THERMOCHEMISTRY QUIZ Part I

1. The statement which best describes a chemical reaction in which energy released is ….
a. exothermic and has a negative ΔH.
b. exothermic and has a positive ΔH.
c. endothermic and has a negative ΔH.
d. endothermic and has a positive ΔH.
2. When a chemical reaction occurs in which the products are more stable than the reactants ....
a. the potential energy of the reactants is completely transferred to the products.
b. the potential energy of the products is greater than the potential energy of the eactants.
c. the total amount of kinetic and potential energy of the chemicals in the reaction increases.
d. some of the potential energy of the reactants is transformed into kinetic energy.
e. the total amount of kinetic and potential energy of the chemicals in the reaction decreases.
3. The statement which gives the correct relationship between the sign of the change in internal energy and the system is ….
a. the change in internal energy is negative if Efinal is greater than Einitial.
b. The change in internal energy is positive if energy flows out of the surroundings and into the system.
c. The change in internal energy is positive if Einitial is greater than Efinal.
d. The change in internal energy is negative if energy flows out of the surroundings and into the system.
e. The change in internal energy is positive if energy flows out of the system and into the surroundings.
4. Which phase change is exothermic?
a. H2O(s) --> H2O(l)
b. H2O(l) --> H2O(s)
c. H2O(s) --> H2O(g)
d. H2O(l) --> H2O(g)
5. Which phase change is endothermic?
a. gas --> solid
b. gas --> liquid
c. liquid --> solid
d. liquid --> gas
6. The heat required to change 1 gram of a liquid at its normal boiling point to a gas at the same temperature is called the heat of ....
a. vaporization
b. fusion
c. reaction
d. formation
7. Solid A at 80 C is immersed in liquid B at 60 C. Which statement correctly describes the energy changes between A and B?
a. A releases heat and B absorbs heat.
b. A absorbs heat and B releases heat.
c. Both A and B absorb heat.
d. Both A and B release heat.
8. When ammonium chloride crystals are dissolved in water, the temperature of the water decreases. What does this temperature change indicate about the dissolving of ammonium chloride in water?
a. It is an endothermic reaction because it absorbs heat.
b. It is an endothermic reaction because it releases heat.
c. It is an exothermic reaction because it absorbs heat.
d. It is an exothermic reaction because it releases heat.
9. For a chemical reaction carried out at … the change in internal energy can be attributed to ….
a. constant volume; heat transfer
b. constant pressure; work
c. constant volume; work
d. constant pressure; heat transfer
e. constant volume; work and heat transfer
10. In order to ensure that comparisons of changes in enthalpy for reactions can be made, measurements of changes in enthalpy must be made under the conditions of ….
a. 298 K, 1 atm pressure, 1 M concentration for ions, and specified physical states.
b. 273 K, 1 atm pressure, 1M concentration, and specified physical states.
c. 298 K, 1 atm pressure, and 1 M concentration.
d. 273 K, 1 atm pressure, and 1M concentration.
e. 0°C, 1 atm pressure, 1M concentration, and specified physical states.