Question 1

If a reaction with a negative value of ΔS is nonspontaneous at constant temperature and pressure,

Accepted Answer

A) ΔG is negative and ΔH may be positive or negative. 
B) ΔG is negative and ΔH is positive. 
C) ΔG is positive and ΔH may be positive or negative. 
D) ΔG is positive and ΔH is positive. 
A) ΔG is negative and ΔH may be positive or negative. 
B) ΔG is negative and ΔH is positive. 
C) ΔG is positive and ΔH may be positive or negative. 
D) ΔG is positive and ΔH is positive. C

Question 2

The following drawing is a representation of a reaction for which ΔH° = +62 kJ.This reaction is likely to be

Accepted Answer

A) nonspontaneous at all temperatures. 
B) nonspontaneous at low temperatures and spontaneous at high temperatures. 
C) spontaneous at low temperatures and nonspontaneous at high temperatures. 
D) spontaneous at all temperatures. 
A) nonspontaneous at all temperatures. 
B) nonspontaneous at low temperatures and spontaneous at high temperatures. 
C) spontaneous at low temperatures and nonspontaneous at high temperatures. 
D) spontaneous at all temperatures. B

Question 3

Imagine a reaction that results in a change in both volume and temperature,as shown in the diagram below.What is the sign of the work being done and the sign of the enthalpy change involved in this reaction?

Accepted Answer

A) w = + and ΔH = + 
B) w = + and ΔH = - 
C) w = - and ΔH = + 
D) w = - and ΔH = - 
A) w = + and ΔH = + 
B) w = + and ΔH = - 
C) w = - and ΔH = + 
D) w = - and ΔH = - A

Question 4

Given that ΔH°= -311 kJ for the hydrogenation of acetylene,C2H2: H-C   C-H(g)+ 2 H2(g)→ CH3-CH3(g)
And the following bond dissociation energies,estimate a value for the C-to-C triple bond dissociation energy.

Accepted Answer

A) 1050 kJ/mol 
B) 833 kJ/mol 
C) 807 kJ/mol 
D) 397 kJ/mol 
A) 1050 kJ/mol 
B) 833 kJ/mol 
C) 807 kJ/mol 
D) 397 kJ/mol

Question 5

For the conversion of water to ice at 25°C and 1 atm,

Accepted Answer

A) ΔG is negative and ΔH is negative. 
B) ΔG is negative and ΔH is positive. 
C) ΔG is positive and ΔH is negative. 
D) ΔG is positive and ΔH is positive. 
A) ΔG is negative and ΔH is negative. 
B) ΔG is negative and ΔH is positive. 
C) ΔG is positive and ΔH is negative. 
D) ΔG is positive and ΔH is positive.

Question 6

Methanol can be produced from carbon monoxide and hydrogen with suitable catalysts: CO(g)+ 2 H2(g)→ CH3OH(l)at 25°C ΔH° = -128.1 kJ and ΔS° = -332 J/K
Find ΔG° at 25°C.

Accepted Answer

A) -157.2 kJ 
B) -29.1 kJ 
C) 98.9 kJ 
D) 157.2 kJ 
A) -157.2 kJ 
B) -29.1 kJ 
C) 98.9 kJ 
D) 157.2 kJ

Question 7

The sign of ΔG for a reaction is ________ if the reaction is spontaneous,________ if the reaction is at equilibrium,and ________ if the reaction is nonspontaneous.

Accepted Answer

negative,z

Question 8

Find ΔE° for the reaction below if the process is carried out at a constant pressure of 1.00 atm and ΔV (the volume change)= -24.5 L.(1 L ∙ atm = 101 J) 2 CO(g)+ O2 (g)→ 2 CO2(g)ΔH° = -566.kJ

Accepted Answer

A) +2.47 kJ 
B) -2.47 kJ 
C) -564 kJ 
D) -568 kJ 
A) +2.47 kJ 
B) -2.47 kJ 
C) -564 kJ 
D) -568 kJ

Question 9

The heat of vaporization of water at 100°C is 40.66 kJ/mol.Calculate the quantity of heat that is absorbed/released when 7.00 g of steam condenses to liquid water at 100°C.

