Chemistry

1. 1.

   A compound's infrared spectrum has a strong absorption near 1700 cm^-1. State a likely bond and explain why this alone does not identify the compound.

   [3 marks] · no calculator
2. 2.

   Explain why but-2-ene can have E/Z isomers but but-1-ene cannot.

   [3 marks] · no calculator
3. 3.

   Ignoring OH splitting and assuming fast proton exchange, predict the proton NMR splitting of the CH3 and CH2 groups of ethanol and explain their relative integration.

   [3 marks] · no calculator
4. 4.

   Two compounds have formula C3H6O. One gives a positive Tollens test and the other does not. Identify the aldehyde and ketone possibilities, and give an additional spectral distinction.

   [3 marks] · no calculator
5. 5.

   A C4H8O2 compound shows an ester carbonyl, no broad O-H absorption, and proton NMR signals: singlet at 2.1 ppm (3H), quartet at 4.1 ppm (2H), triplet at 1.3 ppm (3H). Propose a structure and account for each signal.

   [4 marks] · no calculator
6. 6.

   Explain why a racemic mixture of a chiral alcohol has no net optical rotation, and why that observation alone cannot prove a sample is racemic.

   [4 marks] · no calculator

Original, unofficial practice questions from SubjectScout — not official past-paper questions.