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Consider the following reaction:

2 H2O(g) + 2 SO2(g) _ 2 H2S(g) + 3 O2(g)

A reaction mixture initially contains 2.8 M H2O and 2.6 M SO2. Determine the equilibrium

concentration of H2S if Kc for the reaction at this temperature is 1.3 _10^_6

Verified Answer :

syed514

Kc = [H2S]²[O2]³ / [H2O]²[SO2]²

Let x be the moles of H2S formed. Each mole of H2S takes one each mole of H2O and SO2 so after the reactions

[H2O] = 2.8 - x and [SO2] = 2.6 - x also for each mole of H2S, 1.5 moles of O2 are formed, so [O2] = 1.5x

Kc = x²(1.5x)³ / (2.8 - x)²(2.6 - x)²
Thus use 2.8 - x = 2.8 and 2.6 - x = 2.6 in the above equation for Kc:

Kc = x²(1.5x)³ / 2.8²2.6² = 3.375x^5 / 2.8²2.6² = 0.06368x^5

x^5 = 1.310^-6 / 0.06368 = 2.0414*10^-5

x = 0.115M

hope it helps

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