Question 1

Which of the following processes always results in an increase in the energy of a system?

Accepted Answer

A) The system loses heat and does work on the surroundings. 
B) The system gains heat and does work on the surroundings. 
C) The system loses heat and has work done on it by the surroundings. 
D) The system gains heat and has work done on it by the surroundings. 
E) None of these is always true.

Question 2

At body temperature 2,404 joules of energy are required to evaporate 1.00 g of water.After vigorous exercise, a person feels chilly because the body is giving up heat to evaporate the perspiration.A typical person perspires 25 mL of water after 20.minutes of exercise.How much body heat is this person using to evaporate this water?

Accepted Answer

The answer of At body temperature 2,404 joules of energy...

Question 3

Ethanol (C2H5OH)burns according to the equation C2H5OH(l)+ 3O2(g)$\rarr$2CO2(g)+ 3H2O(l), $\Delta$H°rxn = -1367 kJ/mol.
How much heat is released when 35.0 g of ethanol is burned?

Accepted Answer

A) 1,797 kJ 
B) 1,367 kJ 
C) 9.61 * 10-4 kJ 
D) 4.78 * 104 kJ 
E) 1,040 kJ

Question 4

A piece of copper with a mass of 218 g has a heat capacity of 83.9 J/°C. What is the specific heat of copper?

Accepted Answer

A) 0.385 J/g·°C 
B) 1.83 * 104 J/g·°C 
C) 2.60 J/g·°C 
D) 1.32 J/g·°C 
E) 24.5 J/g·°C

Question 5

At 25°C, the standard enthalpy of formation of anhydrous sodium carbonate is -1130.9 kJ/mol, whereas the standard enthalpy of formation of sodium carbonate monohydrate is -1430.1 kJ/mol. Determine $\Delta$H° at 25°C for the reaction Na2CO3(s)+ H2O(l)$\rarr$Na2CO3·H2O(s).
(Given: $\Delta$H°f[H2O(l)] = -285.8 kJ/mol)

Accepted Answer

A) -13.4 kJ/mol 
B) -285.8 kJ/mol 
C) -585.0 kJ/mol 
D) -299.2 kJ/mol 
E) -156.3 kJ/mol

Question 6

At 25°C, the standard enthalpy of formation of KCl(s)is -435.87 kJ/mol. When one mole of KCl(s)is formed by reacting potassium vapor and chlorine gas at 25°C, the standard enthalpy of reaction is -525.86 kJ/mol. Find $\Delta$H° for the sublimation of potassium, K(s)$\rarr$K(g), at 25°C.

Accepted Answer

A) -345.88 kJ/mol 
B) 45.00 kJ/mol 
C) 345.88 kJ/mol 
D) 89.99 kJ/mol 
E) -525.86 kJ/mol

Question 7

What would be the standard enthalpy change for the reaction of one mole of H₂(g)with one mole of Cl₂(g)to produce two moles of HCl(g)at standard state conditions? [$\Delta$H°_f (HCl(g))= -92.3 kJ/mol]

Accepted Answer

The answer of What would be the standard enthalpy change...

Question 8

The enthalpy change when a strong acid is neutralized by strong base is -56.1 kJ/mol. If 12.0 mL of 6.00 M HBr at 21.30°C is mixed with 300.mL of 0.250 M NaOH, also at 21.30°C, what will the maximum temperature reached by the resulting solution? (Assume that there is no heat loss to the container, that the specific heat of the final solution is 4.18 J/g·°C, and that the density of the final solution is that of water.)

Accepted Answer

A) 18.20°C 
B) 24.53°C 
C) 101.8°C 
D) 24.40°C 
E) 34.25°C

Question 9

An endothermic reaction causes the surroundings to

Accepted Answer

A) warm up. 
B) become acidic. 
C) condense. 
D) decrease in temperature. 
E) release CO2.

Question 10

The heat of solution of calcium chloride CaCl₂ is -82.8 kJ/mol, and the combined heats of hydration of 1 mole of gaseous calcium ions and 2 mole of gaseous chloride ions is -2327 kJ.What is the lattice energy of calcium chloride?

Accepted Answer

The answer of The heat of solution of calcium chloride...

