A gas sample with volume 1.00 L contains 0.50 g of gas at STP. What is its density in g/L?

A gas sample with volume 1.00 L contains 0.50 g of gas at STP. What is its density in g/L?

• A. 0.25 g/L
• B. 0.75 g/L
• C. 0.50 g/L
• D. 1.00 g/L

Answer: (C)

Density is mass per unit volume. Here you have 0.50 g of gas in 1.00 L, so the density is 0.50 g / 1.00 L = 0.50 g/L. At STP, that density corresponds to a molar mass of about 11.2 g/mol if you relate it to the 22.4 L per mole, but the question is answered directly by mass over volume.

Density is mass per unit volume. Here you have 0.50 g of gas in 1.00 L, so the density is 0.50 g / 1.00 L = 0.50 g/L. At STP, that density corresponds to a molar mass of about 11.2 g/mol if you relate it to the 22.4 L per mole, but the question is answered directly by mass over volume.