In this article we examine three approaches, leading to different conclusions, for answering the question "Does the addition of inert gases at constant volume and temperature modify the state of equilibrium?" In the first approach, the answer is yes as a result of a common students' alternative conception; the second approach, valid only for ideal mixtures of gases, leads to a negative response, and in the third approach the answer is "a little" obtained from a more universal explanation. This last approach, ignored even in advanced chemistry textbooks, is valid for real mixtures of gases and the effects start to become verifiable at moderate pressures. Le Châtelier's principle application to pressure variations is explored in the context of the results from the different approaches.
Supplement
Detailed quantitative processes and equilibrium compositions
Our Secondary School editors work hard to distill all the JCE materials to produce a fraction of particular interest to high school teachers. We call it CLIC.
In recent years we have worked hard to better match our advertisers with our readers. When shopping for chemistry education materials, visit our advertisers' WWW sites first.
Take JCE along on your outreach missions. Copies of the Journal, guest access to JCE Online, our publications catalog, and more are available for your participants.