At 700 K, the equilibrium constant for the gas‐phase reaction H (g) + I (g) ⇌ 2 HI(g)…
CHEMISTRY · Multi-part · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)
Problem
At 700 K, the equilibrium constant for the gas‐phase reaction
H2(g) + I2(g) ⇌ 2 HI(g) is Kc=54.
A reaction mixture at 700 K in a 2.00 L container contains the following amounts before equilibrium is established:
• H2: 0.400 mol
• I2: 0.400 mol
• HI: 0.200 mol
(a) Write the expression for the reaction quotient Qc.
(b) Calculate the numerical value of Qc for the initial mixture. Show all work and include units where appropriate.
(c) By comparing Qc with Kc, indicate the direction in which the reaction must proceed to reach equilibrium. Justify your answer quantitatively.