Accepted Answer

A) 15.8 kJ of heat are absorbed. 
B) 15.8 kJ of heat are released. 
C) 105 kJ of heat are absorbed. 
D) 105 kJ of heat are released. 
A) 15.8 kJ of heat are absorbed. 
B) 15.8 kJ of heat are released. 
C) 105 kJ of heat are absorbed. 
D) 105 kJ of heat are released.

Question 10

An ideal gas expands into a vacuum (external pressure = 0)without gaining or losing heat.For this expansion

Accepted Answer

A) ΔE increases. 
B) ΔE does not change. 
C) ΔE decreases. 
D) ΔE = TΔS. 
A) ΔE increases. 
B) ΔE does not change. 
C) ΔE decreases. 
D) ΔE = TΔS.

Question 11

When 20.00 moles of H2(g)reacts with 10.00 mol of O2(g)to form 20.00 mol of H2O(l)at 25°C and a constant pressure of 1.00 atm.If 1366 kJ of heat are released during this reaction,and PΔV is equal to -74.00 kJ,then

Accepted Answer

A) ΔH° = +1366 kJ and ΔE° = +1440 kJ. 
B) ΔH° = +1366 kJ and ΔE° = +1292 kJ. 
C) ΔH° = -1366 kJ and ΔE° = -1292 kJ. 
D) ΔH° = -1366 kJ and ΔE° = -1440 kJ. 
A) ΔH° = +1366 kJ and ΔE° = +1440 kJ. 
B) ΔH° = +1366 kJ and ΔE° = +1292 kJ. 
C) ΔH° = -1366 kJ and ΔE° = -1292 kJ. 
D) ΔH° = -1366 kJ and ΔE° = -1440 kJ.

Question 12

Heat of formation for CO is -110.5 KJ/mol and the heat of formation for MgO is -602 KJ/mol.Which of the following statements is true?

Accepted Answer

A) The bond in CO is stronger than the bond in MgO. 
B) The bond in MgO is stronger than the bond in CO. 
C) The bonds in MgO and CO are equally strong. 
D) Impossible to determine to given data. 
A) The bond in CO is stronger than the bond in MgO. 
B) The bond in MgO is stronger than the bond in CO. 
C) The bonds in MgO and CO are equally strong. 
D) Impossible to determine to given data.

Question 13

When 50.0 mL of 0.400 M Ca(NO3)2 is added to 50.0 mL of 0.800 M NaF,CaF2 precipitates,as shown in the net ionic equation below.The initial temperature of both solutions is 30.00°C.Assuming that the reaction goes to completion,and that the resulting solution has a mass of 100.00 g and a specific heat of 4.18 J/(g ∙ °C),calculate the final temperature of the solution. Ca2+(aq)+ 2 F-(aq)→ CaF2(s)ΔH° = -11.5 kJ

Accepted Answer

A) 29.45°C 
B) 30.55°C 
C) 31.10°C 
D) 31.65°C 
A) 29.45°C 
B) 30.55°C 
C) 31.10°C 
D) 31.65°C

Question 14

Which combination always results in a reaction being spontaneous?

Accepted Answer

A) ΔH is negative and ΔS is negative. 
B) ΔH is negative and ΔS is positive. 
C) ΔH is positive and ΔS is negative. 
D) ΔH is positive and ΔS is positive. 
A) ΔH is negative and ΔS is negative. 
B) ΔH is negative and ΔS is positive. 
C) ΔH is positive and ΔS is negative. 
D) ΔH is positive and ΔS is positive.

Question 15

In which case is the work done on the system always positive?

