Question

what is the total pressure of a gas mixture that contains hydrogen at 0.45atm nitrogen at 0.25 atm and argon at 0.60 atm

Answer 1

Add the partial pressures of each gas. The pressures that you listed are called partial pressures. Partial pressure of each gas is the part of the total pressure that is due to that gas.

Answer 2

We find the answer through Dalton's law. The law of partial presure states the total pressure of a gas mixture is the sum of the partial pressure(s). There for we have a formula of:
Pt=P1+P2+P3
Pt=0.45atm + 0.25atm + 0.60atm =
Answer 1.30atm