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Mastering Chemistry – Ch. 5

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Jul 10th, 2023
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47 test answers
question
Calculate the standard enthalpy change for the reaction2A+B⇌2C+2D
answer
ΔHrxn∘ =279 kJ
question
For the reaction given in Part A, how much heat is absorbed when 3.80 mol of A reacts?
answer
530 kJ
question
How much heat is needed to raise the temperature of a 5.0 gram block of aluminum from 22.0° C to 37.0° C?
answer
68 J
question
Combustion reactions are most conveniently studied _____.
answer
using constant-volume calorimetry
question
The specific heat of silver (Ag) is 0.245 J/ºC g. Determine the energy required to raise the temperature of 350. g of Ag from 293 K to 400 K.
answer
9.17 kJ
question
A total of 2.00 mol of a compound is allowed to react with water in a foam coffee cup and the reaction produces 173 g of solution. The reaction caused the temperature of the solution to rise from 21.00 to 24.70 ∘C. What is the enthalpy of this reaction? Assume that no heat is lost to the surroundings or to the coffee cup itself and that the specific heat of the solution is the same as that of pure water.
answer
ΔH=-1.34kJ/mol
question
Which substance in the table undergoes the greatest temperature change when the same mass of each substance absorbs the same quantity of heat?
answer
Hg(l)
question
Is the process shown in the figure endothermic or exothermic?
answer
endothermic
question
It takes 54.0 J to raise the temperature of an 10.7 g piece of unknown metal from 13.0∘C to 24.3 ∘C. What is the specific heat for the metal?
answer
Cs=0.447 J⋅(g⋅∘C)−1
question
The molar heat capacity of silver is 25.35 J/mol⋅∘C. How much energy would it take to raise the temperature of 10.7 g of silver by 12.1 ∘C?
answer
q =30.4 J
question
What is the specific heat of silver?
answer
0.235 J⋅(g⋅∘C)−1
question
What are the units of molar heat capacity?
answer
J/mol−KJ or J/mol−∘C
question
What are the units of specific heat?
answer
J/g−K or J/g−∘C.
question
If you know the specific heat of copper, what additional information do you need to calculate the heat capacity of a particular piece of copper pipe?
answer
mass of the piece
question
A 100.0-g bar of gold is heated from 25 ∘C to 50 ∘C, during which it absorbs 322 J of heat. Assume the volume of the gold bar remains constant.Based on the data, calculate the specific heat of Au(s).
answer
0.13 J/g ∘C
question
Suppose that the same amount of heat is added to two 10.0-g blocks of metal, both initially at the same temperature. One block is gold metal, and one is iron metal. Which block will have the greater rise in temperature after the addition of the heat? (Note that the specific heat of iron is 0.451 J/g⋅∘C.)
answer
The gold block will have the higher final temperature.
question
What is the molar heat capacity of Au(s)?
answer
25 J⋅(mol⋅∘C)−1
question
Calculate ΔH (in kJ/mol NaOH) for the solution process NaOH(s)→Na+(aq)+OH−(aq)Assume that the specific heat of the solution is the same as that of pure water.
answer
-44.4 kJ/mol
question
Calculate ΔH (in kJ/mol NH4NO3) for the solution processNH4NO3(s)→NH+4(aq)+NO−3(aq)Assume that the specific heat of the solution is the same as that of pure water.
answer
26 kJ/mol
question
Is this process endothermic or exothermic?
answer
endothermic
question
A volume of 110. mL of H2O is initially at room temperature (22.00 ∘C). A chilled steel rod at 2.00 ∘C is placed in the water. If the final temperature of the system is 21.20 ∘C , what is the mass of the steel bar?Use the following values:specific heat of water = 4.18 J/(g⋅∘C) specific heat of steel = 0.452 J/(g⋅∘C)
answer
mass of the steel =42.4 g
question
The specific heat of water is 4.18 J/(g⋅∘C). Calculate the molar heat capacity of water.
answer
molar heat capacity for water=75.2 J/mol⋅∘C
question
A calorimeter contains 31.0 mL of water at 15.0 ∘C . When 2.00 g of X (a substance with a molar mass of 53.0 g/mol ) is added, it dissolves via the reactionX(s)+H2O(l)→X(aq)and the temperature of the solution increases to 26.5 ∘C .Calculate the enthalpy change, ΔH, for this reaction per mole of X.Assume that the specific heat of the resulting solution is equal to that of water [4.18 J/(g⋅∘C)], that density of water is 1.00 g/mL, and that no heat is lost to the calorimeter itself, nor to the surroundings.
