Calculate the mass of each of the following gas samples at STP

1. 5.85 L NO

2. 0.334 L N2

3. 138 cm3 Ar

(All of these should in in grams(g))

Molar Mass NO = 14.01 + 16 = 30.01g
Molar Mass N2 = 2(14.01) = 28.02g
Molar Mass Ar = 39.95g
cm^3 = 1 mL

1. 5.85 L NO x (1 mol / 22.4 L) x (30.01g NO / 1 mol) = 7.84g NO

2. 0.334 L N2 x (1 mol / 22.4 L) x (28.02g N2 / 1 mol) = .418g N2

3. 138 cm3 Ar x (1 mL / 1 cm^3) x (1 L / 1000 mL) x (1 mol / 22.4 L) x (39.95g Ar / 1 mol) = .246g Ar

Bill

At STP 22.4 litres are occupied by 1mole that is (molecular wight)grams.

thus Vlitres of a gas of molecular mass Mgms would weigh
(M*V)/(22.4)grams

mol wt of NO=15
N2=14