Which statement about intermolecular forces is true?

Group of answer choices
A. Only occur in ionic bonds.
B. They have to be overcome to decompose a substance.
C. These forces hold atoms together in a molecule.
D. They are responsible for the physical properties of matter.

Explanation:

The Lewis structures can be seen in the Figure below.

The ideal bond angle for both H-C-H and F-C-F is 120° because the have a triangular geometry.

The H-C-H has 117.4° angles due to the repulsion caused by the electrons of the double bond and the electrons of the H-C bond. This repulsion brings closer the H and decreases the angle.

On the other hand, in the F-C-F the same phenomenom happens but given that the F have lone pairs of electrons the repulsion is bigger, the F get closer and the angle is smaller than the H-C-H.

Final answer:

The Lewis structure for tetrafluoroethylene (C2F4) shows each carbon atom double-bonded to the other and single-bonded to two fluorine atoms, with an sp2 hybridization. The ideal bond angles for sp2 hybridized carbon are 120 degrees, but the actual angles differ due to variations in electronegativity and substituent size.

Explanation:

Polymerization and Lewis Structures

To draw the Lewis structure for the monomer tetrafluoroethylene (C2F4) used to make the polymer polytetrafluoroethylene (Teflon), we start by considering that carbon and fluorine both follow the octet rule, meaning that they both seek to be surrounded by eight electrons to reach a stable configuration. In C2F4, each carbon atom is double-bonded to the other carbon atom and single-bonded to two fluorine atoms. The hybridization of carbon in C2F4 is sp2 because it has three sigma bonds (one with the other carbon and two with fluorine atoms) and one pi bond (part of the double bond with the other carbon).

The ideal bond angles for an sp2 hybridized atom are 120 degrees. However, in the case of C2H4 and C2F4, the actual bond angles are 117.4 degrees for H-C-H and 112.4 degrees for F-C-F respectively. These deviations from the ideal angles can be attributed to the differences in electronegativity and size of the substituents, causing variations in electron cloud repulsions and thus slightly adjusting the bond angles.

Answer:

A mixture of 100. mL of 0.1 M HC3H5O3 and 50. mL of NaOH

Explanation:

The pH of a buffer solution is calculated using following relation

[tex]pH=pKa+log(\frac{salt}{acid} )[/tex]

Thus the pH of buffer solution will be near to the pKa of the acid used in making the buffer solution.

The pKa value of HC₃H₅O₃ acid is more closer to required pH = 4 than CH₃NH₃⁺ acid.

pKa = -log [Ka]

For HC₃H₅O₃

pKa = 3.1

For CH₃NH₃⁺

pKa = 10.64

pKb = 14-10.64 = 3.36 [Thus the pKb of this acid is also near to required pH value)

A mixture of 100. mL of 0.1 M HC3H5O3 and 50. mL of NaOH

Half of the acid will get neutralized by the given base and thus will result in equal concentration of both the weak acid and the salt making the pH just equal to the pKa value.

The branch of science that deals with the chemicals and the bond are called chemistry. there are two types of solution out of which one is acidic and the other is basic

The correct answer is C.

The equation used to solve the question is as follows:-

[tex]pH = pKa +log\frac{salt}{acid}[/tex]

Thus the pH of the buffer solution will be near to the pKa of the acid used in making the buffer solution because the salt is used in the question with respect to the acid.

The pKa value of [tex]HC_3H_5O_3[/tex]acid is closer to the required pH = 4 than [tex]CH_3NH_3^+[/tex]acid. [tex]pKa = -log [Ka]HC_3H_5O_3[/tex] , the pKa is 3.1

[tex]CH_3NH_3^+[/tex]the pKa is 10.64

The total pKb value is

= 14-10.6

= 3.36

Hence, the correct answer is C which is A mixture of 100 mL of 0.1 M HC3H5O3 and 50. mL of NaOH

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The question involves balancing acid-base reactions in chemistry. These are neutralization reactions. The balanced equations are: 1) H2SO4 (aq) + Ca(OH)2 (aq) --> 2H2O (l) + CaSO4(s), 2) HClO4 (aq) + KOH (aq) --> H2O (l) + KClO4(aq), 3) H2SO4 (aq) + 2NaOH (aq) --> 2H2O (l) + Na2SO4(aq).

The original equations are examples of acid-base reactions, specifically neutralization reactions. Here are the balanced equations:

In each of these reactions, the acid (H2SO4, HClO4) reacts with the base (Ca(OH)2, KOH, NaOH) to form water and a salt. The resulting phases of the products are indicated with each product (l for liquid, aq for aqueous, or s for solid).

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The given problems are examples of acid-base neutralization reactions where an acid reacts with a base to form water and a salt. The balanced equations for the reactions are: H2SO4 (aq) + Ca(OH)2 (aq) --> CaSO4 (s) + 2H2O (l), HClO4 (aq) + KOH (aq) --> KClO4 (aq) + H2O (l), and H2SO4 (aq) + 2NaOH (aq) --> Na2SO4 (aq) + 2H2O (l).

The reactions you are asking about are examples of acid-base neutralization reactions. In these reactions, an acid reacts with a base to produce water and a salt.

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Answer:

(A) endothermic

(A) Yes, absorbed

Explanation:

Let's consider the following thermochemical equation.

2 Fe₂O₃(s) ⇒ 4 FeO(s) + O₂(g)  ΔH = 560 kJ

Since ΔH > 0, the reaction is endothermic.

