This question is about the structural isomers shown - AQA - A-Level Chemistry - Question 3 - 2020 - Paper 2
Question 3
This question is about the structural isomers shown.
Identify the isomer(s) that would react when warmed with acidified potassium dichromate(VI).
State the expecte... show full transcript
Worked Solution & Example Answer:This question is about the structural isomers shown - AQA - A-Level Chemistry - Question 3 - 2020 - Paper 2
Step 1
Identify the isomer(s) that would react when warmed with acidified potassium dichromate(VI).
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The isomers that would react are Q, R, S, and T. The expected observation is that the orange solution will turn green.
Step 2
Identify the isomer(s) that would react with Tollens' reagent.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The isomer that would react is T. The expected observation is the formation of a silver mirror on the test tube.
Step 3
Identify the isomer(s) that would react with ethanolic acid.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The isomer(s) that would react with ethanolic acid is S.
Step 4
Suggest a simple way to detect if the ethanolic acid reacts with each isomer.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
A simple way to detect the reaction is to observe if there is sweet smelling liquid produced.
Step 5
Give a reason why the mixture is poured into sodium hydrogen carbonate solution.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The mixture is poured into sodium hydrogen carbonate to neutralize any remaining acid and to identify any carbon dioxide produced.
Step 6
State the type of structural isomerism shown by isomers P, Q, R and S.
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The type of structural isomerism shown by isomers P, Q, R, and S is positional isomerism.
Step 7
Describe fully how infrared spectra can be used to distinguish between isomers S, R and T.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Isomer R and S will show an OH alcohol peak in the range of 3230-3550 cm⁻¹. Isomer T will show a C=O peak around 1680-1750 cm⁻¹. S is unique because it will have a fingerprint region below 1500 cm⁻¹ which can be compared to a database or known spectra for identification.
Step 8
State why mass spectrometry using electrospray ionisation is not a suitable method to distinguish between the isomers.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
All the isomers would have the same molecular ion Mz peak since they have the same molecular formula.
