Calculate enthalpy change

Question

Use values for the standard enthalpies of formation to calculate the enthalpy change for the reaction below:

2NH3(g)+3O2(g)+ CH4(g) → 2HCN(g) +6H2O(g)

Give the quantity and unit (kJ) and don't forget the + or - sign.

Answer 1

∆Hrxn = ∑[2∆H_fHCN(g) + 6∆H_fH2O(g)] - [2∆H_fNH3(g) + ∆H_fCH4(g)]

Look up the values in a table and perform the above calculation. Note that ∆H_f for 3O₂(g) is not included as the value is zero.

Answer 2

This question involves using standard enthalpies of formation which can be looked up through a table of values in any given textbook in the appendix or online. To calculate the the change in enthalpy is going to be products minus reactants and you must include the stociometric coefficients from the balanced chemical equation in your calculations.