A gas sample contains 4.0 g of and 2.0 g of He.What is the volume of the sample at STP?
A)130 L
B)11 L
C)17 L
D)30.L
E)5.6 L

Question

A gas sample contains 4.0 g of  and 2.0 g of He.What is the volume of the sample at STP?
A)130 L 
B)11 L 
C)17 L 
D)30.L 
E)5.6 L

Quizplus · Accepted Answer

Using the ideal gas law, PV = nRT, we can find the number of moles of each gas:
n(He) = 2.0 g / 4.00 g/mol = 0.500 mol
n(CO2) = 4.0 g / 44.01 g/mol = 0.0910 mol
Total number of moles = 0.500 mol + 0.0910 mol = 0.591 mol
At STP, T = 273 K and P = 1 atm. Rearranging the ideal gas law equation to solve for V:
V = (nRT) / P = [(0.591 mol)(0.0821 L•atm/mol•K)(273 K)] / (1 atm) = 16.7 L ≈ 17 L
Therefore, the best choice is C.

A Gas Sample Contains 4