answer
ΔH=-42.0kJ/mol
question
Consider the reactionC12H22O11(s)+12O2(g)→12CO2(g)+11H2O(l)in which 10.0 g of sucrose, C12H22O11, was burned in a bomb calorimeter with a heat capacity of 7.50 kJ/∘C. The temperature increase inside the calorimeter was found to be 22.0 ∘C. Calculate the change in internal energy, ΔE, for this reaction per mole of sucrose.
answer
Δ =-5650kJ/mol
question
Calculate the enthalpy of the reaction2NO(g)+O2(g)→2NO2(g)given the following reactions and enthalpies of formation:
answer
ΔH∘ =-114.0 kJ
question
Calculate the enthalpy of the reaction4B(s)+3O2(g)→2B2O3(s)given the following pertinent information:
answer
ΔH∘ =-2552 kJ
question
The overall enthalpy change for a reaction _____.
answer
depends only on the amount of matter that undergoes the change and on the initial state of the reactants and the final state of the products
question
Calculate ΔH for the reaction:NO (g) + O (g) → NO2 (g)given the following information:
answer
-304.1 kJ
question
Enthalpy diagram for combustion of 1 mol of methane. The enthalpy change of the one-step reaction equals the sum of the enthalpy changes of the reaction run in two steps: -890 kJ = -802 kJ+ (-88 kJ).What process corresponds to the -88 kJ enthalpy change?
answer
The condensation of 2 H2O(g) to 2 H2O(l).
question
Consider the following hypothetical reactions:A→BΔH=+24kJB→CΔH=+62kJUse Hess's law to calculate the enthalpy change for the reaction A→C.
answer
ΔH =86kJ
question
Calculate the enthalpy change for the reactionP4O6(s)+2O2(g)→P4O10(s)given the following enthalpies of reaction:P4(s)+3O2(g)→P4O6(s)ΔH=−1640.1kJP4(s)+5O2(g)→P4O10(s)ΔH=−2940.1kJ
answer
ΔHrxn∘=-1300kJ
question
From the enthalpies of reaction calculate ΔH for the reactionCO(g)+2H2(g) → CH3OH(g)
answer
-90.7 kJ
question
From the enthalpies of reaction calculate ΔH for the reaction of ethylene withF2:C2H4(g)+6F2(g)→2CF4(g)+4HF(g)
answer
ΔHrxn=-2490kJ
question
Given the following data:use Hess's law to calculate ΔH for the following reaction:N2O(g)+NO2(g)→3NO(g)
answer
ΔH =155.7kJ
question
The equations given in the problem introduction can be added together to give the following reaction:overall: C + 1/2O2→COHowever, one of them must be reversed. Which one?
answer
CO+12O2→CO2
question
What is the enthalpy for reaction 1 reversed?reaction 1 reversed: CO2→CO + 1/2O2
answer
ΔH =283kJ/mol
question
What is the enthalpy for the following reaction?overall: C + 1/2O2→CO
answer
ΔH=-110kJ/mol
question
ΔH f° _____.
answer
is usually reported at 298K
question
Given:C2H4(g)+3O2(g)↔2CO2(g)+2H2O(g)ΔHf(C2H4)=52.5kJ/molΔHf(H2O)=-285.8 kJ/molΔ H0rxn=-1411.1 kJ/mol.Find ΔHf(CO2)=.
answer
-393.5 kJ/mol
question
For which of the following reactions is ΔHrxn∘ equal to ΔHf∘ of the product(s)?You do not need to look up any values to answer this question.
answer
Li(s)+12F2(g)→LiF(s)S(s)+O2(g)→SO2(g)
question
The combustion of propane, C3H8C3H8, occurs via the reactionC3H8(g)+5O2(g)→3CO2(g)+4H2O(g)with heat of formation values given by the following table:SubstanceΔH∘fΔHf∘(kJ/mol)C3H8C3H8(g)-104.7CO2(g)−393.5H2O(g)−−241.8
answer
ΔHrxn∘=-2043 kJ
question
Write a balanced chemical equation for the reaction depicted.
answer
O2(g)+N2(g)→2NO(g)
question
Predict whether w is positive, negative, or zero.
answer
zero
question
Using data from Appendix C in the textbook, determine ΔH for the formation of one mole of the product.
answer
ΔH =90.4kJ
question
Choose the enthalpy diagram for the reaction. (Asume the bold arrow shows the reaction as written; combination of the two thin arrows shows an alternate route from A to B).
answer
Two arrows up to B, one arrow down from A
question
Suppose the overall reaction is endothermic. What can you conclude?
answer
ΔH∘f(A)<ΔH∘f(B)
question
What is ΔH∘rxnΔHrxn∘ for the following chemical reaction?CO(g)+NH3(g)→HCN(g)+H2O(g)You can use the following table of standard heats of formation (ΔH∘f)(ΔHf∘) to calculate the enthalpy of the given reaction.
