For the gaseous reaction at 450 °C

CHEMISTRY · Subjective · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)

Problem

For the gaseous reaction H2(g)+I2(g)⇌2HI(g)\text{H}_2(g)+\text{I}_2(g)\rightleftharpoons 2\text{HI}(g) at 450 °C, two separate trials are begun with different initial reactant concentrations. Trial 1 starts with [H2]=[I2]=0.50 M[\text{H}_2]=[\text{I}_2]=0.50\,\text{M}, while Trial 2 starts with [H2]=[I2]=1.00 M[\text{H}_2]=[\text{I}_2]=1.00\,\text{M}. After equilibrium is reached in each trial, the ratio [HI]2[H2][I2]\dfrac{[\text{HI}]^2}{[\text{H}_2][\text{I}_2]} is found to have the same numerical value. In one or two sentences, explain why this ratio is identical for both trials even though the initial concentrations differ.

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