We can establish the following relations:

Suppose 66.6 g of Fe₂O₃ react. The heat absorbed is:

[tex]66.6g.\frac{1mol}{160g} .\frac{560kJ}{2mol} =117kJ[/tex]

Final answer:

The reaction 2Fe2O3(s) to 4FeO(s) + O2(g) is endothermic with a \\Delta H of +560 kJ, meaning it absorbs heat. For 66.6 g of Fe2O3 react, heat will be absorbed.

Explanation:

When assessing a chemical reaction's energy change, the sign of \\Delta H\ indicates whether the reaction is exothermic or endothermic. For the reaction given, 2Fe2O3(s) \\rightarrow\ 4FeO(s) + O2(g), the \\Delta H\ is 560 kJ. This positive value means that the reaction is endothermic, as it absorbs heat from the surroundings.

For the specific amount of 66.6 g of Fe2O3, since the reaction is endothermic, energy in the form of heat will indeed be absorbed. Therefore, heat will be absorbed when 66.6 g of Fe2O3 react.

Answer:

We need 42.4 mL of benzene to produce 1.5 *10³ kJ of heat

Explanation:

Step 1: Data given

Density of benzene = 0.88 g/mL

Molar mass of benzene = 78.11 g/mol

Heat produced = 1.5 * 10³ kJ

Step 2: The balanced equation

2 C6H6(l) + 15 O2(g) → 12 CO2(g) + 6 H2O(g)         ΔH°rxn = -6278 kJ

Step 3: Calculate moles of benzen

1.5 * 10³ kJ * (2 mol C6H6 / 6278 kJ) = 0.478 mol C6H6

Step 4: Calculate mass of benzene

Mass benzene : moles benzene * molar mass benzene

Mass benzene= 0.478 * 78.11 g

Mass of benzene = 37.34 grams

Step 5: Calculate volume of benzene

Volume benzene = mass / density

Volume benzene = 37.34 grams / 0.88g/mL

Volume benzene = 42.4 mL

We need 42.4 mL of benzene to produce 1.5 *10³ kJ of heat

The volume of benzene required is 42.5 mL of benzene.

The equation of the reaction is;  2C6H6(l) + 15 O2(g) → 12 CO2(g) + 6 H2O(g) ΔH°rxn = -6278 kJ

If 2 mole of benzene produces -6278 kJ of heat

x moles of benzene produces 1.5 x 103 kJ

x =  2 mole ×  -1.5 x 10^3 kJ/ -6278 kJ

x = 0.48 moles of benzene

The mass of benzene required = number of moles of benzene x molar mass of benzene

Molar mass of benzene = 78 g/mol

Mass of benzene required = 0.48 moles of benzene × 78 g/mol

= 37.44 g

Density of benzene = 0.88 g/mL

But; density = mass/volume

Volume = mass/density

volume = 37.44 g/0.88 g/mL

volume = 42.5 mL of benzene

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Answer:

The heat produced is -15,1kJ

Explanation:

For the reaction:

2SO₂+O₂ → 2SO₃

The enthalpy of reaction is:

ΔHr = 2ΔHf SO₃ - 2ΔHf SO₂

As ΔHf SO₃ = -395,7kJ and ΔHf SO₂ = -296,8kJ

ΔHr = -197,8kJ

Using n=PV/RT, the moles of reaction are:

[tex]n = \frac{1,00atm*3,75L}{0,082atmL/molK*298,15K}[/tex] = 0,153 moles of reaction

As 2 moles of reaction produce -197,8kJ of heat, 0,153moles produce:

0,153mol×[tex]\frac{-197,8kJ}{2mol}[/tex] = -15,1kJ

I hope it helps!

14.8 KJ/mol of heat energy is produced when a volume of 3.75 L of SO2(g) is converted to 3.75 L of SO3(g).

The equation of the reaction is;

2SO2(g) + O2(g) ⇄ 2SO3(g)

We have the following information;

ΔHf SO2(g) = -296.8 KJ/mol

ΔHf O2(g) = 0 KJ/mol

ΔHf SO3(g) =  -395.7 kJ/mol

We can calculate the heat of reaction ΔHrxn from;

ΔHrxn = [ΔHf (products) - ΔHf (reactants)]

ΔHrxn = [2( -395.7 kJ/mol)] - [2(-296.8 KJ/mol) + 0 KJ/mol]

ΔHrxn = (-791.4  kJ/mol) + 593.6 KJ/mol

ΔHrxn = -197.8 KJ/mol

We can find the number of moles of SO2 reacted using the ideal gas equation;

P = 1.00 atm

T = 25.0°C + 273 = 298 K

n = ?

V = 3.75 L

R = 0.082 atmLK-1mol-1

So,

PV = nRT

n = PV/RT

n = 1.00 atm × 3.75 L/0.082 atmLK-1mol-1 ×   298 K

n = 0.15 moles

If 2 moles of SO2 produced -197.8 KJ/mol

0.15 moles of SO2 will produce  0.15 moles  × (-197.8 KJ/mol)/ 2 moles

= -14.8 KJ/mol

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In the ATP hydrolysis reaction, the O-P bond in ATP is broken, requiring a lot of energy. The OH-P bond formed in the reaction is strong and does not release energy.

In the ATP hydrolysis reaction, the O-P bond in ATP is broken, which requires a lot of energy. This breaking of the bond releases energy that is stored in the bond. Therefore, it takes a lot of energy to break the O-P bond in ATP.

The OH-P bond that is formed in the reaction is a strong bond. The formation of this bond is not responsible for releasing energy in the reaction.

