Practice Problem 6
Calculate the value of Kp for the following reaction at 500oC if the value of Kc for the reaction at this temperature is 0.040.
N2(g) + 3 H2(g) 2 NH3(g)
The value of Kp for a reaction can be calculated from Kc with the following equation.
Kp = Kc x (RT)n
In order to use this equation, we need to know the value of n for the reaction. The balanced equation for this reaction generates two moles of products for every four moles of reactants consumed. The value of n for this reaction is therefore 2 - 4, or -2.
Kp = Kc x (RT)-2
We now use the known value of the ideal gas constant and the temperature in Kelvin to calculate the value of Kp for the reaction at this temperature.
Kp = 0.040 x
= 1.0 x 10-5