A 7.75-l flask contains 0.482 g of hydrogen gas and 4.98 g of oxygen gas at 65°c. What is the partial pressure of oxygen in the flask?

0.558 atm

Explanation:

We must first consider that both gases behaves like ideal gases, so we can use the following formula: PV=nRT

Then, we should consider that, whithin a mixture of gases, the total pressure is the sum of the partial pressure of each gas:

P₀ = P₁ + P₂ + ...

P₀ = total pressure

P₁=P₂ = is the partial pressure of each gass

If we can consider that each gas is an ideal gas, then:

P₀ = (nRT/V) ₁ + (nRT/V) ₂ + ...

Considering the molecular mass of O₂:

M O₂ = 32 g/mol

And also:

R = ideal gas constant = 0.082 Lt*atm/K*mol

T = 65°C=338 K

4.98 g O₂ = 0.156 moles O₂

V = 7.75 Lt

Then:

P°O₂=partial pressure of oxygen gas = (0.156x0.082x338) / 7.75

P°O₂ = 0.558 atm