Homework Help: Chemistry

Posted by Kathy on Monday, September 5, 2011 at 3:36pm.

A mixture of He and CO2 in a flask at 45.0°C exerts a pressure of 955 torr. All of the CO2 is removed and is found to weigh 0.879 g. The pressure drops to 555 torr after the removal of CO2. What is the mass of He?

Chemistry - DrBob222, Monday, September 5, 2011 at 10:07pm
You don't have a volume listed but you can calculate it.
PCO2 = 955-555 = ?? mm Hg
PHe = 555 mm Hg.
Use PCO2 and PV = nRT to solve for V. Then use PV = nRT and PHe to solve for nHe, then n He= grams/molar mass.

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