Question

Pre-lab Questions for Experiment #11 Hess's Law with Computers 1) Using the following data, NaOH () - Na' (aq) + OH (aq) ΔΙΙ "-42.9 kJ/mol =-98.8 kJ/mol NaOHis).HUaq) + Cl.(aq)....-11:0(1) + Na. (ap-Craq) Calculate the heat of reaction, AH, for ΔΙΙ 2) Methane, the main constituent of natural gas, burns in oxygen to yield carbon dioxide and water: CH(g) + 2 02(g)CO(g) +2 H:00) Use the following information to calculate ΔΗ, in kilojoules for the combustion of methane CH(g) + O2(g)CH20(g)+ HO(g) H2O(g) ΔΗ。.. 275,6 kJ Δ1r--S267 kJ CH20(g) + O2(g) > CO2(g) + H:00)->H:0(g) data: 3) Use the Born-Haber cycle to calculate the lattice energy of MgO (s) given the following ΔΗ(sublimation) Mg 130 kJ/mol 11 (Mg) = 738.1 kJ/mol 2 (Mg) 1450 kJ/mol Bond energy (O-O) 498.7 kJ/mol EA (O) 141 kJ/mol EA (O)780 kJ/mol AHt (MgO(s)) 601.8 kJ/mol

Answer 1

Ans 1 :

The desired reaction can be obtained by adding :

= (reverse of reaction1 ) + (reaction 2 )

Using Hess's law , the heat ofreaction for the desired reaction is given as :

= -(-42.9) + (-98.8)

= -55.9 KJ/mol