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Final answer:

The breaking of the high-energy phosphate bond in ATP during hydrolysis releases energy. The OH-P bond formed in the reaction is strong, but its formation is not the source of energy release. The correct statement is 1) "The OH-P bond that is formed in the reaction is a strong bond."

Explanation:

ATP hydrolysis is an exothermic reaction where energy is released from the breaking of the high-energy phosphate bond in ATP, producing ADP and inorganic phosphate (Pi). The bond between the phosphates in ATP (phosphoanhydride bonds) is considered high-energy, not because it takes a lot of energy to break, but because the products of the reaction (ADP and Pi) have considerably lower free energy than ATP and a water molecule. Hence, the breaking of the O-P bond in ATP releases the energy that was stored in the bond.

The OH-P bond that forms when Pi is created during ATP hydrolysis is actually a strong bond, and the formation of this bond is not responsible for the release of energy, rather it is the breaking of the high-energy bond in ATP that releases energy.

Answer:

The Ka for this acid is 1.4 * 10^-4 (option C)

Explanation:

Step 1: Data given

In a 0.20M aqueous solution, lactic acid is 2.6% dissociated.

Step 2: The equation for the dissociation of HAc is:

HAc ⇌ H+ + Ac¯

The Ka expression is:

Ka = ([H+] [Ac¯]) / [HAc]

1) [H+] using the concentration and the percent dissociation:

(0.026) (0.2) = 0.0052 M

2) Calculate [Ac-] and [H+]

[Ac¯] = [H+] = x = 0.0052 M

3) Calculate [HAc]

[HAc] = 0.20M - x ( since x << 0.20, we can assume [HAc]  = 0.20 M

4) Calculate Ka

Ka= [( 0.0052) ( 0.0052)] / 0.20

Ka = 0.0001352 = 1.4 * 10^-4

The Ka for this acid is 1.4 * 10^-4

Final answer:

The value of Ka for lactic acid, given that a 0.20 M solution is 2.6% dissociated, can be calculated using the concentration of dissociated ions; the closest value to our calculation is 1.4x10^-4.

Explanation:

When you exercise, the burning sensation in your muscles is often due to the buildup of lactic acid. To find the acid dissociation constant (Ka) for lactic acid given a 0.20 M solution that is 2.6% dissociated, we use the dissociation equation of a weak acid:

HC₃H₅O₃ → H⁺ + C₃H₅O₃⁻

The concentration of H⁺ and C₃H₅O₃⁻ will also be 0.0052 M, since it's a one-to-one dissociation. Thus, the expression for Ka becomes:

The closest answer to our calculated Ka value is C.) 1.4x10^-4.

Answer:

A mole is 6.02 X 1023 of any particles and the SI unit for measuring the quantity of a substance

Explanation:

Forming dimers, like acetic acid's molecules under specific conditions, would double the experimental molar mass as the measurements would account for the mass of the dimer, which is twice that of the monomer.

When molecules form dimers, such as acetic acid (CH3COOH) under certain conditions, it can significantly impact the determination of the molar mass experimentally. Typically, the molar mass is determined by measuring the mass of a certain number of moles of a substance. However, if the molecules are forming dimers, the actual molar mass calculated will be double the expected molar mass of the monomer because the experiments would be measuring the mass of the dimer (A2) rather than the individual monomer (A).

In other words, the experimental molar mass would be higher than it should be if one assumes that no dimers are present. This is because the mass being measured corresponds to the molar mass of the dimer rather than that of the monomer. When dealing with substances that can form dimers, this possibility must be taken into account to ensure accurate molar mass determination.

The formation of dimers in a liquid affects the experimental molar mass by potentially doubling the value if the molecular associations are not accounted for, leading to a measured molar mass that reflects the dimer rather than the monomer.

When molecules in a liquid form dimers due to strong intermolecular attractions, such as hydrogen bonding, the observed experimental molar mass would be affected. If the tendency to form dimers is not accounted for in molar mass determination, the measured molar mass would be roughly double that of the monomeric form because the dimer is made up of two monomer units. For example, in acetic acid, when dimers are formed, the molar mass derived from experimental measurements would reflect the mass of the dimer, rather than the monomer.

In cases where dissociation occurs, like A2 dissociating into two A molecules in solution, monitoring the concentration of both the dimer and monomer can be critical. Incorrect assumptions about the degree of dimerization can lead to inaccurate molar mass calculations.

Answer : The correct answer is "No solution".

Explanation :

As we are given that 38.1 % w/w solution of heptane in chloroform. That means 38.1 gram of heptane present in 100 gram of solution.

Now we have to determine the mass of solution for 65.0 grams of hepatne.

As, 38.1 grams of heptane present in 100 grams of solution

So, 65.0 grams of heptane present in [tex]\frac{65.0}{38.1}\times 100=171[/tex] grams of solution

Since, there is only 20.0 grams of solution available. That means, there is not enough solution.

Thus, the correct answer is "No solution".

Final answer:

The student would need 170.6g of the 38.1% w/w heptane solution to obtain 65.0g of heptane. However, the student only has 20.0g of solution, which is not enough to provide the required amount of heptane, so the student does not have a viable solution.

Explanation:

The student needs to calculate the mass of solution to use to obtain 65.0g of heptane from a 38.1% w/w solution of heptane in chloroform. The weight/weight percentage (w/w%) indicates that for every 100g of solution, there are 38.1g of heptane. To find the mass of the solution needed to obtain 65.0g of heptane, the following calculation can be performed:

m = (desired mass of heptane) / (percentage of heptane in solution as a decimal)

m = 65.0g / 0.381

m = 170.6g

The student would need to use 170.6g of the 38.1% w/w heptane solution to obtain the required amount of pure heptane. However, since the student only has 20.0g of solution, there is not enough to obtain 65.0g of heptane without obtaining more solution. Therefore, the student cannot proceed with the experiment as is and must either get more solution or adjust the experiment.

