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Question

1.) An unknown gas with a mass of 11.003 g and a volume of 6.630 L has a pressure of 760.00 torr at 37°C. Find its molar mass

2.) What is the unknown gas in the first problem?

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Answer 1

1). Since we have the mass (11.003 g), and are asked for the molar mass, that means we MUST find the number of moles because molar mass = g / moles. So, let's find the number of moles of gas:

PV = nRT (change 760 torr to 1 atm)

n = PV/RT = ( 1 atm)(6.63 L) / (0.0821 Latm/Kmol)(310K) = 0.2605 moles

molar mass = 11.003 g / 0.2605 moles = 42.24 g/mol

2). Unfair question. There could be many, many gases that have this molar mass. One possible guess would be PROPENE (C₃H₆)