Chapter 15 (p. 516)
Section 1
1. What is energy?
Ability to do work, produce heat or cause change.
2. Differentiate between potential and kinetic energy.
potential energy – energy due to composition or position
kinetic energy – energy of motion
3. The law of conservation of energy states energy can be converted from one form to another
but is neither created nor destroyed. (energy of the universe is constant)
4. What is a calorie? energy required to raise 1 gram of water by 1oC
5. 1 calorie = __4.184_____ joules
6. What is the difference between a calorie and a Calorie?
A Calorie measures the energy of food and is = to 1000 calories.
7. What is specific heat? The heat required to raise 1 gram of a substance by 1oC.
Section 2
8. Draw and label a basic calorimeter and explain how it works.
(drawing should include: thermometer, stirrer, ignition terminals, water, insulation, sealed
reaction chamber)
A sample of a substance is massed and placed in the sealed reaction chamber. The ignition
terminals ignite the sample using electricity and the sample is burned. The heat from the
sample flows into the water which causes the water’s temperature to increase. The increase
in temperature is measured using the thermometer. The equation, qw = (m)( T)(Cw), can
then be used to calculate the heat given off from the sample which can be used to determine
the calories in the sample.
9.
What is thermochemistry? the study of heat changes that accompany chemical reactions and
changes in state.
10. Distinguish between a thermochemical system, surroundings and universe.
System includes the specific part of the universe that contains the reaction or process,
surroundings include everything outside of the system. Universe includes the system and the
surroundings.
11. What is the enthalpy of reaction? The change in enthalpy (heat) for a reaction.
Section 3
12. What is a thermochemical equation? Chemical equations that includes all states of matter
and energy changes.
13. Distinguish between the molar enthalpy of fusion and the molar enthalpy of vaporization.
fusion – heat required to melt 1 mole of a substance
vaporization – heat required to vaporize 1 mole of a substance
Section 4
14. What is Hess’s Law? If you can add two or more chemical equations to produce a final
equation, then the sum of the enthalpy changes for the individual reactions will equal the
energy change for the final reaction.
Section 5
15. What is the difference between entropy and free energy? Free energy is the energy that is
available to do work. Energy associated with entropy is disordered and unable to do work.
16. The second law of thermodynamics states that spontaneous processes always proceed in such a
way that the entropy of the universe increases.