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.
Isomer P:
1. Identify the isomer(s) that would react when warmed with acidified potassium dichromate(VI).
S... 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 isomer(s) that would react are Q, R, S, and T. The expected observation is a change in color of the solution to green, indicating the reduction of potassium dichromate(VI).
Step 2
Identify the isomer(s) that would react with Tollen's 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 with Tollen's reagent is T. The expected observation is the formation of a silver mirror on the inner surface of 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 are P, Q, R, and 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 the production of bubbles of carbon dioxide gas, which indicate an acid-base reaction.
Step 5
Give a reason why the mixture is poured into sodium hydrogencarbonate 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 hydrogencarbonate solution to neutralize any unreacted acid present in the mixture.
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 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
To distinguish between isomers S and T using IR spectra, one can look for specific absorbance peaks. Isomer S will have a broad O-H stretch peak around 3230-3550 cm⁻¹ due to alcohol or phenol groups, while T may show a C=O stretch around 1680-1750 cm⁻¹ indicating a carbonyl group. Additionally, the fingerprint region below 1500 cm⁻¹ can provide unique spectral features 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
Mass spectrometry using electrospray ionisation is not suitable because all isomers can have the same molecular ion M ext{Z} peak, making it difficult to differentiate among them based solely on mass.
