Chapter 4-Chemical Dominoes
Section 1: Energy and Entropy: Alternative Reaction Pathways
Pre-Test
1) In a cup of liquid water, when would the water molecules stop moving?
a. The molecules would stop moving if the liquid water in the cup became a solid.
b. The molecules would stop moving if the liquid water in the cup became a gas.
c. The molecules would stop moving if the liquid water in the cup became still.
d. The molecules would not stop in the cup of liquid water.
2) In which state of matter are the molecules spaced farthest apart?
a. A gas
b. A liquid
c. A solid
d. All are equal
3) Which of the following always results from a chemical reaction?
a. Fire
b. Bubbles
c. A new substance that is a solid
d. A new substance that can be a solid, liquid, or gas
4) How do the molecules of hot air differ from the molecules of cold air?
a. The molecules of hot air have less entropy and enthalpy than the molecules of cold
air.
b. The molecules of hot air have more entropy and more enthalpy than the molecules of
cold air.
c. The molecules of hot air have more heat molecules mixed with them.
d. The molecules of hot air are smaller than the molecules of cold air.
5) In the morning, a student puts a warm can of soda in a cooler filled with ice.
He closes the cooler (which is now the system). At lunch, the can of soda is colder. What
happened to the total amount of energy in the system containing the can of soda and the
ice? (Assume that no energy is transferred from the system to the surroundings when
cooler is closed.)
a. The total amount of energy in the system increased because the energy that the can of
soda transferred to the ice is greater than the energy that the ice lost.
b. The total amount of energy in the system decreased because the can of soda has less
energy than it started with, and the amount of energy the ice has did not change.
c. The total amount of energy in the system stayed the same because the amount of
energy that the can of soda lost is equal to the amount of energy that the ice gained.
d. The total amount of energy in the system stayed the same because being warmer or
colder does not affect the amount of energy objects have.
Pre-Test Answer Key
1)
2)
3)
4)
5)
D
A
D
B
C