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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: doreen on April 03, 2004, 07:39:01 AM

Title: Gas Laws, Equilibrium
Post by: doreen on April 03, 2004, 07:39:01 AM

consider the reaction of A(g)+B(g)yields C(g) for which Kc=130. assume 0.406 mole C(g) is placed in the cylinder below. the temperature is 300.0 K, and the barometric pressure on the piston (which is assumed to be massless and frictionless) is constant at 1.00 atm. the original volume [before the 0.406 mol C(g) begins to decompose] is 10.00 L. What is the volume of the cylinder at equilibrium?

Title: Re:equilibrium challenges
Post by: Mitch on April 03, 2004, 08:53:58 PM

Just so you can get a sense of the problem, do you think the volume would increase or decrease?

Title: Re:equilibrium challenges
Post by: Donaldson Tan on April 04, 2004, 10:06:35 AM

A(g) + B(g) <-> C(g)
K_c = [C]/[A] = 130

Starting with 0.406mol of C,
let X be mole of C decomposed.
let V be change in volume

Using Law of Equilibrium,
[(0.406-X)/(10.00 + V)]/[X/(10.00 + V)]² = 130
(0.406-X)(10.00+V)/X² = 130
(0.406-X)(10.00+V) = 130X² -(1)

total number of moles of gas in system
= moles of A + moles of B + moles of C
= X + X + (0.406-X)
= 0.406 + X

Change in volume, V
= (0.406 + X)(Molar Volume) - 10.00L
= X(Molar Volume) -(2)

Solve (1) & (2) simultaneously will yield the required answer  ;)