A 0.334 g sample of an unknown halogen occupies 109 mL at 398 K and 1.43 bar. What is the identity of the halogen?

Question

Quizplus · Accepted Answer

Using the ideal gas law (PV = nRT), we can calculate the number of moles of the unknown halogen:

n = PV/RT = (1.43 bar * 0.109 L)/(0.08314 L bar mol^-1 K^-1 * 398 K) = 0.00522 mol

Next, we can calculate the molar mass of the unknown halogen:

molar mass = sample mass/number of moles = 0.334 g/0.00522 mol = 64.0 g/mol

Comparing this molar mass to the molar masses of the elements in the answer choices, we see that only chlorine (Cl) has a molar mass close to 64.0 g/mol (actual molar mass = 35.5 g/mol). Therefore, the identity of the unknown halogen is most likely chlorine.

A 0334 G Sample of an Unknown Halogen Occupies 109 ML