At a certain temperature, Kp for the reaction is 789.5, calculate the value of Kp for the following reaction

Question

At a certain temperature, K_p for the reaction,

H₂(g) + Cl₂(g) <=> 2 HCl(g) is 789.5.

Calculate the value of K_p for the reaction,

1/2 H₂(g) + 1/2 Cl₂(g) <=> HCl(g)

the correct answer is: 28.098

please explain!

Answer 1

When you change the coefficients in a reaction (in this case halving them), you must raise the K value to that exponent. So, if you doubled the concentrations, you would square the value of K. In this case, we halved the coefficients, so we must raise the value of K to the 1/2 power, which is the same as taking the square root. Thus, we get (789.5)^1/2 = √789.5 = 28.098