Answer to Question #286322 in Physical Chemistry for Ryan

Question

Equilibrium Constant

Q1

for both of the following equilibria, write the expression for the equilibrium constant K_c and state it’s units:

i) H₂(g) + I₂ (g) —-> <—— 2HI (g) (2 marks)

ii) 2SO₂ (g) + O₂(g) ——> <—— 2SO₂ (g) (2 marks)

Q2

the reaction for the formation of hydrogen bromine does not go to completion but reaches an equilibrium, as shown:

H₂(g) + Br₂ —-> <—— 2HBr(g)

a mixture of 1.9 mol of H₂ and 1.9 of Br was prepared and allowed to reach equilibrium in a closed vessel on 250 cm³ capacity. The resulting equilibrium mixture was found to contain 3.0 moles of HBr. Calculate the value of K. (3 marks please detailed answers with explanation🙏🏾🙏🏾🙏🏾🙏🏾)

Answer 1

Q1

(i) $k_c=\frac{[HI]^2}{[H_{2}][I_{2}]}$

Units Mole L^-1

(ii) $k_c = \frac{[SO_2]^2}{[SO_2]^2[O_2]}$

Units Mole^-1L

Q2

$\begin{matrix} & H_2+ &Br_2&\rightleftharpoons&2HBr \\ I&1.9&1.9& & 0\\ C&x&x&&2x\\ E&1.9-x&1.9-x&&2x \end{matrix}$

But $2x=3\implies\>x=1.5$

$[H_2]=1.9-1 .5$

$=0.4mol/250cm^3$

$=1.6mol/L$

$[Br_2]=1.6mol/L$

$[HBr]=\frac{3×1000}{250}=12mol/L$

$K_c=\frac{[HBr]^2}{[H_2][Br_2]}=\frac{12^2}{1.6×1.6}=56.25$