Part 6: THERMODYNAMICS

This should have been a reasonably straight forward calculation, but care needs to be taken to get the right structures and the right molecular formula, then do the math correctly.

a. C₆H₁₀ + 17/2 O₂ --> 6 CO₂ + 5 H₂O (1 mark)

b. The caculation is shown on the figure below (2 marks, 1 each)

c. (4 marks)

d. Possible examples of weaker C-H would include a tertiary allylic C-H, or a doubly allylic system. For possible examples, see below: (2 marks)

e. Possible examples of stronger C-H would include a sp C-H in a terminal alkyne or a primary vinyl C-H. For possible examples, see below: (2 marks)

f. If there are 3 different monochlorination products, the starting material requires 3 different types of sp3 C-H. Two possible answers are shown below: (2 marks)

Common errors:

• incorrect coefficients in the balanced equation
• wrong sign in calculated values
• calculation error (e.g. based on number of H atoms rather than H₂ molecules i.e. using 12 H instead of 6 H₂)
• drawing isomers that did not fit the required molecular formula
• not labelling the correct bonds
• overlooking the impact of non-equivalent resonance structures on radical chlorination