AP Chemistry
Test 5-Thermo Test
Name_______________________________
October 22, 2012
Directions: Show all of your work to receive full credit.
1. Calculate ΔE for a system undergoing an endothermic process in which 15.6 kJ of heat
flows and where 1.4 kJ of work is done on the system.
2. Calculate the ΔH°rxn for the following:
3 Al(s) + 3 NH4ClO4(s) → Al2O3(s) + AlCl3(s) + 3 NO(g) + 6 H2O(g)
Given the following values:
Substance
ΔHf° (kJ/mol)
NH4ClO4(s) -295
Al2O3(s)
-1676
AlCl3(s)
-704
NO(g)
90.0
H2O(g)
-242
3. Given the following equations
H3BO3(aq) → HBO2(aq) + H2O(l)
H2B4O7(aq) + H2O(l) → 4 HBO2(aq)
H2B4O7(aq) → 2 B2O3(s) + H2O(l)
ΔHrxn = -0.02 kJ/mol
Δ Hrxn = -11.3 kJ/mol
Δ Hrxn = 17.5 kJ/mol
find the ΔH for this overall reaction
2 H3BO3(aq) → B2O3(s) + 3 H2O(l)
4. When a 6.50 g sample of solid sodium hydroxide dissolves in 100.0 g of water in a
coffee-cup calorimeter, the temperature rises from 21.6 oC to 37.8oC. Calculate the ΔH
(kJ/mol). For the solution process:
NaOH(s)  Na+(aq) + OH-(aq)