Question

Ammonia reacts with oxygen to produce nitrogen and water?

Answer 1

Answer:

- 1276.2 kJ.

Explanation:

• We can use the relation:

ΔHrxn = ∑(n ΔHproducts) - ∑(n ΔHreactants)

• For the reaction: 4NH₃ + 3O₂ → 2N₂ + 6H₂O,

∴ ΔHrxn = [(6 x ΔHf H₂O) + (2 x ΔHf N₂)] - [(4 x ΔHf NH₃) + (3 x ΔHf O₂)],

• The heat of formation of the elements is equal zero (ΔHf N₂ & ΔHf O₂ = 0).

∴ ΔHrxn = [(6 x - 241.8 kJ/mol) + (2 x 0)] - [(4 x -45.9 kJ/mol) + (3 x 0)] = -1450.8 kJ/mol + 183.6 kJ/mol = - 1276.2 kJ.

Answer 2

Answer;

  = -1267.2 kJ

Explanation;

The equation for the reaction is;

4NH3 + 3O2 → 2N2 + 6 H2O

ΔHrxn = ∑(ΔHf,products) - ∑(ΔHf. reactants)

ΔHf of NH3 =-45.9 kJ/mol , while ΔHf of H2O = -241.8 kJ/mol

Therefore;

ΔHrxn = 6(-241.8 kJ/mol) - 4(45.9 kJ/mol)

          = -1450.8 - (-183.6)

          = -1450.8 + 183.6)

        = -1267.2 kJ