Matter and Energy Key
1. a. Heat energy is energy that flows between matter of different temperatures.
b. Heat energy flows from warmer substances to cooler substances.
c. units of measurement for heat energy: Joules and calories
2. Energy conversions with correct significant figures
a. 1,860 J
b. 1,800 mJ
c. 3,560 J
d. 10 cal
3. a. Endothermic
b. Exothermic
c. Endothermic
d. Endothermic
4. a. Temperature measures the heat energy abosrbed or released by particles that affects their speed of
motion.
b. degrees Celsius, most common; Kelvin for matter that exhibts extreme temperatures.
5. Temperature Conversions:
a. 273.0 K
b. 177 oC
c. 0 K
d. -48 0C
Phase Changes
1. no, stays constant during melting because heat energy is being utilized to weaken intermolecular forces
2. yes, heat energy is required for each phase change for the purpose of weakening intermoelcuar forces
(solid--> liquid--> gas) or strengthening intermolecular forces (gas--> liquid-->solid).
3. Yes, at 100oC
4. During condensation the only thing that changes is heat energy, it is released during condensation.
Temperature is constant.
5. As heat energy increases or is absorbed by the system the arrangement of particles becomes less
organized and the distance between the particles increases.
6. a. Rule between phase change and temp.: As phase changes occur temp. is always constant because the
heat energy being released or absorbed alters only the strength of the intermolecular forces.
b. Rule between phase change and temp.: As phase changes occur heat energy also changes. Heat
energy increases or is absorbed by system when melting, evaporation, and sublimation occurs. Heat energy
decreases or is released by the system when condensation, freezing, or deposition occurs.
7. Kinetic Molecular Theory connections:
a.
States of Matter
Intermolecular Forces
Heat Energy
Endo vs. Exo
Water freezing
increases
released
Exothermic
Water boiling
decreases
absorbed
Endothermic
Condensation of water vapor
increases
released
Exothermic
Sublimation of dry ice
decreases
absorbed
Endothermic
Deposition of copper on a penny
increases
releasesed
Exothermic
b. Using the table above one can establish a relationship between states of matter, intermolecular forces,
and heat energy which is what the Molecular Kinetic Theory addresses. As matter (the system) exhibits
melting, evaporation, or sublimation heat energy is absorbed by the matter and intermolecular forces are
weakened or become non-existent. Each of these phase changes are classified as endothermic reactions
because heat energy is absorbed by matter (system). As matter (the system) exhibits condensation,
freezing, or deposition heat energy is released by matter and intermolecular forces are strengthened. Each
of these phase changes are classified as exothermic because heat energy is released by matter (system).
The strength of the intermolecular forces is what gives each state of matter their physical properties.
8. a. Heat capacity is the amount of heat energy needed to raise the temperature of the system 1 0C.
b. Heat capacity depends upon the system’s mass and chemical composition.
c.
Specific Heat Capacity is the amount of heat energy needed to raise one gram of the system 1 0C.
d. C = q/ (mass * change in temperature)
9. a. 2.0 J/g*0C olive oil
b. 0.076 J/g*0C Al
c. 7,400 J of H2O
d. 5.9 cal of Hg
e. 3 J/g*0C Ag