Accepted Answer

A) ΔE > 0 B) ΔV > 0 C) ΔV = 0 D) ΔV < 0 A) ΔE > 0 B) ΔV > 0 C) ΔV = 0 D) ΔV < 0

Question 16

The specific heat of copper is 0.385 J/(g ∙ °C).If 34.2 g of copper,initially at 25°C,absorbs 7.880 kJ,what will be the final temperature of the copper?

Accepted Answer

A) 25.4°C 
B) 27.8°C 
C) 598°C 
D) 623°C 
A) 25.4°C 
B) 27.8°C 
C) 598°C 
D) 623°C

Question 17

It takes 11.2 kJ of energy to raise the temperature of 145 g of benzene from 22.0°C to 67.0°C.What is the specific heat of benzene?

Accepted Answer

A) 1.15 J/(g ∙ °
C)  
B) 1.72 J/(g ∙ °
C)  
C) 3.48 J/(g ∙ °
C)  
D) 5.18 J/(g ∙ °
C)  
A) 1.15 J/(g ∙ °
C)  
B) 1.72 J/(g ∙ °
C)  
C) 3.48 J/(g ∙ °
C)  
D) 5.18 J/(g ∙ °
C)

Question 18

The following drawing is a representation of a reaction of the type A → B,where different shaded spheres represent different molecular structures.For this reaction ΔH° = +45 kJ.This reaction is likely to be

Accepted Answer

A) nonspontaneous at all temperatures. 
B) nonspontaneous at low temperatures and spontaneous at high temperatures. 
C) spontaneous at low temperatures and nonspontaneous at high temperatures. 
D) spontaneous at all temperatures. 
A) nonspontaneous at all temperatures. 
B) nonspontaneous at low temperatures and spontaneous at high temperatures. 
C) spontaneous at low temperatures and nonspontaneous at high temperatures. 
D) spontaneous at all temperatures.

Question 19

10.0 g of a metal,initially at 25°C,are placed into 10.0 g of water,initially at 100°C.Which metal will have the highest final temperature? Shown after each metal is its specific heat in J/(g∙°C).

Accepted Answer

A) sodium (1.23) 
B) calcium (0.650) 
C) lead (0.160) 
D) nickel (0.440) 
A) sodium (1.23) 
B) calcium (0.650) 
C) lead (0.160) 
D) nickel (0.440)

Question 20

When 6.000 moles of H2(g)reacts with 3.000 mol of O2(g)to form 6.000 mol of H2O(l)at 25°C and a constant pressure of 1.00 atm.If 409.8 kJ of heat are released during this reaction,and PΔV is equal to -22.20 kJ,then

Accepted Answer

A) ΔH° = +409.8 kJ and ΔE° = +432.0 kJ. 
B) ΔH° = +409.8 kJ and ΔE° = +387.6 kJ. 
C) ΔH° = -409.8 kJ and ΔE° = -387.6 kJ. 
D) ΔH° = -409.8 kJ and ΔE° = -432.0 kJ. 
A) ΔH° = +409.8 kJ and ΔE° = +432.0 kJ. 
B) ΔH° = +409.8 kJ and ΔE° = +387.6 kJ. 
C) ΔH° = -409.8 kJ and ΔE° = -387.6 kJ. 
D) ΔH° = -409.8 kJ and ΔE° = -432.0 kJ.

Exam 9: Thermochemistry: Chemical Energy

If a reaction with a negative value of ΔS is nonspontaneous at constant temperature and pressure,

The following drawing is a representation of a reaction for which ΔH° = +62 kJ.This reaction is likely to be

Imagine a reaction that results in a change in both volume and temperature,as shown in the diagram below.What is the sign of the work being done and the sign of the enthalpy change involved in this reaction?

Given that ΔH°= -311 kJ for the hydrogenation of acetylene,C2H2: H-C C-H(g)+ 2 H2(g)→ CH3-CH3(g) And the following bond dissociation energies,estimate a value for the C-to-C triple bond dissociation energy.

