Question

A sample of an unknown compound is vaporized at 130°C . The gas produced has a volume of 1280mL at a pressure of 1.00 atm and it weighs 4.03g

Assuming the gas behaves as an ideal gas under these conditions, calculate the molar mass of the compound. Round your answer to 3 significant digits.

Answer 1

This is an ideal gas law question. It uses the ideal gas law equation, PV =nRT.
P = pressure, V = volume, n = moles, R is the constant, and T is temperature in kelvin. The temperature needs to be converted Kevin first. To convert from Celsius to Kevin, you add 273, meaning that the temp in Kevin is 403K. Then plug all the info into the equation to solve for moles.
(1.00atm)(1.280L)=n(0.0821)(403K)
n = 0.0387moles

To find molar mass, divide mass by moles.

4.03g / 0.0387moles = 104.17g/mol

104g/mol rounded to three significant digits