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1. Calculate the DH^o_rxn from the DH^o_f for the following reaction:

a) PbO _(s) + CO _(g) -------> Pb _(s) + CO_{2 (g)}DH^o_rxn = -65.7 kJ

b) SiH₄_(g) + 2 O_{2 (g)} -------> SiO₂_(s) + 2 H₂O _(l)DH^o_rxn = -1516.8 kJ

c) 2 FeS₂_(s) + 5.5 O_{2 (g)} -------> Fe₂O₃_(s) + 4 SO₂_(g)DH^o_rxn = -1656.4 kJ

2. Determine the DH_rxn using Hess' Law

a) Determine the enthalpy of formation for MnO₂_(s)

Mn _(s) + O_{2 (g)} --------> MnO₂_(s)

Given:

4 Al_(s) + 3 O_{2 (g)} -------> 2 Al₂O₃_(s) DH_rxn = -3352 kJ/mol

4 Al_(s) + 3 MnO₂_(s) -------> 3 Mn_(s) + 2 Al₂O₃_(s) DH_rxn = -1937 kJ/mol

DH_f = -471.7 kJ/mol

b) Determine the heat of hydrogenation for

C₃H₄_(g) + 2 H₂_(g) --------> C₃H₈_(g)

Given:

2 H₂_(g) + O_{2 (g)} -------> 2 H₂O_(l) DH_rxn = -571.6 kJ/mol

C₃H_{4 (g)} + 4 O_{2 (g)} -------> 3 CO_{2 (g)} + 2 H₂O_(l) DH_rxn = -1937 kJ/mol

C₃H_{8 (g)} + 5 O_{2 (g)} -------> 3 CO_{2 (g)} + 4 H₂O_(l) DH_rxn = -2220 kJ/mol

DH_rxn = -288.6 kJ/mol