What is the molar mass of an unknown gas if 3.7 g of the gas occupies 450 mL at 20.0°C and 2.0 atm? The value of R = 0.0821 L atm mol^-1 K^-1.

Question

Quizplus · Accepted Answer

First, we need to use the Ideal Gas Law: PV = nRT
where P = 2.0 atm, V = 450 mL = 0.45 L, T = 20.0°C + 273 = 293 K, and R = 0.0821 L atm/mol K

Solving for n (the number of moles of gas), we get:

n = PV/RT = (2.0 atm)(0.45 L)/(0.0821 L atm/mol K)(293 K) = 0.0362 mol

Next, we can use the definition of molar mass (M) as the mass of one mole of a substance. In this case, we have 3.7 g of the unknown gas, which corresponds to:

3.7 g / 0.0362 mol = 102 g/mol

Therefore, the molar mass of the unknown gas is approximately 98.9 g/mol, which is closest to choice D.

What Is the Molar Mass of an Unknown Gas If