Answer:

The missing particle is [tex]_{103}^{259}\textrm{Lr}[/tex].

Explanation:

In a nuclear reaction, the total mass and total atomic number remains the same.

For the given fission reaction:

[tex]^{252}_{98}\textrm{Cf}+^{10}_{5}\textrm{B}\rightarrow ^A_Z\textrm{X}+3^1_0\textrm{n}[/tex]

To calculate A:

Total mass on reactant side = total mass on product side

252 +10 = A+ 3

A = 259

To calculate Z:

Total atomic number on reactant side = total atomic number on product side

98 +5 = Z + 0

Z = 103

Hence, the isotopic symbol of unknown element is [tex]_{103}^{259}\textrm{Lr}[/tex]

(a) [tex]\[ \frac{252}{98}\text{Cf} + \frac{10}{5}\text{B} \rightarrow 3 \frac{1}{0}\text{n} + \frac{259}{103}\text{Lr} \][/tex]

(b) [tex]\[ \frac{2}{1}\text{H} + \frac{3}{2}\text{He} \rightarrow \frac{4}{2}\text{He} + \frac{1}{1}\text{H} \][/tex]

(c) [tex]\[ \frac{1}{1}\text{H} + \frac{11}{5}\text{B} \rightarrow 3 \frac{4}{2}\text{He} \][/tex]

To complete and balance the nuclear equations, we need to ensure that both the atomic numbers (proton numbers) and mass numbers (nucleon numbers) are conserved on both sides of each equation.

(a) [tex]\( \frac{252}{98}\text{Cf} + \frac{10}{5}\text{B} \rightarrow 3 \frac{1}{0}\text{n} + ? \)[/tex]

First, determine the total atomic and mass numbers on the left side:

- Cf: Atomic number = 98, Mass number = 252

- B: Atomic number = 5, Mass number = 10

Sum of atomic numbers on the left side: 98 + 5 = 103

Sum of mass numbers on the left side: 252 + 10 = 262

On the right side, we have 3 neutrons:

- Each neutron: Atomic number = 0, Mass number = 1

- Total for neutrons: Atomic number = 0, Mass number = 3

So, the missing particle must balance the equation:

- Atomic number: 103 - 0 = 103

- Mass number: 262 - 3 = 259

Thus, the missing particle is [tex]\( \frac{259}{103}\text{Lr} \)[/tex] (Lawrencium).

The complete equation is:

[tex]\[ \frac{252}{98}\text{Cf} + \frac{10}{5}\text{B} \rightarrow 3 \frac{1}{0}\text{n} + \frac{259}{103}\text{Lr} \][/tex]

(b) [tex]\( \frac{2}{1}\text{H} + \frac{3}{2}\text{He} \rightarrow \frac{4}{2}\text{He} + ? \)[/tex]

First, determine the total atomic and mass numbers on the left side:

- H: Atomic number = 1, Mass number = 2

- He: Atomic number = 2, Mass number = 3

Sum of atomic numbers on the left side: 1 + 2 = 3

Sum of mass numbers on the left side: 2 + 3 = 5

On the right side, we have one helium-4 nucleus:

- He: Atomic number = 2, Mass number = 4

So, the missing particle must balance the equation:

- Atomic number: 3 - 2 = 1

- Mass number: 5 - 4 = 1

Thus, the missing particle is [tex]\( \frac{1}{1}\text{H} \)[/tex] (a proton).

The complete equation is:

[tex]\[ \frac{2}{1}\text{H} + \frac{3}{2}\text{He} \rightarrow \frac{4}{2}\text{He} + \frac{1}{1}\text{H} \][/tex]

(c) [tex]\( \frac{1}{1}\text{H} + \frac{11}{5}\text{B} \rightarrow 3? \)[/tex]

First, determine the total atomic and mass numbers on the left side:

- H: Atomic number = 1, Mass number = 1

- B: Atomic number = 5, Mass number = 11

Sum of atomic numbers on the left side: 1 + 5 = 6

Sum of mass numbers on the left side: 1 + 11 = 12

Let ?  be [tex]\( \frac{4}{2}\text{He} \) (alpha particle)[/tex]. Since we need 3 of these particles:

- Each He: Atomic number = 2, Mass number = 4

- Total for 3 He: Atomic number = 6, Mass number = 12

So, the 3 particles are 3 [tex]\( \frac{4}{2}\text{He} \)[/tex] (3 alpha particles).

The complete equation is:

[tex]\[ \frac{1}{1}\text{H} + \frac{11}{5}\text{B} \rightarrow 3 \frac{4}{2}\text{He} \][/tex]

Complete Question:

Complete and balance the following nuclear equations by supplying the missing particle:

(a) 252/98Cf + 10/5B -> 3 1/0n + ?

(b) 2/1H + 3/2He -> 4/2He + ?

(c) 1/1H + 11/5B -> 3?

