WAEC - Chemistry (2014 - No. 17)
The mass of 800cm3 of gas Q at s.t.p. is 1.0g. What is the molar mass of Q? [Avogadros constant = 22.4dm3 mol-1`]
18.0 gmol-1
22,4gmol-1
28.0gmol-1
36.0 gmol-1
Explicació
Imole Q occupies 22400 cm3
x mole occupies 800 cm3
x = \(\frac{800 x 1}{22400}\)
= 0.036mol
Molar mass = Mass ÷ Mole
= 1 ÷ 0.036
Molar mass ≈ 28 g/mol