Photo AI
Unknown samples of three carboxylic acids, labelled X, Y and Z, are analysed to determine their identities - HSC - SSCE Chemistry - Question 35 - 2024 - Paper 1
Question 35
Unknown samples of three carboxylic acids, labelled X, Y and Z, are analysed to determine their identities. Both Y and Z react rapidly with bromine in the absence o... show full transcript
Worked Solution & Example Answer:Unknown samples of three carboxylic acids, labelled X, Y and Z, are analysed to determine their identities - HSC - SSCE Chemistry - Question 35 - 2024 - Paper 1
Step 1
Identify structures of acids X, Y and Z
Answer
X does not undergo an addition reaction with Br₂ or a hydration reaction, indicating it does not possess a double bond. Thus, the only viable structure for X is Structure 2.
Y and Z are capable of containing at least one double bond due to the bromine and hydration reactions. Since a 0.100 g sample of Y reacts with the same amount of Br₂ as a 0.200 g sample of Z, we can determine that Y must have double the molar mass of Z.
Only one product is formed from the hydration of Z so Z must be symmetrical around the carbon and Y is non-symmetrical.
The equal volumes of Y and Z in the titration indicate that Y is double the molar mass of Y and being a diprotic acid, thus, Structure 1 is Y and Structure 3 is Z.