The equilibrium constant for the formation of phosphorus pentachloride is 1.9. If the partial pressure of each gas is 0.5 atm, will the reaction (as written) proceed forward or backward to reach equilibrium?
PCl3(g) + Cl2(g) PCl5(g)
A. Forward, because K is greater than Q
B. Backward, because K is less than Q
C. Forward, because K is less than Q
D. Backward, because K is greater than Q
2 answers
I know that the answer is not A... can anyone help me any further?
Is that Kc or Kp? I will assume it is Kp since the pressures are given but the problem is worked the same way for each (Kp is used with partial pressures; Kc with concentrations in mols/L)
K = 1.9
Q = p(PCl5)/p(PCl3)*p(Cl2)
Q = (0.5)/(0.5)(0.5) = 2
Looking at Q = 2, that is > Kp of 1.9. That means the numerator is too large and the denominator too small. So the reaction must shift to the left (backwards).
K = 1.9
Q = p(PCl5)/p(PCl3)*p(Cl2)
Q = (0.5)/(0.5)(0.5) = 2
Looking at Q = 2, that is > Kp of 1.9. That means the numerator is too large and the denominator too small. So the reaction must shift to the left (backwards).
4 answers