Amixture of oxygen, nitrogen, and hydrogen gases exerts a total pressure of 740 mm hg at 0 degrees celcius. the partial pressure of the oxygen is 200 mm hg and the partial pressure of of the nitrogen is 400 mm hg. what is the partial pressure of the hydrogen gas in this mixture?

Hello!
By law of Dalton’s partial pressure the sum of the partial pressures is the total of all the pressures. So if the total is 740mm Hg then 740=400+200+x so solving for x the unknown pressure we get 740-600=140mm Hg.

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