7.5 Find out the value of Kc for each of the following equilibria from the value of Kp:

(i) 2NOCl (g) 2NO (g) + Cl2 (g); Kp= 1.8 × 10–2 at 500 K

(ii) CaCO3 (s) CaO(s) + CO2(g); Kp= 167 at 1073 K

The relation between Kp and Kc is given as:

Kp=KcRTna Here,n=3-2=1R=0.0831 barLmol-1K-1T=500 KKp=1.8×10-2Now,Kp=KcRTn1.8×10-2=Kc0.0831×5001Kc=1.8×10-20.0831×500         =4.33×10-4approximatelyb  Here, n=2-1=1R=0.0831 barLmol-1K-1T=1073 KKp=KcRTn167=Kc0.0831×10731Kc=1670.0831×1073         =1.87approximately