Honors Chemistry
Thermochemistry
Name:
1.
Period:
Are the following processes exothermic or endothermic?
a. When solid KBr is dissolved in water, the solution gets colder.
b. Natural gas (CH3) is burned in a furnace.
c. When concentrated H2SO4 is added to water, the solution gets very hot.
d. Water is boiled in a teakettle.
2. For the reaction
S(s) + O2(g)
SO2(g)
ΔH = -296 kJ/mol
a. How much heat is evolved when 275g sulfur is burned in excess O2?
b. How much heat is evolved when 150.g sulfur dioxide is produced?
3. The specific heat capacity of aluminum is 0.900 J/g oC
a. Calculate the energy needed to raise the temperature of a 8.50 x102 g block of aluminum from
22.8 oC to 94.6 oC.
b. Calculate the molar heat capacity of aluminum.
4. It takes 78.2 J to raise the temperature of 45.6 g lead by 13.3oC. Calculate the specific heat capacity
and molar heat capacity of lead.
5. A 30.0g sample of water at 280 K is mixed with 50.0g of water at 330 K. Calculate the final
temperature of the mixture assuming no heat loss to the surroundings.
6. A 150.0 g sample of a metal at 75.0oC is added to 150.0 g H2O at 15.0oC. The temperature of the
water rises to 18.3oC. Calculate the specific heat capacity of the metal, assuming that all the heat lost by
the metal is gained by the water.
7. Consider the dissolution of CaCl2:
CaCl2(s)
Ca2+ (aq) + 2Cl- (aq)
ΔH= -81.5 kJ
An 11.0g sample of CaCl2 is dissolved in 125 g of water with both substances at 25.0oC. Calculate
the final temperature of the solution assuming no heat lost to the surroundings and assuming the
solution has a specific heat capacity of 4.18J/goC.
8. A 46.2 g sample of copper is heated to 95.4 ºC and then placed in a calorimeter containing 75.0 g
water at 19.6ºC. The final temperature of the metal and water is 21.8º C. Calculate the specific heat
of copper, assuming all the heat lost by the copper is gained by the water.