Chemistry Practice Problems
Thermochemistry: Calculating Enthalpy Change
Problems:*
1. Use the table of enthalpies of formation provided below to determine the standard
enthalpy of the following reaction.
2ZnS(s) + 3 O2(g) à 2ZnO(s) + 2SO2(g)
1. Substance
2.
o
Hf
Δ
, kJ/mol
3. Substance
4.
o
Hf
Δ
, kJ/mol
5. ZnS(s)
6. –202.9
7. SO2(g)
8. –296.4
9. ZnO(s)
10. –348.0
11. SO3(g)
12. –395.2
2. Use the data in the table provided below to verify that the heat capacity of the coffee cup
calorimeter (constant pressure calorimeter) is negligible in the following calorimetry
experiment.
In a coffee cup calorimeter, 25.00 mL of 0.100 M-HCl at 25.20 oC and 10.00 mL of
0.125 M-Ba(OH)2 at 25.20 oC are combined. The reaction mixture reaches a final
temperature of 26.15 oC.
)(OH
2
o
f
lHΔ
–285.8 kJ/mol
Density of solution
1.001 g/mL
)(H
o
f
aqH
+
Δ
0.0 kJ/mol
Specific Heat of solution
4.184 g/mL
)(OH
-o
f
aqHΔ
–229.94 kJ/mol
