STP stands for Standard Temp. and Pressure. Standard Temp. = 273.15 K Pressure = 1 atm Now, ideal gas equation we know that PV = nRT where, V = volume of gas = 0.475 l R = universal gas constant = .082507 l atm mol-1 K-1
∴ n =[tex] \frac{PV}{RT} [/tex] ∴ n =[tex] \frac{1 X .475}{0.082057X 273.15} [/tex] ∴n = 0.02112 mol
Thus, number of moles of Ar present = 0.02112
But, number of mole = [tex] \frac{wt. of .substance }{At./Mol. Weight} [/tex] In present case, weight of Ar (g) = number of mole of Ar X Atomic Wt. of Ar ∴ weight of Ar = 40 X 0.02112 = 0.8477 g