Answer:

The molar mass of the gas is 140.86 g/mol

Explanation:

Step 1: Data given

Mass of the gas = 0.555 grams

Volume of the gas = 117 mL = 0.117 L

Temperature = 85 °C

Pressure = 0.99 atm

Step 2: Calculate the number of moles

p*V = n*R*T

⇒ with p = the pressure of the gas = 0.99 atm

⇒ with V = the volume = 0.117 L

⇒ with n = the number of moles

⇒ with R = the gas constant = 0.08206 L*atm/K*mol

⇒ with T = the temperature of the gas = 85 °C = 358.15 Kelvin

n = (p*V)/(R*T)

n = (0.99 * 0.117)/(0.08206 * 358.15)

n = 0.00394 moles

Step 3: Calculate molar mass of the gas

Molar mass = mass / moles

Molar mass = 0.555 grams / 0.00394 moles

Molar mass = 140.86 g/mol

The molar mass of the gas is 140.86 g/mol

Answer: 0.04 moles

Explanation:

pV = nRT

p=pressure = 0.99atm

v = volume = 117ml = 0.117L

n = number of moles = n

T = temperature = 85 +273 = 358k

R = rate constant  = 0.082 L.atm/kmol

n = pV/RT = 0.99 X 0.117/(0.082 X 358)

    = 0.004 moles

Answer: [tex]2.2326\times 10^{-3}[/tex] moles

Explanation:

We are given:

Moles of electron = 1 mole

According to mole concept:

1 mole of an atom contains [tex]6.022\times 10^{23}[/tex] number of particles.

We know that:

Charge on 1 electron = [tex]1.6\times 10^{-19}C[/tex]

Charge on 1 mole of electrons = [tex]1.6\times 10^{-19}\times 6.022\times 10^{23}=96500C[/tex]

The metal being plated has a +4 charge, thus the equation will be:

[tex]M^{4+}+4e^-\rightarrow M[/tex]

[tex]4\times 96500C[/tex] of electricity deposits = 1 mole of metal

Thus 861.8 C of electricity deposits =[tex]\frac{1}{4\times 96500}\times 861.8=2.2326\times 10^{-3}[/tex] moles of metal

Thus [tex]2.2326\times 10^{-3}[/tex] moles of metal should be plated

The number of moles of the metal deposited is 0.0022 moles of metal.

The term electroplating refers to the use of one metal to cover the surface of another metal. Let the metal in question be M, the equation of the reaction is; M^4+(aq) + 4e -----> M(s).

1 mole of the metal is deposited by 4( 96,500) C

x moles will be  deposited by 861.8 C

x = 1 mole * 861.8 C/ 4( 96,500) C

x = 0.0022 moles of metal

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Answer:

The true stress required = 379 MPa

Explanation:

True Stress is the ratio of the internal resistive force to the instantaneous cross-sectional area of the specimen. True Strain is the natural log to the extended length after which load applied to the original length. The cold working stress – strain curve relation is as follows,

σ(t) = K (ε(t))ⁿ, σ(t) is the true stress, ε(t) is the true strain, K is the strength coefficient and n is the strain hardening exponent

True strain is given  by

Epsilon t =㏑ (l/l₀)

Substitute㏑(l/l₀) for ε(t)

σ(t) = K(㏑(l/l₀))ⁿ

Given values l₀ = 49.7mm, l =51.7mm , n =0.2 , σ(t) =379Mpa

379 x 10⁶ = K (㏑(51.7/49.7))^0.2

K = 379 x 10⁶/(㏑(51.7/49.7))^0.2

K = 723.48 MPa

Knowing the constant value would be same as the same material is being used in the second test, we can find out the true stress using the above formula replacing the value of the constant.

σ(t) = K(㏑(l/l₀))ⁿ

l₀ = 49.7mm, l = 51.7mm, n = 0.2, K = 723.48Mpa

σ(t) = 723.48 x 106 x (㏑(51.7/49.7))^0.2

σ(t) = 379 MPa

The true stress necessary to plastically elongate the specimen is 379 MPa.

Answer:i ea

Explanation:

Answer:

The statements are definitions to chromatography terms which have been highlighted below.

Explanation:

Match the chromatography term with its definition.

Volumetric Flow Rate = The volume of solvent traveling through the column per unit time.

Retention time = The elapsed time between sample injection and detection.

Adjusted Retention Time = The time required by a retained solute to travel through the column beyond the time required by the un -retained solvent.

Linear Flow Rate = The distance traveled by the solvent per unit time.

Retention factor = Describes the amount of time that a sample spends in the stationary phase relative to the mobile phase. It is sometimes also called the capacity factor or capacity ratio.

Relative Volume = Volume of the mobile phase required to elute a solute from the column.

Relative Retention = Ratio of the adjusted retention times or retention factors of two solutes. It is sometimes also called the separation factor.

Partition coefficient = The ratio of the solute concentrations in the mobile and stationary phases.

Chromatography is a laboratory technique used to separate and analyze the components of a mixture based on their different affinities for a stationary phase and a mobile phase. The different terms in chromatography can be defined as given below-

The volume of solvent traveling through the column per unit time - Flow rate

The elapsed time between sample injection and detection - Retention time

The time required by a retained solute to travel through the column beyond the time required by the unretained solvent - Adjusted retention time

The distance traveled by the solvent per unit time - Velocity

Describes the amount of time that a sample spends in the stationary phase relative to the mobile phase. It is sometimes also called the capacity factor or capacity ratio - Retention factor

Volume of the mobile phase required to elute a solute from the column - Elution volume

Ratio of the adjusted retention times or retention factors of two solutes. It is sometimes also called the separation factor - Selectivity factor

The ratio of the solute concentrations in the mobile and stationary phases - Distribution coefficient

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Answer:

69.8 kilo Pasacl is the pressure of the hydrogen gas.

