Question

A 2.60-g sample of white solid was vaporized in a 345-mL vessel. If the vapor has a pressure of 985 mmHg at 152°C, what is the molecular mass of the solid?

Answer 1

PV = nRT

You know P. Convert that to atm. 985mm/760 = ?
You know V. Convert that to L. 345 mL/1000 = ?
Solve for n = mols
You know R = 0.08205 L*atm/mol*K
You know T = 152 C. Convert to K. K = 152 C + 273 = ? K
After you know n, then n = grams/molar mass. You know g and n. solve for molar mass = ?
Post your work if you get stuck.