5.15 Calculate the total pressure in a mixture of 8 g of dioxygen and 4 g of dihydrogen confined in a vessel of 1 dm3 at 27°C. R = 0.083 bar dm3 K1 mol1.

Given,
Mass of dioxide (O2) = 8g
Thus, number of moles of O2 = 832 = 0.25 mole
Mass of dihydrogen (H2) = 4 g
Thus, the number of moles of H2 = 42 = 2 mole
Therefore, total number of moles in the mixture = 0.25 + 2 = 2.25 mole
Given, V = 1 dm3n = 2.25 mol
R = 0.083 bar dm3 K-1 mol-1
T = 27°C = 300 K
Total pressure (p) can be calculated as: pV
= nRT
 p = nRTV
= 225×0.083×3001
= 56.025 bar
Hence, the total pressure of the mixture is 56.025 bar.