At 298 K the equilibrium constant for the reaction C _2 H _4(g)+ H _2(g) C _2 H _6(g) is
CHEMISTRY · Single correct · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)
Problem
At 298 K the equilibrium constant for the reaction
C2H4(g)+H2(g)⇌C2H6(g)
is K=9.6. When the temperature is raised to 350 K, the value of the equilibrium constant drops to K=4.1. What is the sign of ΔH∘ for the forward reaction?
(a) ΔH∘>0 (endothermic)
(b) Cannot be determined from the information given
(c) ΔH∘<0 (exothermic)
(d) ΔH∘=0