Synoptic chemistry question help

Ive been attempting this question for the past 20minutes and just cant work it out, so I have come here to ask the wise ones on the student room to help me. The question is 3a) from the June 2005 Edexcel synoptic paper:

Carboxylic acid reacts reversibly with alcohols, in the presence of a catalyst to form an ester and water.

When 24.8g of ethane-1,2-diol, HOCH2CH2OH, was mixed with 66.0g of ethanoic acid, CH3COOH, in the presence of a catalyst, equilibrium was reached after 80.0% of the ethane-1,2-diol had reacted. The total volume at equilbrium was 90.0cm3.

HOCH2CH2OH + 2CH3COOH <-- CH3COOCH2CH2OOCCH3 + 2H2O
-->

Write the expression for the equilbirum constant Kc and calculate its value. You should make clear what units if any there are for Kc.

Ive also attached the mark scheme and my answer for this question so if anyone can explain how the hell you're supposed to work out the equilibrium moles for the ethanoic acid I would appreciate it A LOT! Thank you in advance :smile:

maoam x

P.S sorry for the essay

synoptic chem question.doc23.6KB

Reply 1

Robusty

hey, i've done this paper, now i'll just need to find it for u, hang on

Reply 2

maoam

Thank you robusty!

maoam x

Reply 3

ShAdOw-G

Enclosed is how to work it out, along with a method I would use. Just shout if you dont get anything. Peace

ANSWER.doc28.7KB

Reply 4

maoam

Thank you soooooooooooo much christ I can be such a knob sometimes, I was doubling the wrong number, I only read the first line and then it clicked. but thank you so much for your help. :smile:

maoam x

Reply 5

ShAdOw-G

no worries

Reply 6

Robusty