answer
45.1 kJ
1 of 47
question
Calculate the standard enthalpy change for the reaction2A+B⇌2C+2D
answer
ΔHrxn∘ =279 kJ
question
For the reaction given in Part A, how much heat is absorbed when 3.80 mol of A reacts?
answer
530 kJ
question
How much heat is needed to raise the temperature of a 5.0 gram block of aluminum from 22.0° C to 37.0° C?
answer
68 J
question
Combustion reactions are most conveniently studied _____.
answer
using constant-volume calorimetry
question
The specific heat of silver (Ag) is 0.245 J/ºC g. Determine the energy required to raise the temperature of 350. g of Ag from 293 K to 400 K.
answer
9.17 kJ
question
A total of 2.00 mol of a compound is allowed to react with water in a foam coffee cup and the reaction produces 173 g of solution. The reaction caused the temperature of the solution to rise from 21.00 to 24.70 ∘C. What is the enthalpy of this reaction? Assume that no heat is lost to the surroundings or to the coffee cup itself and that the specific heat of the solution is the same as that of pure water.
answer
ΔH=-1.34kJ/mol
question
Which substance in the table undergoes the greatest temperature change when the same mass of each substance absorbs the same quantity of heat?
answer
Hg(l)
question
Is the process shown in the figure endothermic or exothermic?
answer
endothermic
question
It takes 54.0 J to raise the temperature of an 10.7 g piece of unknown metal from 13.0∘C to 24.3 ∘C. What is the specific heat for the metal?
answer
Cs=0.447 J⋅(g⋅∘C)−1
question
The molar heat capacity of silver is 25.35 J/mol⋅∘C. How much energy would it take to raise the temperature of 10.7 g of silver by 12.1 ∘C?
answer
q =30.4 J
question
What is the specific heat of silver?
answer
0.235 J⋅(g⋅∘C)−1
question
What are the units of molar heat capacity?
answer
J/mol−KJ or J/mol−∘C
question
What are the units of specific heat?
answer
J/g−K or J/g−∘C.
question
If you know the specific heat of copper, what additional information do you need to calculate the heat capacity of a particular piece of copper pipe?
answer
mass of the piece
question
A 100.0-g bar of gold is heated from 25 ∘C to 50 ∘C, during which it absorbs 322 J of heat. Assume the volume of the gold bar remains constant.Based on the data, calculate the specific heat of Au(s).
answer
0.13 J/g ∘C
question
Suppose that the same amount of heat is added to two 10.0-g blocks of metal, both initially at the same temperature. One block is gold metal, and one is iron metal. Which block will have the greater rise in temperature after the addition of the heat? (Note that the specific heat of iron is 0.451 J/g⋅∘C.)
answer
The gold block will have the higher final temperature.
question
What is the molar heat capacity of Au(s)?
answer
25 J⋅(mol⋅∘C)−1
question
Calculate ΔH (in kJ/mol NaOH) for the solution process NaOH(s)→Na+(aq)+OH−(aq)Assume that the specific heat of the solution is the same as that of pure water.
answer
-44.4 kJ/mol
question
Calculate ΔH (in kJ/mol NH4NO3) for the solution processNH4NO3(s)→NH+4(aq)+NO−3(aq)Assume that the specific heat of the solution is the same as that of pure water.
answer
26 kJ/mol
question
Is this process endothermic or exothermic?
answer
endothermic
question
A volume of 110. mL of H2O is initially at room temperature (22.00 ∘C). A chilled steel rod at 2.00 ∘C is placed in the water. If the final temperature of the system is 21.20 ∘C , what is the mass of the steel bar?Use the following values:specific heat of water = 4.18 J/(g⋅∘C) specific heat of steel = 0.452 J/(g⋅∘C)
answer
mass of the steel =42.4 g
question
The specific heat of water is 4.18 J/(g⋅∘C). Calculate the molar heat capacity of water.
answer
molar heat capacity for water=75.2 J/mol⋅∘C
question
A calorimeter contains 31.0 mL of water at 15.0 ∘C . When 2.00 g of X (a substance with a molar mass of 53.0 g/mol ) is added, it dissolves via the reactionX(s)+H2O(l)→X(aq)and the temperature of the solution increases to 26.5 ∘C .Calculate the enthalpy change, ΔH, for this reaction per mole of X.Assume that the specific heat of the resulting solution is equal to that of water [4.18 J/(g⋅∘C)], that density of water is 1.00 g/mL, and that no heat is lost to the calorimeter itself, nor to the surroundings.