For the conversion of water to ice at 25°C and 1 atm,

Methanol can be produced from carbon monoxide and hydrogen with suitable catalysts: CO(g)+ 2 H2(g)→ CH3OH(l)at 25°C ΔH° = -128.1 kJ and ΔS° = -332 J/K Find ΔG° at 25°C.

The sign of ΔG for a reaction is ________ if the reaction is spontaneous,________ if the reaction is at equilibrium,and ________ if the reaction is nonspontaneous.

Find ΔE° for the reaction below if the process is carried out at a constant pressure of 1.00 atm and ΔV (the volume change)= -24.5 L.(1 L ∙ atm = 101 J) 2 CO(g)+ O2 (g)→ 2 CO2(g)ΔH° = -566.kJ

The heat of vaporization of water at 100°C is 40.66 kJ/mol.Calculate the quantity of heat that is absorbed/released when 7.00 g of steam condenses to liquid water at 100°C.

An ideal gas expands into a vacuum (external pressure = 0)without gaining or losing heat.For this expansion

When 20.00 moles of H2(g)reacts with 10.00 mol of O2(g)to form 20.00 mol of H2O(l)at 25°C and a constant pressure of 1.00 atm.If 1366 kJ of heat are released during this reaction,and PΔV is equal to -74.00 kJ,then

Heat of formation for CO is -110.5 KJ/mol and the heat of formation for MgO is -602 KJ/mol.Which of the following statements is true?

Which combination always results in a reaction being spontaneous?

In which case is the work done on the system always positive?

The specific heat of copper is 0.385 J/(g ∙ °C).If 34.2 g of copper,initially at 25°C,absorbs 7.880 kJ,what will be the final temperature of the copper?

It takes 11.2 kJ of energy to raise the temperature of 145 g of benzene from 22.0°C to 67.0°C.What is the specific heat of benzene?

The following drawing is a representation of a reaction of the type A → B,where different shaded spheres represent different molecular structures.For this reaction ΔH° = +45 kJ.This reaction is likely to be

10.0 g of a metal,initially at 25°C,are placed into 10.0 g of water,initially at 100°C.Which metal will have the highest final temperature? Shown after each metal is its specific heat in J/(g∙°C).

When 6.000 moles of H2(g)reacts with 3.000 mol of O2(g)to form 6.000 mol of H2O(l)at 25°C and a constant pressure of 1.00 atm.If 409.8 kJ of heat are released during this reaction,and PΔV is equal to -22.20 kJ,then

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Given that ΔH°= -311 kJ for the hydrogenation of acetylene,C₂H₂: H-C C-H(g)+ 2 H₂(g)→ CH₃-CH₃(g) And the following bond dissociation energies,estimate a value for the C-to-C triple bond dissociation energy.

Methanol can be produced from carbon monoxide and hydrogen with suitable catalysts: CO(g)+ 2 H₂(g)→ CH₃OH(l)at 25°C ΔH° = -128.1 kJ and ΔS° = -332 J/K Find ΔG° at 25°C.

The sign of ΔG for a reaction is if the reaction is spontaneous, if the reaction is at equilibrium,and if the reaction is nonspontaneous.

Find ΔE° for the reaction below if the process is carried out at a constant pressure of 1.00 atm and ΔV (the volume change)= -24.5 L.(1 L ∙ atm = 101 J) 2 CO(g)+ O₂ (g)→ 2 CO₂(g)ΔH° = -566.kJ

When 20.00 moles of H₂(g)reacts with 10.00 mol of O₂(g)to form 20.00 mol of H₂O(l)at 25°C and a constant pressure of 1.00 atm.If 1366 kJ of heat are released during this reaction,and PΔV is equal to -74.00 kJ,then

When 6.000 moles of H₂(g)reacts with 3.000 mol of O₂(g)to form 6.000 mol of H₂O(l)at 25°C and a constant pressure of 1.00 atm.If 409.8 kJ of heat are released during this reaction,and PΔV is equal to -22.20 kJ,then