At 300 K, the reaction PH3BCl3(s) <--> PH3(g) + BCl3(g) has a Kc of 6.96*10^-5. What is the value of Kp in this case?

Expert Answers
justaguide eNotes educator| Certified Educator

For an equilibrium reaction, Kc and Kp are related by the relation Kp = Kc*(R*T)^D where D is the number of moles of gaseous products - number of moles of gaseous reactants and R is the gas constant.

Here, Kc = 6.96*10^-5 at 300 K

The value of R is 0.0821; this has to be chosen appropriately for the units that the partial pressure of the gases and the temperature is expressed in.

Kp = Kc*(R*T)^(2 - 0)

=> 6.96*10^-5*(0.0821*300)^2

=> 4.222*10^-2

The value of Kp is equal to 4.222*10^-2