Unit 7: Thermochemistry

11. What is the study of energy changes that accompany chemical reactions called?

a) Thermodynamics
b) Kinetics
c) Thermochemistry
d) Electrochemistry
Answer: c) Thermochemistry

12. What is the primary unit of energy used in thermochemistry?

a) Joule
b) Calorie
c) Watt
d) Electronvolt
Answer: a) Joule

13. What is the energy change that occurs at constant pressure called?

a) Enthalpy change
b) Entropy change
c) Free energy change
d) Internal energy change
Answer: a) Enthalpy change

14. Which of the following represents an endothermic process?

a) Combustion of gasoline
b) Freezing of water
c) Melting of ice
d) Condensation of steam
Answer: c) Melting of ice

15. In an exothermic reaction, the energy of the products is:

a) Greater than the energy of the reactants
b) Less than the energy of the reactants
c) Equal to the energy of the reactants
d) Independent of the reactants
Answer: b) Less than the energy of the reactants

16. Which law states that energy cannot be created or destroyed?

a) Law of conservation of mass
b) Law of conservation of energy
c) Law of definite proportions
d) Law of multiple proportions
Answer: b) Law of conservation of energy

17. What is the heat absorbed or released during a phase change at constant temperature called?

a) Specific heat
b) Heat capacity
c) Latent heat
d) Sensible heat
Answer: c) Latent heat

18. Which of the following has the highest specific heat capacity?

a) Water
b) Iron
c) Aluminum
d) Copper
Answer: a) Water

19. What is the standard enthalpy change of formation of an element in its standard state?

a) 0 kJ/mol
b) 25 kJ/mol
c) 100 kJ/mol
d) -100 kJ/mol
Answer: a) 0 kJ/mol

20. In a calorimetry experiment, what does the term “q” represent?

a) Mass
b) Temperature
c) Heat energy
d) Pressure
Answer: c) Heat energy