Chapter 5
Supplemental Instruction
Iowa State University
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Course:
Instructor:
Date:
Carlie
Chem 177
Schewe-Miller
2-21-12
1. Calculate the standard reaction enthalpy, H, for the reaction:
C6H4O2 (l) + 6O2 (g)  6 CO2(g) + 2H2O(l)
Substance
Hf
C6H4O2 (l)
-185.7 kJ/mol
CO2(g)
-393.5 kJ/mol
H2O(l)
-285.8 kJ/mol
2.) A 6.63 g sample of aluminum initially at 19.1°C absorbs 73.7 J of energy which causes the
temperature to increase to 31.4°C. According to this experiment what is the specific heat of
aluminum?
3.) In an endothermic reaction the temperature of the solution goes (up/down).
4.) The specific heat of iron metal is 0.450 J/g-K. How many J of heat are necessary to raise the
temperature of 1.50-kg block of iron from 25.0°C to 88.5°C?
5.) You have 10 g of copper, 10 g of iron and 10 g of water. All three samples start at 25 °C and
have 100 J of heat added. Rank the samples from coolest to warmest after the heat has been
added.
Substance Specific Heat
Cu
0.387 J/g °C
Fe
0.4998 J/g °C
H2O
4.184 J/g °C
a) Cu, Fe, H2O
b) Fe, Cu, H2O
c) H2O, Fe, Cu
d) Fe, H2O, Cu
e) H2O, Cu, Fe
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6.) Which one of the following conditions would always result in an increase in the internal
energy of a system?
a) The system loses heat and does work on the surroundings.
b) The system gains heat and does work on the surroundings.
c) The system loses heat and has work done on it by the surroundings.
d) The system gains heat and has work done on it by the surroundings.
e) None of the above is correct.
7.) Under what condition(s) is the enthalpy change of a process equal to the amount of heat
transferred into or out of the system?
(a) temperature is constant
(b) pressure is constant
(c) volume is constant
a) a only
b) b only
c) c only
d) a and b
e) b and c
8.) The temperature of a 15 g sample of Lead (Pb) metal increases from 22.00°C to 37.00°C
upon the addition of 29.00 J of heat. The specific heat capacity of Lead (Pb) is _____J/g-K.
a) 7.8
b) 1.9
c) 29
d) 0.13
e) -29