The molecular weight of a gas is ________ g/mol if 3.5 g of the gas occupies 2.1 L at STP. A)41 B)5.5 × 10³ C)37 D)4.6 × 10² E)2.7 × 10^-2

Question

Quizplus · Accepted Answer

Using the ideal gas law, we can calculate the number of moles of gas present:

PV = nRT

where P = 1 atm, V = 2.1 L, T = 273 K, and R = 0.0821 L*atm/(mol*K)

n = PV/RT = (1 atm)*(2.1 L)/(0.0821 L*atm/K*mol)*(273 K) = 0.0897 mol

Now we can calculate the molecular weight (MW) using the given mass and number of moles:

MW = mass/number of moles = 3.5 g/0.0897 mol = 39 g/mol (rounded to two significant figures)

The closest answer choice is C, which is 37 g/mol.

The Molecular Weight of a Gas Is ________ G/mol If