Record your values for ΔHA and ΔHB below: Mg (s) + 2 HCl (aq) →MgCl2 (aq) + H2 (g) ∆HA = __-4.70 x 105 kJ/mol Mg_ MgO (s) + 2 HCl(aq) → MgCl2 (aq) + H2O (l) ∆HB = __-150 kJ/mol MgO___ _ In orderto calculate the heat of formation of MgO (∆Hf MgO), you will alsoneed one additional enthalpy value, the enthalpy of formation ofliquid water. Look this value up in a textbook and record it below.Be sure you record the value for liquid water, not gaseous water.H2 (g) + ½ O2 (g) → H2O (l) ∆Hf = _-285.8 kJ/mol__ Calculations:Show all of your work, with units. Record answers with correctsignificant figures. 1. Using the information determined above andHess’s Law, the heat of formation (∆Hf) for MgO can be obtained.Rearrange the three equations above to determine ï„H for: Mg (s) + ½O2 (g) ï‚Š MgO (s): show your work, and pay attention to sig figs! Mg(s) + ½ O2 (g) → MgO (s) H2 (g) + ½ O2 (g) → H2O (l) Your value for∆Hf MgO(pay attention to sig figs!) = __________________ 2. Look upthe theoretical (textbook) value for the heat of formation of MgOand calculate your percent difference to the correct significantfigures. Textbook value for ∆Hf MgO = __-601.6__ kJ/mol %difference = ____________________
