Please help with A level chem question please!Watch
The results of the tests are shown below.
Test Br2(aq) Na2CO3(aq) Observation decolourised effervescence
What is the minimum number of C atoms in Y?
An aromatic compound with a carbon count of seven, which satisfies those tests, would have to be one which contains a phenolic group and a -COOH group; the phenolic group can allow the benzene ring to decolourise bromine water, and the -COOH group can effervesce with the carbonate.
(Extra information - this compound is salicylic acid).
It cannot be A. An aromatic compound with a carbon count of six, which can decolourise bromine water, would be phenol; however, phenols don't react with carbonates, so there would be no effervescence. Hence, the -COOH group is necessary for effervescence, and so this will bring the carbon count up to seven.
C and D would simply have excessive carbon atoms.