Answer to Question #19872 in Inorganic Chemistry for Brittany

Question

A mix of O, N, and Ar has total pressure of 1.5 atm. The weights of the gases in the mix are 1.42g, 1.00g, and .50g. Calculate partial pressure of each gas; if volume of mix is 2L, what's the temp of the gas? At this temp, what's the root mean square speed of the N molecules?

Answer 1

P_i =x_i*P
x_i = n_i/n
n(O₂) = 1.42 g / 32 g/mol = 0.044 mol
n(N₂) = 1.00 g / 28 g/mol = 0.0357 mol
n(Ar) = 50 g / 40 g/mol = 1.25 mol
x_i(O₂) = 0.044/(0.044 + 0.0357+1.25) = 0.044/1.33 = 0.033
x_i(N2) = 0.0357/1.33 = 0.027
x_i (Ar) = 1.25 / 1.33 =0.94
P_i(O2) = 0.033*1.5= 0.0495 atm
P_i(N2) = 0.027 * 1.5 = 0.0405 atm
P (Ar) = 0.94*1.5 = 1.41 atm
PV = nRT
T = PV/nR
T = 15450 Pa * 0.002 m3 / 1.33 mol *8.314 = 2.79 K