Equation 1: Mg(s) + O2(g) MgO(s)

Equation 2: MgO(s) + 2HCl(aq) MgCl2(aq) + H2O(l)

Equation 3: Mg(s) + 2HCl(aq) MgCl2(aq) + H2(g)

Equation 4: H2(g) + O2(g) H2O(l) + 285.8kJ

Experiment 1: 50mL of 1.00 mol/L HCl added to the calorimeter, then 0.50g of MgO(s) powder added. Temperature Change : 19C -> 20C

Experiment 2: 50mL of 1.00 mol/L HCl added to the calorimeter, then 0.30g of Mg(s). Temperature Change : 19C -> 44C

1. Determine the enthalpy of reactions for Experiment 1 (Equation 2) and 2 (Equation 3).

2. Write thermochemical equations for Experiment 1 (Equation 2) and 2 (Equation 3) using H notation.

3. Using Hesss Law, algebraically combine Equations 2, 3, and 4 and their corresponding H values to determine the molar enthalpy of combustion of magnesium for Equation 1.

4. Calculate the accepted value of the Hcomb (Equation 1) using heats of formation.

5. Compare your result to the accepted value of Hcomb calculated above. Calculate your percent error.