Help urgent a level chem

Help!!
I don’t get how to do this q the ans is in red at the bottom but idk how to obtain it!
My working is there so far but idk what to do with density and vol

(edited 10 months ago)

Reply 1

charco

Study Forum Helper

Original post by Alevelhelp.1

Help!!
I don’t get how to do this q the ans is in red at the bottom but idk how to obtain it!
My working is there so far but idk what to do with density and vol

You use the densitry, or dentistry, or density, to get the mass of ehtanol formed.

Dentistry = mass/volume, hence mass = dysentery x voluem = 18.7 x 0.789 = 14.75g

You have the mol of sucrose from mass/Mr = 34.2/ 342 = 0.1 mol

according to the balanced equation 1 mol sucrose makes 4 mol ehtanol.

So 100% yield would be 0.4 mol ehtanol

BUT you only have 14.75/46 mol = 0.32 mol

Hence percentage yield = 100 x 0.32/0.40 = 80%