To evaluate Kp for the reaction at 450°C, we need to use the relationship between Kp and Kc, which involves the gas constant, R, and the temperature, T.
The equation relating Kp and Kc is:
Kp = Kc * (RT)^(Δn)
Where:
- Kp is the equilibrium constant in terms of partial pressures.
- Kc is the equilibrium constant in terms of molar concentrations.
- R is the gas constant (R = 0.0821 L·atm/(mol·K)).
- T is the temperature in Kelvin.
- Δn is the difference in the total moles of gaseous products and reactants.
In the given reaction: PCl5(g) ⇌ PCl3(g) + Cl2(g), we can see that there is no change in the total moles of gaseous products and reactants (Δn = 0).
Therefore, Δn = 0, and the term (RT)^(Δn) becomes (RT)^0, which simplifies to 1.
Hence, the equation becomes:
Kp = Kc * 1
Therefore, Kp is equal to Kc.
In this case, Kp = 0.040 at 450°C.