A gas mixture consists of N₂,SO₂,and Ar,where the mole fraction of N₂ is 0.55 and the mole fraction of Ar is 0.25.If the mixture is at STP in a 5.0 L container,how many molecules of SO₂ are present? A) 4.5 × 10²²molecules SO₂ B) 2.7 × 10²² molecules SO₂ C) 3.7 × 10²³ molecules SO₂ D) 1.1 × 10²³ molecules SO₂ E) 9.3 × 10²⁴ molecules SO₂

Question

Quizplus · Accepted Answer

We can first find the mole fraction of SO₂ by subtracting the mole fractions of N₂ and Ar from 1: Mole fraction of SO₂ = 1 - 0.55 - 0.25 = 0.20 Next, we can use the ideal gas law to find the number of molecules of SO₂: PV = nRT where P = 1 atm, V = 5.0 L, n = number of moles, R = 0.0821 L•atm/mol•K (the gas constant), and T = 273 K (STP). Solving for n: n = PV/RT = (1 atm)(5.0 L)/(0.0821 L•atm/mol•K)(273 K) = 0.228 mol Now we can use Avogadro's number (6.022 × 10^23 molecules/mol) to convert from moles to molecules: Number of molecules of SO₂ = (0.20)(0.228 mol)(6.022 × 10^23 molecules/mol) = 2.74 × 10^22 molecules ≈ 2.7 × 10^22 molecules Therefore, the best choice is B.

A Gas Mixture Consists of N2,SO2,and Ar,where the Mole Fraction

A Gas Mixture Consists of N₂,SO₂,and Ar,where the Mole Fraction