**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. ** C

**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 H_{2}molecules*i.e*. using 12 H instead of 6 H_{2}) - 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