Honors Chemistry
Name: _____________________________________ Date: _______________ Mods: ____________
Ch. 5 Review
1. Matching: Match the following vocabulary terms to their correct definitions/descriptions.
A
state function
The ability to do work or transfer heat
B
heat
C
exothermic
D
endothermic
E
calorimetry
F
kinetic energy
The energy a substance contains as a result of its
chemical composition (the bonds within the compound)
Quantitative measurement of the amount of heat within a
substance
A property of a system that is independent of the path
taken and depends only on the final and initial conditions
Energy used to move an object (that has mass) over a
distance
A process which absorbs heat from its surroundings
G
potential energy
The amount of heat required to raise 1 gram of a
substance 1°C
H
energy
I
work
The experimental measurement of the quantity of heat
transferred during a physical or chemical reaction
A process which releases heat to its surroundings
J
temperature
K
specific heat capacity
Energy of motion that is directly tied to the temperature, or
thermal energy, of a substance
Energy transferred as a result of differences in
temperature
2. The amount of heat (q) released or absorbed by a chemical reaction is equal to the enthalpy of the
reaction (ΔH) if the _____________________________ is held constant.
3. What are the two conditions (of temperature & pressure) are required for a reaction to be
considered a “standard state reaction”?
4. What does the first Law of Thermodynamics state? How does this apply to the transfer of energy
between a system and surroundings?
5. Classify each of the following as either EXOthermic or ENDOthermic:
a) ___________ surroundings get hot
f) ___________ ΔH is negative
b) ___________ enthalpy diagram is “uphill”
g) ___________ enthalpy diagram is “downhill”
c) ___________ heat is a product
h) ___________ surroundings get cold
d) ___________ ΔH is positive
i)
___________ products have higher enthalpy
e) ___________ reactants have higher enthalpy
j)
___________ heat is a reactant
6. Determine the change in internal energy, ΔE, in kilojoules for each system below:
a) A windmill emits 1290.6 calories of heat while doing 129 kJ of work done on its surroundings.
What is the internal energy change of the windmill?
b) A snow plow has 41 kJ of work done on while it releases 3.8 kcal of heat to its surroundings.
What is the internal energy change of the snow plow?
7. Write the enthalpy of formation equation, including the ΔHf°, for the formation of solid rubidium
chlorate.
8. A layer of copper welded to the bottom of a skillet weighs 125 g. How much heat is needed to
raise the temperature of the copper layer from 25˚C to 300˚C if the specific heat capacity of Cu is
0.387 J/g°C?
9. Water is cooled from an initial temperature of 74.5°C down to 3.9°C. This decrease in temperature
releases 162.8 kJ of heat. What was the mass, in grams, of water cooled?
10. In a purity check for industrial diamonds, a 10.25-carat (1 carat = 0.20 g) diamond is heated to
73.0°C and immersed in 26.05 g of water inside a calorimeter. The initial temperature of the water
is 27.0°C. Calculate the final temperature of water and diamond (Cp(diamond) = 0.519 J/g°C).
11. Given the following information, calculate the enthalpy of the reaction between gaseous
hydrochloric acid and solid sodium nitrite: HCl (g) + NaNO2 (s)  HNO2(l) + NaCl (s)
Reaction A:
2 NaCl (s) + H2O (l)  2 HCl (g) + Na2O (s)
ΔHA = +507.0 kJ
Reaction B:
Reaction C:
NO (g) + NO2 (g) + Na2O (s)  2 NaNO2 (s)
NO (g) + NO2 (g)  N2O (g) + O2 (g)
ΔHB = - 427.0 kJ
ΔHC = - 43.0 kJ
Reaction D:
2 HNO2 (l)  N2O (g) + O2 (g) + H2O (l)
ΔHD = +34.0 kJ
12. Ammonia gas (NH3) and oxygen gas react to produce nitrogen gas and water vapor.
a) Write the balanced chemical equation to express this reaction
b) Calculate the standard enthalpy change, H°rxn, for this reaction.
c) Re-write the reaction above as a thermochemical equation where the enthalpy of reaction is
expressed as either a reactant or product.
13. The standard heat of formation, ΔHf°, for gaseous sulfur dioxide (SO2) is -297 kJ/mol. How many
kJ of energy are given off when 25.0 g of SO2 (g) is produced from its elements?
14. The combustion of one mole of liquid pentane, C5H12, releases 3003.5 kJ of heat. Determine the
heat of formation, ΔHf°, of liquid pentane.
15. Questions a-e are based on the following reaction:
2 N2O5(g) + 64.5 kJ  4 NO2(g) + O2(g)
a) Is the above reaction exothermic or endothermic? _____________________________
b) Which has a higher enthalpy, the reactants or products? ________________________
c) If 220 grams of dinitrogen pentoxide are decomposed, what would be the associated enthalpy
change (in kJ)?
d) If the enthalpy change associated with this reaction is 52.8 kJ, what mass of nitrogen dioxide
will be produced?
e) Draw an enthalpy diagram below to describe this reaction.