Find the enthalpy change for the reaction 4NH3(g) + 5O2(g) --> 4NO(g) + 6H2O(g)
when:
N2(g) + O2(g) --> 2NO(g) ΔH = -180.5 kJ
N2(g) + 3H2(g) --> 2NH3(g) ΔH = -91.8 kJ
H2 + 1/2O2 --> H2O(g) ΔH = -241.8 kJ

Use the formula ∆H = m x s x ∆T to solve.

Once you have m, the mass of your reactants, s, the specific heat of your product, and ∆T, the temperature change from your reaction, you are prepared to find the enthalpy of reaction. Simply plug your values into the formula ∆H = m x s x ∆T and multiply to solve.

every chemical equation adheres to the law of conservation of mass, which states that matter cannot be created or destroyed. therefore, there must be the same number of atoms of each element on each side of a chemical equation.