Calculate the total moles of gas present = 0.4 + 2.5 = 2.9mol
Calculate the total gas pressure assuming ideal gas behaviour: PV = nRT P = n x R x T ÷ V n = 2.9mol R = 8.314 T = 25oC = 25 + 273 = 298K V = 10L P = 2.9 x 8.314 x 298 ÷ 10 = 718kPa (7atm)
Partial pressure of nitrogen = n(N2) ÷ n(total) x total pressure Partial pressure of nitrogen = 0.4 ÷ 2.9 x 718kpa = 99kPa (0.9atm)
Partial pressure of helium = n(He) ÷ n(total) x total pressure Partial pressure of helium = 2.5 ÷ 2.9 x 718 = 619kPa (6.1atm)
At 15oC, 25mL of neon at 101.3kPa (1atm) pressure and 75mL of helium at 70.9kPa (0.7atm) pressure are both expanded into a 1L sealed flask. Calculate the partial pressure of each gas and the total pressure of the gas mixture.
Since the temperature and moles of each gas is constant, the pressure exerted by each gas is inversely proportional to its volume (Boyle's Law). PiVi = PfVf Pf = PiVi ÷ Vf
Partial pressure Neon = 101.3kPa x 25 x 10-3L ÷ 1L = 2.5kPa
Partial pressure Helium = 70.9kPa x 75 x 10-3L ÷ 1L = 5.3kPa