and the pH increased to 6.72, we approach this problem through a series of chemical equilibrium and titration calculations. The pKa of the second group indicates its acid dissociation constant, which is crucial for understanding the compound's behavior in solution.

To calculate the pKa of the second ionizable group, we need to consider the buffering region and the Henderson-Hasselbalch equation. Given that the pH after the addition of NaOH reached a point beyond the first pKa but before the second pKa, it suggests that the solution is acting as a buffer. The pKa of the buffering component can be determined when the pH is within one pKa unit range above or below its value. Since the question provides a range for the second pKa between 5 and 8, and a result of 6.72 falls within this range, we can estimate the second pKa by aligning it with the observed buffer pH, given the stoichiometric conversion of species in solution.

The calculations for finding the exact pKa would require detailed knowledge of the buffering system's dynamics and the concentration of species post-titration. Normally, the Henderson-Hasselbalch equation is used: pH = pKa + log([A−]/[HA]), where [A−] is the concentration of the conjugate base, and [HA] is the concentration of the acid. However, due to the complexity and variability of chemical systems, exact calculations exceed this response's scope.

Answer:

The answer is: D

Explanation:

A. They have the same number of electron energy shells.  Is false, all the elements are in different periods so, they have different number of lectron energy shells.

B. They are all Halogens.  No, is wrong, halogens are F, Cl ,Br

C. They have the same number of electrons.  is wrong, if they had the same number of electrons they must be they same element and they aren't the same.

D. They are all Noble gases. Yes, it's true they are noble gases, they are the first group in the periodic table from the right.

Answer:

D-They are all noble gases

Explanation:

They have the same valency

Answer:

a. A non-competitive inhibitor of acetylcholinesterase.

Explanation:

The enzyme acetylcholinesterase breaks the molecule of acetylcholine, so to maintain the levels of this substance higher in the brain, the medication must act directly in the enzyme.

An enzyme can be inactivated by higher temperatures, changes in pH and changes in the osmotic pressure, but these things would probably damage other enzymes in the brain. So, the medication must be an inhibitor of acetylcholinesterase. It would be selective and would stop the actions of the enzyme.

But, this inhibitor can't be competitive because if this happens, it would break the acetylcholine, and wouldn't solve the problem.

Answer:

The answer to your question is: 6.8 g of water

Explanation:

Data

2.6 moles of HCl

1.4 moles of Ca(OH)2

                           2HCl     +     Ca(OH)2    →        2H2O    +      CaCl2

MW                   2(36.5)               74                       36 g               111 g

                          73g                

                            1 mol of HCl ----------------  36.5 g

                           2.6 mol           --------------    x

                              x = (2.6 x 36.5) / 1   = 94.9 g

                           1 mol of Ca(OH)2 --------------   74 g

                         1.4 mol                  ---------------   x

                            x = (1.4 x 74) / 1  = 103.6 g

Grams of water

                        73 g of HCl ------------------   36g of H2O

                        94.9 g        -------------------    x

                     x = (94.9 x 36) / 73 = 46.8 g of water

The amount of water is theoretically produced for the following reaction given we have 2.6 moles of HCl and 1.4 moles of Ca(OH)₂ -  C) 46.8.

Given:

2HCl + Ca(OH)₂ -------------> CaCl₂ + 2H2O

in this reaction, 2 moles HCl reacts with 1 mole Ca(OH)₂

which means 2.6 moles of HCl reacts with 2.6 x = 1.3

but we have 1.4 moles Ca(OH)₂  it is the excess reagent

Solution:

HCl is a limiting reagent in this reaction as it allows producing the mole of water on the base of the number of moles it has,

=> 2 mole HCl - 2 moles of H₂O

Here, 2.6 moles of HCl would give 2.6 moles of H₂O only

=> convert moles to mass  

moles = mass / molar mass  

and,

mass = [tex]\frac{mass}{molar\ mass}[/tex]

mass = 2.6 x 18

= 46.8 g

Thus, the amount of water is theoretically produced for the following reaction given we have 2.6 moles of HCl and 1.4 moles of Ca(OH)₂ -  C) 46.8.

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https://brainly.com/question/14537325