Two students are given a homework assignment that involves analysing a set of spectra and identifying an unknown compound - VCE - SSCE Chemistry - Question 7 - 2021 - Paper 1
Question 7
Two students are given a homework assignment that involves analysing a set of spectra and identifying an unknown compound. The unknown compound is one of the molecul... show full transcript
Worked Solution & Example Answer:Two students are given a homework assignment that involves analysing a set of spectra and identifying an unknown compound - VCE - SSCE Chemistry - Question 7 - 2021 - Paper 1
Step 1
Eliminate Compounds P, Q, and S
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Answer
Analyzing the IR spectrum shows that:
Compound P lacks an -O-H group and thus can be eliminated.
Compound Q contains an -O-H group, but does not indicate a broad -O-H absorption around 2500 cm^-1. Thus, this can also be eliminated.
Compound S also does not have an -O-H group, leading to its elimination as well.
Step 2
Identify Compound Q
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Answer
Compound Q must possess the -O-H group, as shown by the clear absorption around 3500 cm^-1 in the IR spectrum. Furthermore, it is likely to be a carboxylic acid due to the expected strong absorption in the range of 2500 cm^-1 to 3500 cm^-1.
Step 3
Analyze the NMR spectrum
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Answer
The peaks in the 13C NMR spectrum provide additional insights. The presence of peaks in specific regions correlating with the identified structure of Q supports its identification as the unknown compound.
