WAEC SSCE - Chemistry - 1989 (Objective)

Question 1 Report

If 200cm ³ of a gas at s.t.p. has a mass of 0.268g, what is its molar mass? (Molar volume of a gas at s.t.p. = 22.4 dm³)

300g

200g

150g

30g Correct answer

15g

Answer Details

The molar mass of a gas can be calculated using the following formula: molar mass = mass ÷ number of moles At standard temperature and pressure (STP), the molar volume of a gas is 22.4 dm³, which is equivalent to 22,400 cm³. Therefore, the number of moles of the gas can be calculated as follows: number of moles = volume of gas at STP ÷ molar volume of gas at STP number of moles = 200 cm³ ÷ 22,400 cm³/mol number of moles = 0.00893 mol Now, we can use the formula for molar mass to find the answer: molar mass = mass ÷ number of moles molar mass = 0.268 g ÷ 0.00893 mol molar mass = 30.03 g/mol Therefore, the molar mass of the gas is approximately 30 g/mol. The correct answer is.

Read lesson note on Kinetic Theory Of Matter And Gas Laws (JAMB)






Press & Hold to Drag Around
Click Here to Close