An equilibrium mixture for the reaction N _2(g)+ O _2(g) ; ;2 , NO (g) is sealed in a…
CHEMISTRY · Single correct · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)
Problem
An equilibrium mixture for the reaction
N2(g)+O2(g)⇌2NO(g)
is sealed in a rigid vessel at 800\,K. After equilibrium is established, 2.0\,atm of helium is injected and the temperature is allowed to return to 800\,K. Which statement best describes the effect of the added helium on the value of Kp for the reaction?
(a) Kp increases because the total pressure of the system has increased, so every partial-pressure term is larger.
(b) Kp increases because increasing pressure favors the side with more gas molecules, raising the value of Kp.
(c) Kp remains unchanged because it depends only on temperature, not on the presence of inert gases.
(d) Kp decreases because the partial pressures of the reactants decrease when helium is added at constant volume.