# How do partial pressures affect each other?

I'm assuming you're referring to specifically ideal gases. Partial pressure is just the fraction of the total pressure a gas happens to take up in a container. If the partial pressure of ${H}_{2} \left(g\right)$ is 0.2 atm, then it takes up 20% or so of a container with 0.2 atm ${H}_{2} \left(g\right)$ and 0.8 atm of other gases like ${N}_{2} \left(g\right)$ and $A r \left(g\right)$.