PV = nRT (where P = pressure; V = volume; n = number of moles; R = gas constant; T = Temperature)
Moles of H₂ = mass of H₂ ÷ molar mass of H₂
= 6.0 g ÷ 2 g/mol
= 3.0 mol
To get the answer in atmospheres, let's convert C to K
25 °C ≡ 298 K
Now, based on the formula above
P = (nRT) ÷ V
P = (3.0 mol × (0.082 L · atm/mol · K) × 298 K) ÷ 73 L
≈ 1 .004 atm
