Question

1.45 g of an unknown gas at 53 °C and 1.10 atm is stored in a 1.85-L flask.

What is the density of the gas


what is the molar mass of the gas

Answer 1

The problem doesn't say the conditions you want for the density; i.e., is that density at 53 C and 1.10 atm or density at STP. I will assume you want it at STP. Therefore, we must correct the volume from 1.85 L to the volume at STP. So T goes from 326 K (273 + 53) to 273 K and pressure goes from 1.10 atm to 1.00 atm.
1.85 L x (273/326) x (1.10/1.00) = about 1.70 L but you should go through that yourself.
Then density = 1.45 g/1.70 = ?

Then density of a gas at STP = molar mass/22.4 L. You know density at STP, solve for molar mass.