# Defining equilibrium position vs equilbrium constant

My chemistry textbook says that $K_{p}$ indicates the equilibrium position. It then says that $kp$ will not change if pressure is increased, but it also says that the position of equilibrium does change if pressure is increased.

Let me restate that: $K_{p}$ tells you the equilibrium position. Increasing pressure does not change $K_p$ (indicating the equilibrium position does not change) but does change the equilibrium position. This is clearly a contradiction, so how should I properly define equilibrium position and equilibrium constants? I've never really had a clear understanding of what equilibrium position means.

• Mind your Ps and Qs -- or rather, mind your ks and Ks. A lowercase 'k' is usually used to denote a rate contstant, while an uppercase K is an equilibrium constant. Oct 26, 2017 at 19:28

Partial pressures of reactants and products factor into the equilibrium constant $K_{\mathrm{p}}$. If you increase the partial pressure of a gas that is not participating in the equilibrium, none of the other partial pressures change, so the equilibrium is unaffected, but the total pressure will change. Thus, depending on the circumstances, changing the total pressure may or may not change the position of equilibrium.