Question

1.A system releases 691 kJ of heat and does 100 kJ of work on the surroundings.

What is the change in internal energy of the system? Express your answer to 2 sig figs.

2.If 1.7 g of matter were converted to energy, how much energy would be formed?

Express your answer using two significant figures.

3.Hydrogen gas reacts with oxygen to form water.

2H2(g)+O2(g)→2H2O(g)ΔH=−483.5kJ

Determine the minimum mass of hydrogen gas required to produce 524 kJ of heat.

Express your answer to three significant figures and include the appropriate units.

4. Calculate ΔHrxn for the following reaction:
5C(s)+6H2(g)→C5H12(l)
Use the following reactions and given ΔH′s.
C5H12(l)+8O2(g)→5CO2(g)+6H2O(g), ΔH= -3244.8 kJ
C(s)+O2(g)→CO2(g), ΔH= -393.5 kJ
2H2(g)+O2(g)→2H2O(g), ΔH= -483.5 kJ

Express answer to 4 sig figs.

5.

Use the ΔH°_f and ΔH°_rxn information provided to calculate ΔH°_f for IF:

	ΔH°f (kJ/mol)	IF7(g) + I2(g) → IF5(g) + 2 IF(g)	ΔH°rxn = -89 kJ
IF7(g)	-941
IF5(g)	-840

a.101 kJ/mol

b.-146 kJ/mol

c. -190 kJ/mol

d. -95 kJ/mol

e. 24 kJ/mol