Question

Write the mathematical expression for the reaction quotient (Qc) for the following reactions:

a) N₂ (g) + 3H₂ (g) ⇌ 2NH₃ (g)

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

c) N2O₄ (g) ⇌ 2NO₂ (g)

d) CO₂ (g) + H₂ (g) ⇌ CO (g) + H₂O (g)

e) NH₄Cl (s) ⇌ NH₃ (g) + HCl (g)

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

g) 2H₂(g) + O₂ (g) ⇌ 2H₂O (l)

h) S₈ (g) ⇌ 8_S (g)

Answer 1

The reaction quotient (Qc) for chemical reactions is derived from the concentrations of gaseous or aqueous products and reactants, with coefficients serving as exponents. Solids and liquids are omitted in these calculations. Notably, for pure elements in their standard state, Qc expressions are generally not applicable.

Step-by-step explanation:

Mathematical Expression for the Reaction Quotient (Qc)

The reaction quotient (Qc) for a chemical reaction at a given moment is calculated based on the molar concentrations of the reactants and products raised to the power of their coefficients from the balanced chemical equation. Here are the expressions for Qc for the given reactions:

• • (a) Qc = [NH3]2 / ([N2] * [H2]3)
  • (b) Qc = ([NO]4 * [H2O]6) / ([NH3]4 * [O2]5)
  • (c) Qc = [NO2]2 / [N2O4]
  • (d) Qc = ([CO] * [H2O]) / ([CO2] * [H2])
  • (e) Qc = ([NH3] * [HCl]) / (Because NH4Cl is a solid, it is not included in the expression)
  • (f) Qc = ([NO2]4 * [O2]) / (Because Pb(NO3)2 and PbO are solids, they are not included in the expression)
  • (g) Qc = (Because H2O is a liquid, it is not included in the expression)
  • (h) Qc = [S]8 / [S8] (Because S is an element in its standard state, this expression is not typically used)