CHEMISTRY COMMUNITY

Can someone give the definition of partial pressures and why its important to use partial pressures for gases and concentration for everything else?

Partial Pressure is basically the pressure exerted by one gas in a mixture of multiple in a specific volume. You don't have to use partial pressure for gases per se, but gases are often measured by their pressure instead of their concentration. Also, you can't measure pressure for other states thus you use concentration as it is more convenient.

Suppose we have a mixture of gases in a box. The total pressure of the mixture agains the walls of the box is equal to the pressure exerted by each individual gas. The pressure exerted by each individual gas is the partial pressure.

We use partial pressures for gases because I think because the partial pressure of a gas is proportional to the concentration, and so it allows us to calculate a k-value that is different from Kc, yet gives the same information as Kc.