23.1 L of an unknown gas has a mass of 28.85 g at STP What is the identity of the unknown gas?

23.1 L of nitrogen has a mass of 28.85 g at STP.

An unknown gas occupies 23.1 L at STP. We will calculate the moles of the gas, considering that 1 mole of an ideal gas occupies 22.4 L at STP.

1.03 moles of the unknown gas have a mass of 28.85 g. The molar mass of the gas is:

A gas with a molar mass of 28.0 g/mol is likely to be nitrogen gas.

23.1 L of nitrogen has a mass of 28.85 g at STP.

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The unknown gas : N₂

Given

Volume : 23.1 L

Mass : 28.85 g

Required

The identity of the unknown gas

Solution

Conditions at T 0 ° C and P 1 atm are stated by STP (Standard Temperature and Pressure). At STP, Vm is 22.4 liters / mol

So mol for The unknown gas :

= 23.1 L : 22.4 L

= 1.0313

The molar mass of unknown gas :

= mass : mol

= 28.85 g : 1.0313

= 27.974 g/mol≈ 28 g/mol