Question 4 of 69beginner🔧 ApplyShort Answer2 marks

Write the expression for the equilibrium constant, KcK_c for each of the following reactions: (i) 2NOCl(g)⇌2NO(g)+Cl2(g)2NOCl(g) \rightleftharpoons 2NO(g) + Cl_2(g) (ii) 2Cu(NO3)2(s)⇌2CuO(s)+4NO2(g)+O2(g)2Cu(NO_3)_2(s) \rightleftharpoons 2CuO(s) + 4NO_2(g) + O_2(g) (iii) CH3COOC2H5(aq)+H2O(l)⇌CH3COOH(aq)+C2H5OH(aq)CH_3COOC_2H_5(aq) + H_2O(l) \rightleftharpoons CH_3COOH(aq) + C_2H_5OH(aq) (iv) Fe3+(aq)+3OH−(aq)⇌Fe(OH)3(s)Fe^{3+}(aq) + 3OH^-(aq) \rightleftharpoons Fe(OH)_3(s) (v) I2(s)+5F2(s)⇌2IF5I_2(s) + 5F_2(s) \rightleftharpoons 2IF_5

(i)
Answer

Kc=[NO]2[Cl2][NOCl]2K_c = \frac{[NO]^2[Cl_2]}{[NOCl]^2}

(ii)
Answer

Kc=[NO2]4[O2]K_c = [NO_2]^4[O_2]

(iii)
Answer

Kc=[CH3COOH][C2H5OH][CH3COOC2H5]K_c = \frac{[CH_3COOH][C_2H_5OH]}{[CH_3COOC_2H_5]}

(iv)
Answer

Kc=1[Fe3+][OH−]3K_c = \frac{1}{[Fe^{3+}][OH^-]^3}

(v)
Answer

Kc=[IF5]2K_c = [IF_5]^2

Explanation

The equilibrium constant expression, KcK_c, includes the molar concentrations of gaseous and aqueous species, each raised to the power of their stoichiometric coefficients. Pure solids and pure liquids are omitted from the expression because their active masses are constant.

In reaction (ii), Cu(NO3)2Cu(NO_3)_2 and CuOCuO are solids, so they are ignored. In (iii), H2OH_2O is a pure liquid and is ignored. In (iv), Fe(OH)3Fe(OH)_3 is a solid and is ignored. In (v), I2I_2 and F2F_2 are solids and are ignored, leaving only the concentration of IF5IF_5.

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