1 – Heat, Calorimetry and Enthalpy
Name:
1. How much heat does a 23.0-g ice cube absorb as its temperature increases from -17.4°C to
0.0°C?
2. Copper metal has a specific heat of 0.385 J/g·°C and a melting point of 1083°C. Calculate the
amount of heat required to raise the temperature of 22.8 g of copper from 20.0°C to 875°C.
3. A 15.6-g sample of ethanol absorbs 868 J as it is heated. If the initial temperature of the
ethanol was 21.5°C, what is the final temperature of the ethanol?
1 – Heat, Calorimetry and Enthalpy
4. A 77.5-g sample of an unknown solid is heated to 62.5°C and placed into a calorimeter
containing 93 g of water at 23.3°C. If the final temperature of the solid sample and the water is
26.2°C, what is the specific heat of the solid?
5. A 50.6-g sample of iron metal is heated and put into 104 g of water at 19.7°C in a calorimeter.
If the final temperature of the iron sample and the water is 24.3°C, what was the temperature
of the iron sample when it was placed in the water?
6. If 40.0 g of water at 70.0°C is mixed with 40.0 g of ethanol at 10.0°C, what is the final
temperature of the mixture?
1 – Heat, Calorimetry and Enthalpy
7. In a coffee-cup calorimeter, 100.0 g of H2O and 100.0 mL of HCl are mixed. The HCl had an
initial temperature of 44.6°C and the water was originally at 24.6°C. After the reaction, the
temperature of both substances is 31.3°C.
a. Is the reaction exothermic or endothermic? Explain.
b. Calculate how much heat the water lost or gained.
8. If 22.0 grams of propane (C3H8) is combusted in a bomb calorimeter containing 3.25 liters of
water, calculate the molar heat of combustion of propane if the water temperature rises 29.5°C.
1 – Heat, Calorimetry and Enthalpy
9. From the following data at 25°C,
H2(g) + Cl2(g) ® 2 HCl(g)
2 H2(g) + O2(g) ® 2 H2O(g)
DH = -185 kJ
DH = -483.7 kJ
Calculate DH at 25°C for the reaction below.
4 HCl(g) + O2(g) ® 2 Cl2(g) + 2 H2O(g)
10. From the following data at 25°C,
H2(g) + Cl2(g) ® 2 HCl(g)
DH = -185 kJ
H2(g) + Br2(g) ® 2 HBr(g)
DH = -73 kJ
Determine DH for this single-displacement reaction.
Cl2(g) + 2 HBr(g) ® 2 HCl(g) + Br2(g)
1 – Heat, Calorimetry and Enthalpy
11. From the following data at 25°C,
2 CO(g) + O2(g) ® 2 CO2(g)
DH = -566 kJ
2 H2(g) + O2(g) ® 2 H2O(l)
DH = -572 kJ
2 CH3OH(l) + 3 O2(g) ® 2 CO2(g) + 4 H2O(l)
DH = -1452 kJ
Determine DH for the reaction of carbon monoxide and hydrogen to form methanol (CH3OH).
CO(g) + 2 H2(g) ® CH3OH(l)
12. Find the standard enthalpy of formation for ethylene, C2H4(g), given the following data.
C2H4(g) + 3 O2(g) ® 2 CO2(g) + 2 H2O(l)
C(s) + O2(g) ® CO2(g)
H2(g) +
1
O2(g)
2
® H2O(l)
DH° = -1411 kJ
DH° = -393.5 kJ
DH° = -285.8 kJ