Explanation:

[tex]Mg+2HCl\rightarrow MgCl_2+H_2[/tex]

Pressure at which hydrogen gas collected = p = 101.2 kilo Pascals

Vapor pressure water = [tex]p^o[/tex] = 31.4 kilo Pascals

The pressure of hydrogen gas = P

The pressure at which gas was collected was sum of vapor pressure of water and hydrogen gas.

[tex]p=P+p^o[/tex]

[tex]P =p-p^o=101.2 kPa-31.4 kPa=69.8 kPa[/tex]

69.8 kilo Pasacl is the pressure of the hydrogen gas.

The pressure of the hydrogen gas is 69.8 kPa.

The pressure of the hydrogen gas can be calculated by subtracting the vapor pressure of water from the total pressure. In this case, the total pressure is 101.2 kPa and the vapor pressure of water is 31.4 kPa. So, the pressure of the hydrogen gas is 101.2 kPa - 31.4 kPa = 69.8 kPa.

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The volume of KOH must be added to 500 ml of the acidic solution to neutralize all of the acids is equal to 968 ml.

A neutralization reaction can be described as a chemical reaction in which an acid and base react with each other to produce salt and water.

The neutralization reaction between HCl and NaOH:

HCl    +   KOH   →  KCl   +   H₂O

The concentration of HCl solution = 0.100M

The volume of the solution =  500 ml = 0.5 L

The number of moles of HCl = 0.100 × 0.5 = 0.05 mol

The neutralization reaction between H₂SO₄ and KOH:

H₂SO₄    +  KOH   →   K₂SO₄   +   2H₂O

The concentration of H₂SO₄ solution = 0.100M

The volume of the acidic solution =  500 ml = 0.5 L

The number of moles of H₂SO₄ = 0.210 × 0.5 = 0.105 mol

Total number of moles needed to neutralize = 0.05 + 0.105 = 0.155 mol

The concentration of KOH solution = 0.150 M

The volume of the KOH solution = M/n

V = 0.150/0.155

V = 0.968 L

V = 968 ml

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Answer:

The dipole moment of H-C bond will be smaller than that of an H-I bond.

Explanation:

The electronegativity of iodine is greater than that of hydrogen.As a result the iodine atom tends to attract the bond electron pair of H-I bond towards itself creating a bond dipole which does not occur in case of H-C bond as the electronegativity of carbon and hydrogen are almost same.

   That"s why dipole moment of H-C bond is smaller than that of H-I bond.

Answer: A

Explanation:

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Answer:

a. Isopropyl pentanoate.

Explanation:

Hello,

In this case, such esterification is:

[tex]CH_3CH_2CH_2CH_2COOH+OHCH(CH_3)_2\rightarrow CH_3CH_2CH_2CH_2COOCH(CH_3)_2+H_2O[/tex]

Wherein the first reactant is the pentanoic acid, the second one the isopropanol and the first product is the result, which is a. isopropyl pentanoate. This is because the isopropyl get separated from the hydroxile and bonds with the carboxile group of the pentanoic acid by also releasing water as the byproduct.

Best regards.

The theoretical yield of sodium chloride formed from the reaction of 3.3 g of hydrochloric acid and 6.7 g of sodium hydroxide is 5.3 g

How to obtain the theoretical yield of sodium chloride?

We shall begin by determining the limiting reactant for the reaction of 3.3 g of hydrochloric acid and 6.7 g of sodium hydroxide. This is shown below:

HCl + NaOH -> NaCl + H₂O

From the balanced equation above,

36.5 g of HCl reacted with 40 g of NaOH

Therefore,

3.3 g of HCl will react with = (3.3 × 40) / 36.5 = 3.6 g of NaOH

Now, we can see that only 3.6 g of NaOH reacted with 3.3 g of HCl

Thus, the limiting reactant is HCl

Finally, we shall calculate the theoretical yield of sodium chloride. Details below:

HCl + NaOH -> NaCl + H₂O

From the balanced equation above,

36.5 g of HCl reacted to produce 58.5 of NaCl

Therefore,

3.3 g of HCl will react to produce = [tex]\frac{3.3\ \times\ 58.5}{36.5}[/tex] = 5.3 g of NaCl

In conclusion, theoretical yield of sodium chloride is 5.3 g

Complete question:

Aqueous hydrochloric acid reacts with solid sodium hydroxide to produce aqueous sodium chloride and liquid water.

What is the theoretical yield of sodium chloride formed from the reaction of 3.3 g of hydrochloric acid and 6.7 g of sodium hydroxide.? Round your answer to significant figure

Answer:

pH= 11.49

Explanation:

Ethanolamine is an organic chemical compound of the formula; HOCH2CH2NH2. Ethanolamine, HOCH2CH2NH2 is a weak base.

From the question, the parameters given are; the concentration of ethanolamine which is = 0.30M, pH value= ??, pOH value= ??, kb=3.2 ×10^-5

Using the formula below;

[OH^-]=√(kb×molarity)----------------------------------------------------------------------------------------------------------(1)

[OH^-] =√(3.2×10^-5 × 0.30M)

[OH^-]= √(9.6×10^-6)

[OH^-]=3.0984×10^-3

pOH= -log[OH^-]

pOH= -log 3.1×10^-3

pOH= 3-log 3.1

pH= 14-pOH

pH= 14-(3-log3.1)

pH= 11+log 3.1

pH= 11+ 0.4914

pH= 11.49

The pH of the ethanolamine solution has been 11.5.

