The Student Room Group
Uni students - Complete our survey >>
Uni students - Complete our survey >>
Uni students - Complete our survey >>

A Level Chemistry

I really need help with this question, i found it in a book but i cant seem to find the original ester structure.

W is a colourless aliphatic liquid with a relative molecular mass of 123 gmol-1. It says its hydrolysed to produce X and Y. X forms a creamy yellow precipitate with silver nitrate (aq) and y is a secondary alcohol.
Reply 1
Avatar for Pigster
Pigster
20
Original post by oparu
I really need help with this question, i found it in a book but i cant seem to find the original ester structure.

W is a colourless aliphatic liquid with a relative molecular mass of 123 gmol-1. It says its hydrolysed to produce X and Y. X forms a creamy yellow precipitate with silver nitrate (aq) and y is a secondary alcohol.


W is a haloalkane.
X is therefore a certain halide ion.
Y must be a minimum of 3 carbons long, if it is a secondary alcohol.

But 2-bromopropane has a mass of 137!
Yes I was wondering whether you'd given us the full question.

A precipitate with silver nitrate usually implies a halide. A *cream* precipitate implies bromide while a *yellow* precipitate implies iodide.
You mentioned an 'ester', but straightforward esters don't involve halides.

Iodine/Iodide ions have an Ar of (roughly) 127; Bromine/Bromide ions have an Ar of (roughly) 80.
Reply 3
Avatar for IsMo987
IsMo987
12
Hey guys I am starting an online study group for chemistry. We will have a webinar every week and a different person in the group will do it every week.
I was hoping to start from the first topic in year 12
The first webinar is on 18 jan and it’s the first topic mass spectrometry, Ionisation energies etc
It’s for edexcel but every board is welcome as the content is quite similar
If anyone is interested please quote and reply I’ll post the link to the discussion and webinar
Reply 4
Avatar for oparu
oparu
OP
13
Original post by Pigster
W is a haloalkane.
X is therefore a certain halide ion.
Y must be a minimum of 3 carbons long, if it is a secondary alcohol.

But 2-bromopropane has a mass of 137!


Original post by Trumbles
Yes I was wondering whether you'd given us the full question.

A precipitate with silver nitrate usually implies a halide. A *cream* precipitate implies bromide while a *yellow* precipitate implies iodide.
You mentioned an 'ester', but straightforward esters don't involve halides.

Iodine/Iodide ions have an Ar of (roughly) 127; Bromine/Bromide ions have an Ar of (roughly) 80.

Ohh, i get it now thanks. The question didnt say it was ester i automatically assumed that if it hydrolyses to form two compounds, it must be an ester (i was thinking of an acyl chloride and an alcohol but couldnt find the correct molar mass). I completely forgot haloalkanes take part in hydrolysis. Sorry for confusing you, and thanks!
(edited 4 years ago)
Reply 5
Avatar for Pigster
Pigster
20
Original post by oparu
Ohh, i get it now thanks. The question didnt say it was ester i automatically assumed that if it hydrolyses to form two compounds, it must be an ester (i was thinking of an acyl chloride and an alcohol but couldnt find the correct molar mass). I completely forgot haloalkanes take part in hydrolysis. Sorry for confusing you, and thanks!

Still... there is no obviously correct answer. What am I (we) missing?
Reply 6
Avatar for oparu
oparu
OP
13
Original post by Pigster
Still... there is no obviously correct answer. What am I (we) missing?

Is it not 2-bromopropane like you said, CH3CHBrCH3 which has a mass of 123gmol-1? (12*3) + 7 + 80
(edited 4 years ago)
Reply 7
Avatar for Pigster
Pigster
20
Original post by oparu
Is it not 2-bromopropane like you said, CH3CHBrCH3 which has a mass of 123gmol-1? (12*3) + 7 + 80

Curious, I googled bromopropane and it must have returned bromobutane (which is 137).

123 and hence W will be 2-bromopropane.

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you