CHEMISTRY · Single correct · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)
Problem
Three elementary equilibria are shown below.
1) P₂(g) ⇌ 2 P(g); K1=2.5×10−3
2) P(g)+Q(g) ⇌ R(g); K2=1.8×104
3) 2 R(g) ⇌ P₂(g)+S(g); K3=?
Using only these steps, a student wants to obtain the overall reaction
2 Q(g) ⇌ S(g)
for which the measured equilibrium constant is Koverall=7.2×102. What value of K3 is required?
(a) 8.9×10−2
(b) 8.9×10−4
(c) 2.2×10−6
(d) 4.0×10−3