answer
ΔH=-42.0kJ/mol
question
Consider the reactionC12H22O11(s)+12O2(g)→12CO2(g)+11H2O(l)in which 10.0 g of sucrose, C12H22O11, was burned in a bomb calorimeter with a heat capacity of 7.50 kJ/∘C. The temperature increase inside the calorimeter was found to be 22.0 ∘C. Calculate the change in internal energy, ΔE, for this reaction per mole of sucrose.
answer
Δ =-5650kJ/mol
question
Calculate the enthalpy of the reaction2NO(g)+O2(g)→2NO2(g)given the following reactions and enthalpies of formation:
answer
ΔH∘ =-114.0 kJ
question
Calculate the enthalpy of the reaction4B(s)+3O2(g)→2B2O3(s)given the following pertinent information:
answer
ΔH∘ =-2552 kJ
question
The overall enthalpy change for a reaction _____.
answer
depends only on the amount of matter that undergoes the change and on the initial state of the reactants and the final state of the products
question
Calculate ΔH for the reaction:NO (g) + O (g) → NO2 (g)given the following information:
answer
-304.1 kJ
question
Enthalpy diagram for combustion of 1 mol of methane. The enthalpy change of the one-step reaction equals the sum of the enthalpy changes of the reaction run in two steps: -890 kJ = -802 kJ+ (-88 kJ).What process corresponds to the -88 kJ enthalpy change?
answer
The condensation of 2 H2O(g) to 2 H2O(l).
question
Consider the following hypothetical reactions:A→BΔH=+24kJB→CΔH=+62kJUse Hess's law to calculate the enthalpy change for the reaction A→C.
answer
ΔH =86kJ
question
Calculate the enthalpy change for the reactionP4O6(s)+2O2(g)→P4O10(s)given the following enthalpies of reaction:P4(s)+3O2(g)→P4O6(s)ΔH=−1640.1kJP4(s)+5O2(g)→P4O10(s)ΔH=−2940.1kJ
answer
ΔHrxn∘=-1300kJ
question
From the enthalpies of reaction calculate ΔH for the reactionCO(g)+2H2(g) → CH3OH(g)
answer
-90.7 kJ
question
From the enthalpies of reaction calculate ΔH for the reaction of ethylene withF2:C2H4(g)+6F2(g)→2CF4(g)+4HF(g)
answer
ΔHrxn=-2490kJ
question
Given the following data:use Hess's law to calculate ΔH for the following reaction:N2O(g)+NO2(g)→3NO(g)
answer
ΔH =155.7kJ
question
The equations given in the problem introduction can be added together to give the following reaction:overall: C + 1/2O2→COHowever, one of them must be reversed. Which one?
answer
CO+12O2→CO2
question
What is the enthalpy for reaction 1 reversed?reaction 1 reversed: CO2→CO + 1/2O2
answer
ΔH =283kJ/mol
question
What is the enthalpy for the following reaction?overall: C + 1/2O2→CO
answer
ΔH=-110kJ/mol
question
ΔH f° _____.
answer
is usually reported at 298K
question
Given:C2H4(g)+3O2(g)↔2CO2(g)+2H2O(g)ΔHf(C2H4)=52.5kJ/molΔHf(H2O)=-285.8 kJ/molΔ H0rxn=-1411.1 kJ/mol.Find ΔHf(CO2)=.
answer
-393.5 kJ/mol
question
For which of the following reactions is ΔHrxn∘ equal to ΔHf∘ of the product(s)?You do not need to look up any values to answer this question.
answer
Li(s)+12F2(g)→LiF(s)S(s)+O2(g)→SO2(g)
question
The combustion of propane, C3H8C3H8, occurs via the reactionC3H8(g)+5O2(g)→3CO2(g)+4H2O(g)with heat of formation values given by the following table:SubstanceΔH∘fΔHf∘(kJ/mol)C3H8C3H8(g)-104.7CO2(g)−393.5H2O(g)−−241.8
answer
ΔHrxn∘=-2043 kJ
question
Write a balanced chemical equation for the reaction depicted.
answer
O2(g)+N2(g)→2NO(g)
question
Predict whether w is positive, negative, or zero.
answer
zero
question
Using data from Appendix C in the textbook, determine ΔH for the formation of one mole of the product.
answer
ΔH =90.4kJ
question
Choose the enthalpy diagram for the reaction. (Asume the bold arrow shows the reaction as written; combination of the two thin arrows shows an alternate route from A to B).
answer
Two arrows up to B, one arrow down from A
question
Suppose the overall reaction is endothermic. What can you conclude?
answer
ΔH∘f(A)<ΔH∘f(B)
question
What is ΔH∘rxnΔHrxn∘ for the following chemical reaction?CO(g)+NH3(g)→HCN(g)+H2O(g)You can use the following table of standard heats of formation (ΔH∘f)(ΔHf∘) to calculate the enthalpy of the given reaction.
answer
45.1 kJ