Question

At a certain temperature, the following reactions have the equilibrium constants shown. S(s) + O_2(g) rightwardsharpoonoverleftwardsharpoon SO_2(g) K_c = 10^2S(s) + 3O_2(g) rightwardsharpoonoverleftwardsharpoon 2SO_2(g) k_ = 9.8 times 10^Calculate the equilibrium constant, K_c. for the following reaction at that temperature. 2SO_2(g) + O_2(g) rightarrow 2SO_3(g)

Answer 1

Given,

At a certain temperature the following reactions have the constants shown as----
S(s) + O₂(g)<----> SO₂(g) KC₁ = 4.2 x 10⁵²
2 S(s) + 3 O₂(g) <----> 2 SO₃(g) ,Kc₂ = 9.8 x 10¹²⁸

2 SO₂(g) + O₂(g) -----> 2 SO₃(g) . Kc₃ =?

Now,

For reaction,

S(s) + O₂(g)<----> SO₂(g)

Kc₁ =[SO₂] / [S][O₂] =4.2 x 10⁵²

For reaction,

2 S(s) + 3 O₂(g) <----> 2 SO₃(g)

Kc₂ =[SO₃]² / [S]²[O₂]³ = 9.8 x 10¹²⁸

So, for 2 SO₂(g) + O₂(g) -----> 2 SO₃(g)

Kc₃ =[SO₃]² /[SO₂]²[O₂]

= Kc₂ / Kc₁² [rearranging we get these ]

= 9.8 x 10¹²⁸ /(4.2 x 10⁵² )²

  = 9.8 /17.64 x10^128-104

=5.55 x 10^-1 x 10²⁴

=> Kc₃ =5.55 x 10²³