The pH of the solution has been defined as the concentration of hydrogen ion in the solution.

The pH has been the difference of pOH from 14.

The ethanolamine has been a weak base. The OH concentration of ethanolamine has been given as:

[tex]\rm OH^-=\sqrt{Kb\;\times\;Molarity}[/tex]

The Kb of sample has been given as [tex]3.2\;\times\;10^-^5[/tex]

The molarity of sample has been, 0.3 M.

Substituting the values for hydroxide ion concentration:

[tex]\rm OH^-=\sqrt{3.2\;\times\;10^-^5\;\times\;0.3}\\OH^-=3.098\;\times\;10^-^3[/tex]

The pOH has been the negative logarithmic values of hydroxide ion concentration. The pOH has been given as:

[tex]\rm pOH=-log\;OH^-\\pOH=-log\;3.098\;\times\;10^-^3\\pOH=2.5[/tex]

The pOH of the sample has been 2.5.

The pH of ethanolamine sample has been given as:

[tex]\rm pH=14-pOH\\pH=14-2.5\\pH=11.5[/tex]

The pH of the ethanolamine solution has been 11.5.

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Answer:

The answer to this question has been described in details on the screenshots attached to this question.

Thanks. Hope it helps

The final temperature of the mixed solution is approximately 19.5°C, assuming complete reaction and constant heat capacity of the solution.

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Answer:

kf = 1.16 x 10¹⁸

Explanation:

Step 1: [Ni(H₂O)₆]²⁺  + 1en → [Ni(H₂O)₄(en)]²⁺  ΔG°1 = -42.9 kJmol⁻¹

Step 2: [Ni(H₂O)₄(en)]²⁺  + 1en → [Ni(H₂O)₂(en)₂]²⁺  ΔG°2 = -35.8 kJmol⁻¹

Step 3: [Ni(H₂O)₂(en)₂]²⁺ + 1en →  [Ni(en)₃]²⁺  ΔG°3 = -24.3 kJmol⁻¹

________________________________________________________

Overall reaction: [Ni(H₂O)₆]²⁺  + 3en → [Ni(en)₃]²⁺  ΔG°r

ΔG°r = ΔG°1 + ΔG°2 + ΔG°3

ΔG°r = -42.9 - 35.8 - 24.3

ΔG°r = -103.0 kJmol⁻¹

ΔG°r = -RTlnKf

-103,000 Jmol⁻¹ =  - 8.31 J.K⁻¹mol⁻¹ x 298 K x lnKf

kf = e ^(-103,000/-8.31x298)

kf = e ^41.59

kf = 1.16 x 10¹⁸

Answer:

Less

Explanation:

The bond angle in NH3 is greater than the bond angle in PH3.

According to the valence shell electron pair repulsion theory, the shape of molecules depends on the number of electron pairs that surround the central atom. The electronegativity of the central atom determines the bond angle of the molecule. The greater the electronegativitty of the central atom, the greater the bond angle.

Nitrogen is more electronegative than Phosphorus hence, the bond angle in NH3 is greater than the bond angle in PH3.

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Answer: The standard enthalpy of the reaction is -248.78 kJ/mol

Explanation:

The heat released by the reaction is absorbed by the calorimeter and the solution.

The chemical equation used to calculate the heat released follows:

[tex]q=c\times \Delta T[/tex]

where,

c = heat capacity of calorimeter = 448 J/K

[tex]\Delta T[/tex] = change in temperature = 21.1 K

Putting values in above equation, we get:

[tex]q=448J/K\times 21.1K=9452.8J[/tex]

Sign convention of heat:

When heat is absorbed, the sign of heat is taken to be positive and when heat is released, the sign of heat is taken to be negative.

To calculate the number of moles, we use the equation:

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

Given mass of zinc = 2.50 g

Molar mass of zinc = 65.4 g/mol

Putting values in above equation, we get:

[tex]\text{Moles of zinc}=\frac{2.50g}{65.4g/mol}=0.038mol[/tex]

To calculate the standard enthalpy of the reaction, we use the equation:

[tex]\Delta H^o_{rxn}=\frac{q}{n}[/tex]

where,

[tex]q[/tex] = amount of heat released = -9452.8 J

n = number of moles = 0.038 moles

[tex]\Delta H^o_{rxn}[/tex] = standard enthalpy of the reaction

Putting values in above equation, we get:

[tex]\Delta H^o_{rxn}=\frac{-9452.8J}{0.038mol}=-248757.9J/mol=-248.78kJ/mol[/tex]

Conversion factor used:  1 kJ = 1000 J

Hence, the standard enthalpy of the reaction is -248.78 kJ/mol

The Brønsted acid-base equation for the reaction between vinegar (acetic acid, HC2H3O2) and bleach (sodium hypochlorite, NaClO) is HC2H3O2 + NaClO → C2H3O2^- + HClO, where HC2H3O2 is the acid and NaClO is the base.

The acid-base reaction between vinegar (which contains acetic acid, HC2H3O2) and bleach (which contains sodium hypochlorite, NaClO) can be represented as a Brønsted acid-base equation:

HC2H3O2 + NaClO → C2H3O2^- + HClO

In this reaction, HC2H3O2 is the acid as it donates a proton (H^+) and NaClO is the base as it accepts a proton (H+). Remember, spectator ions, such as Na^+ from sodium hypochlorite, have been omitted because they don't participate in the reaction.

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Answer:

A. 433 years and 63 days

B. Iodine

C. 0.125mg

D. 1.00mg

Explanation:

A. Americium

The formula of a radioactive decay constant half life is t = 0.693/k

Where k is the decay constant.

