Ideal gas law: Which contains more moles of material: 80 grams of helium gas (He, having atomic weight 4.0 g/mol) or 400 grams of argon gas (Ar, having atomic weight 40 g/mol)?
A) helium
B) argon
C) Both contain the same number of moles.

Question

Quizplus · Accepted Answer

The number of moles of a gas can be calculated using the ideal gas law: PV=nRT, where P is pressure, V is volume, n is the number of moles, R is the molar gas constant, and T is temperature. Since both gases are at the same temperature and pressure, we can use the equation to calculate the number of moles of each gas.

For helium: 
n = (m/M) = (80 g)/(4.0 g/mol) = 20 mol

For argon: 
n = (m/M) = (400 g)/(40 g/mol) = 10 mol

Therefore, 80 grams of helium contains more moles of material compared to 400 grams of argon.

Ideal Gas Law: Which Contains More Moles of Material: 80