At 298 K a chemist studies the three gas-phase reactions summarized in the table below
CHEMISTRY · Multi-part · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)
Problem
At 298 K a chemist studies the three gas-phase reactions summarized in the table below.
Reaction I: SO2(g)+21O2(g)⇌SO3(g); Kp=1.8×1010
Reaction II: Cl2(g)⇌2Cl(g); Kp=4.0×10−7
Reaction III: H2(g)+I2(g)⇌2HI(g); Kp=1.2
Assume each reaction is allowed to reach equilibrium at 298 K starting from stoichiometric amounts of pure reactants (no products present initially).
(a) Rank the three reactions in order of increasing extent of reaction (least product formation to greatest product formation) at equilibrium. Justify your ranking with reference to the given equilibrium constants.
(b) For Reaction II, describe qualitatively how the equilibrium composition compares with the initial composition. Include a discussion at the particulate level of which species will be most abundant and why.
(c) For Reaction III, explain why neither the forward nor the reverse reaction can be considered to "go to completion." Relate your explanation to the numerical value of Kp.