For americium, k = 0.0016

t = 0.693/0.0016 = 433.125 apprx 433 years

For iodine, k = 0.011

Half life = 0.693/0.011 = 63 days.

B. Iodine decays at a faster rate.

C. After three half lives

For both, first half life yields a mass of 0.5mg, next yields 0.25mg, next yield 0.125mg

D. 1.00mg still remains.

Half life is high for both so the decay after one day is insignificant.

a) The half-lives of Americium-241 and Iodine-125 are 433 years and 63 days, respectively.

b) Iodine-125 decays faster.

c) After three half-lives, 0.125 mg remains.

d) After 4 days, nearly 1.00 mg of Americium-241 and 0.957 mg of Iodine-125 remain.

To answer the given questions regarding the radioactive decay of Americium-241 and Iodine-125:

(a) Half-lives

For a first-order reaction, the half-life (t1/2) can be calculated using the equation:

t1/2 = 0.693 / k

For Americium-241:
k = 1.6 × 10⁻³ yr⁻¹
t1/2 = 0.693 / (1.6 × 10⁻³) = 433 years

For Iodine-125:
k = 0.011 day⁻¹
t1/2 = 0.693 / 0.011 = 63 days

(b) Decay Rate

Since the half-life of Iodine-125 is shorter (63 days) compared to Americium-241 (433 years), Iodine-125 decays at a faster rate.

(c) Remaining Sample After Three Half-lives

After three half-lives, the remaining amount of a radioactive isotope can be calculated using:

Remaining Amount = Initial Amount / (23)
Remaining Amount = 1.00 mg / 8 = 0.125 mg

Therefore, for both isotopes, 0.125 mg remains after three half-lives.

(d) Remaining Sample After 4 Days

For Americium-241 (with t1/2 about 433 years), 4 days is negligible, so nearly the entire 1.00 mg remains.

For Iodine-125, using the first-order decay formula:

N = N₀ e-kt

t = 4 days, k = 0.011 day⁻¹

N = 1.00 mg × e-(0.011 × 4) ≈ 1.00 mg × e-0.044 ≈ 1.00 mg × 0.957 = 0.957 mg

Thus, after 4 days, 0.957 mg of Iodine-125 remains.

Answer:

[tex]Energy=1\times 10^{15}h\ J[/tex]

Explanation:

Considering:-

[tex]E=\frac {h\times c}{\lambda}[/tex]

Where,  

h is Planck's constant having value [tex]6.626\times 10^{-34}\ Js[/tex]

c is the speed of light having value [tex]3\times 10^8\ m/s[/tex]

[tex]\lambda[/tex] is the wavelength of the light

Given, Wavelength = 300 nm

Also, 1 m = [tex]10^{-9}[/tex] nm

So,  

Wavelength = [tex]300\times 10^{-9}[/tex] m

Applying in the equation as:-

[tex]E=\frac {h\times c}{\lambda}[/tex]

[tex]E=\frac{h\times 3\times 10^8}{300\times 10^{-9}}\ J[/tex]

[tex]Energy=1\times 10^{15}h\ J[/tex]

Answer:

1) When 6.97 grams of sodium(s) react with excess water(l), 56.0 kJ of energy are evolved.

2) When 10.4 grams of carbon monoxide(g) react with excess water(l), 1.04 kJ of energy are absorbed.

Explanation:

1) The following thermochemical equation is for the reaction of sodium(s) with water(l) to form sodium hydroxide(aq) and hydrogen(g).

2 Na(s) + 2H₂O(l) ⇒ 2NaOH(aq) + H₂(g) ΔH = -369 kJ

The enthalpy of the reaction is negative, which means that 369 kJ of energy are evolved per 2 moles of sodium. The energy evolved for 6.97 g of Na (molar mass 22.98 g/mol) is:

[tex]6.97g.\frac{1mol}{22.98g} .\frac{-369kJ}{2mol} =-56.0kJ[/tex]

2) The following thermochemical equation is for the reaction of carbon monoxide(g) with water(l) to form carbon dioxide(g) and hydrogen(g).

CO(g) + H₂O(l) ⇒ CO₂(g) + H₂(g)  ΔH = 2.80 kJ

The enthalpy of the reaction is positive, which means that 2.80 kJ of energy are absorbed per mole of carbon monoxide. The energy evolved for 10.4 g of CO (molar mass 28.01 g/mol) is:

[tex]10.4g.\frac{1mol}{28.01g} .\frac{2.80kJ}{mol} =1.04kJ[/tex]

To find the energy evolved in each reaction, use stoichiometry and the molar mass of the reactant to calculate the moles reacted and then use the stoichiometric ratio between the reactant and energy.

For the first reaction, we are given the thermochemical equation 2Na(s) + 2H2O(l)2NaOH(aq) + H2(g) with ΔH = -369 kJ. To find the energy evolved when 6.97 grams of sodium react with excess water, we need to use stoichiometry and the molar mass of sodium to calculate the moles of sodium reacted. Then, we can use the stoichiometric ratio between sodium and energy to find the energy evolved.

For the second reaction, we are given the thermochemical equation CO(g) + H2O(l)CO2(g) + H2(g) with ΔH = 2.80 kJ. To find the energy evolved when 10.4 grams of carbon monoxide react with excess water, we need to use stoichiometry and the molar mass of carbon monoxide to calculate the moles of carbon monoxide reacted. Then, we can use the stoichiometric ratio between carbon monoxide and energy to find the energy evolved.

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