Question

1. Write the mathematical expression for the reaction quotient, Qc, for each of the following reactions: (a) N2(g)+3H2(g) ⇌ 2NH3(g) (b) 4NH3(g)+5O2(g) ⇌ 4NO(g) + 6H2O(g) (c) NH4Cl(s) ⇌ NH3(g) + HCl(g) (d) 2Pb(NO3)2(s) ⇌ 2PbO(s) + 4NO2(g) + O2(g) (e) S8(g) ⇌ 8S(g)

Answer 1

Answer:

(a) Qc = [NH₃]² / [N₂] × [H₂]

(b) Qc = [NO]⁴ × [H₂O]⁶ / [NH₃]⁴ × [O₂]⁵

(c) Qc = [NH₃] × [HCl]

(d) Qc = [NO₂]⁴ × [O₂]

(e) Qc = [S]⁸ / [S₈]

Explanation:

The reaction quotient (Qc) is equal to the product of the concentrations (at any time) of the products raised to their stoichiometric coefficients divided by the the product of the concentrations (at any time) of the reactants raised to their stoichiometric coefficients. In only includes gases and aqueous species.

(a) N₂(g) + 3 H₂(g) ⇌ 2 NH₃(g)

Qc = [NH₃]² / [N₂] × [H₂]

(b) 4 NH₃(g) + 5 O₂(g) ⇌ 4 NO(g) + 6 H₂O(g)

Qc = [NO]⁴ × [H₂O]⁶ / [NH₃]⁴ × [O₂]⁵

(c) NH₄Cl(s) ⇌ NH₃(g) + HCl(g)

Qc = [NH₃] × [HCl]

(d) 2 Pb(NO₃)₂(s) ⇌ 2 PbO(s) + 4 NO₂(g) + O₂(g)

Qc = [NO₂]⁴ × [O₂]

(e) S₈(g) ⇌ 8 S(g)

Qc = [S]⁸ / [S₈]