The vapor pressure of diethyl ether is 463.57 mm Hg at 25 degrees celsius. How many grams of aspirin C9H8O4, a non volatile nonelectrolyte (mw=180.1g/mol), must be added to 216.7g of ether to reduce the vapor pressure to 453.74 mm Hg.

Question

Ether=74.12g/mol

This question is similar to the other one that I posted. Do I first have to convert to moles for both?

Answer 1

Yes for ether. You don't know grams aspirin so you can't calculate moles aspirin.
Subtract normal vp ether - vp ether desired, plug into
pether = Xether*Po ether and solve for Xether.
Then find Xaspirin (it's 1.000 - Xether) and from that grams aspirin.
It's just the reverse of what you did in the other problem.

Answer 2

so I did 463.57 - 453.74 = 7.600

Then I found moles of ether to be 4.0313.

I do not understand the next step to find Xether.