chemisty
posted by unknown on .
To identify a diatomic gas (X2), a researcher carried out the following experiment: She weighed an empty 1.00L bulb, then filled it with the gas at 1.10 atm and 23.0 C and weighed it again. The difference in mass was 1.27 g . Identify the gas.

PV=nRT.
You know P, V, R and T. Calculate n = # mols of the gas.
Then you know mols = grams/molar mass.
You know mols and grams, calculate molar mass. Molar mass divided by 2 (since it is diatomic) = atomic mass. Look that up on the periodic table. Post your work if you get stuck. 
C2H4

Rearrange the equation so it looks like n=PV/RT
First change 23C to Kelvin= 296 Kelvin
Plug in what you have:
n= (1.10atm)(1.00L)/(0.08206)(296)
n=0.045 that is the number of moles you have. But it doesn't tell you what type of element it is. So you need to find out the molar mass of the element.
take what the equation gives you for grams
1.27 and divide that by the number of moles you have
1.27grams/0.045mole = 28.22g/mol
But since it is a diatomic gas, that means you have to divide it by two to see the mass of each individual molecule.
28.22/2= 14.11
Look on the periodic table for the element with a mass of 14.11 it is Nitrogen.
So your answer would be N2