Question 11

The enthalpy of combustion of acetylene C₂H₂ is described by C₂H₂(g)+ (5/2)O₂(g)$\rarr$ 2CO₂(g)+ H₂O(l)$\Delta$H°_rxn= -1299 kJ/mol Calculate the enthalpy of formation of acetylene, given the following enthalpies of formation F1F1F1S1F1F1F10H°_f[CO₂(g)] = -393.5 kJ/mol F1F1F1S1F1F1F10H°_f[H₂O(l)] = -285.8 kJ/mol

Accepted Answer

The answer of The enthalpy of combustion of acetylene C₂H₂...

Exam 6: Thermo-Chemistry

Which of the following processes always results in an increase in the energy of a system?

Ethanol (C₂H₅OH) burns according to the equation C₂H₅OH(l) + 3O₂(g) $\rarr$ 2CO₂(g) + 3H₂O(l) , $\Delta$ H°_rxn = -1367 kJ/mol. How much heat is released when 35.0 g of ethanol is burned?

A piece of copper with a mass of 218 g has a heat capacity of 83.9 J/°C. What is the specific heat of copper?

At 25°C, the standard enthalpy of formation of KCl(s) is -435.87 kJ/mol. When one mole of KCl(s) is formed by reacting potassium vapor and chlorine gas at 25°C, the standard enthalpy of reaction is -525.86 kJ/mol. Find $\Delta$ H° for the sublimation of potassium, K(s) $\rarr$ K(g) , at 25°C.

What would be the standard enthalpy change for the reaction of one mole of H₂(g)with one mole of Cl₂(g)to produce two moles of HCl(g)at standard state conditions? [ $\Delta$ H°_f (HCl(g))= -92.3 kJ/mol]

An endothermic reaction causes the surroundings to

The heat of solution of calcium chloride CaCl₂ is -82.8 kJ/mol, and the combined heats of hydration of 1 mole of gaseous calcium ions and 2 mole of gaseous chloride ions is -2327 kJ.What is the lattice energy of calcium chloride?

Exam 6: Thermo-Chemistry

Which of the following processes always results in an increase in the energy of a system?

Ethanol (C2H5OH) burns according to the equation C2H5OH(l) + 3O2(g) →\rarr→ 2CO2(g) + 3H2O(l) , Δ\DeltaΔ H°rxn = -1367 kJ/mol. How much heat is released when 35.0 g of ethanol is burned?

A piece of copper with a mass of 218 g has a heat capacity of 83.9 J/°C. What is the specific heat of copper?

What would be the standard enthalpy change for the reaction of one mole of H2(g)with one mole of Cl2(g)to produce two moles of HCl(g)at standard state conditions? [ Δ\DeltaΔ H°f (HCl(g))= -92.3 kJ/mol]

An endothermic reaction causes the surroundings to

The heat of solution of calcium chloride CaCl2 is -82.8 kJ/mol, and the combined heats of hydration of 1 mole of gaseous calcium ions and 2 mole of gaseous chloride ions is -2327 kJ.What is the lattice energy of calcium chloride?

The enthalpy of combustion of acetylene C2H2 is described by C2H2(g)+ (5/2)O2(g) →\rarr→ 2CO2(g)+ H2O(l) Δ\DeltaΔ H°rxn= -1299 kJ/mol Calculate the enthalpy of formation of acetylene, given the following enthalpies of formation H°f[CO2(g)] = -393.5 kJ/mol H°f[H2O(l)] = -285.8 kJ/mol

Ethanol (C₂H₅OH) burns according to the equation C₂H₅OH(l) + 3O₂(g) $\rarr$ 2CO₂(g) + 3H₂O(l) , $\Delta$ H°_rxn = -1367 kJ/mol. How much heat is released when 35.0 g of ethanol is burned?

What would be the standard enthalpy change for the reaction of one mole of H₂(g)with one mole of Cl₂(g)to produce two moles of HCl(g)at standard state conditions? [ $\Delta$ H°_f (HCl(g))= -92.3 kJ/mol]

The heat of solution of calcium chloride CaCl₂ is -82.8 kJ/mol, and the combined heats of hydration of 1 mole of gaseous calcium ions and 2 mole of gaseous chloride ions is -2327 kJ.What is the lattice energy of calcium chloride?