How does the room temperature effect the molar mass when conducted in an experiment?

Question

In Chemistry class we conducted an experiment for ideal gas laws with dry ice. My teacher is wondering what would happen to the final molar mass if the room temperature was recorded wrong.

Answer 1

That really depends on how the experiment was performed. I'll assume that you had some dry ice (solid CO2), and you allowed it to sublime into CO2 gas, and collected the gas. Assuming you first measured the mass of the dry ice (or measured it after it sublimed), you would then also know the mass of the gaseous CO2 (assuming you lost none). You would have recorded the temperature, and pressure and then measured the volume of collected gas (assuming you used a known volume flask and corrected for the volume of air). NOTE ALL THE ASSUMPTIONS I've made here since you didn't include them in the question.

PV = nRT

Plug in your values and solve for n (moles)

Molar mass = mass/moles

If the temperature T were recorded incorrectly, that would affect the value obtained for n. If the temperature were recorded HIGHER than the actual temperature, the calculated number of moles would be less than actual and the molar mass would be over-estimated. And, of course, vice versa.