A student ran the following reaction in the laboratory at 600 K: COCl2(g) CO(g) + Cl2(g) When he introduced COCl2(g) at a pressure of 0.822 atm into a 1.00 L evacuated container, he found the equilibrium partial pressure of COCl2(g) to be 0.351 atm. Calculate the equilibrium constant, Kp, he obtained for this reaction.

Respuesta :

Answer:

the Kp=0.171 atm

Explanation:

For the reaction

COCl₂(g) →  CO(g) + Cl₂(g)

since the temperature remains constant , the Kp will remain constant .

Kp = pCO*pCl₂/ pCOCl₂

since for every mole that is converted , a mole of CO(g) and a mole of Cl₂(g) are generated , then

denoting 1 as COCl₂ , 2 as CO  , 3 as Cl₂ , 0 as initial state and X as conversion , then the moles of each component will be given by

n₁= n₀*(1-X) , n₂ = n₀*X  , n₃ = n₀*X

the final number of total moles will be

nf = n₁ + n₂ + n₃ = n₀*(1-X)  + n₀*X + n₀*X  = n₀ + n₀*X = n₀ ( 1+X)

then assuming ideal gas behaviour and that the container is rigid (V=constant)

P₀*V= n₀*R*T and Pf*V= nf*R*T

dividing both equations

Pf/ P₀ =  n₀*(1+X) /  n₀ = (1+X)

X = 1- Pf/ P₀

replacing values

X = 1- Pf/ P₀ = 1- 0.351 atm/0.822  atm = 0.573

thus using Dalton's law

p₁ = Pf*x₁ = Pf*n₀*(1-X)/[n₀ ( 1+X)}  =Pf*(1-X)/(1+X)

p₂= Pf*x₂  = Pf*n₀*X/[n₀ ( 1+X)}  =Pf*X/(1+X)

p₃= Pf*x₃  = Pf*n₀*X/[n₀( 1+X)}  =Pf*X/(1+X)

then the equilibrium constant will be

Kp= p₂*p₃/p₁ = Pf*X²/[(1-X)*(1+X)] = Pf*X²/(1- X²)

replacing values

Kp= Pf*X²/(1- X²) = 0.351 atm * 0.573²/(1-0.573²) = 0.171 atm

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