A small glass measuring cylinder of oil is placed inside a freezer where the temperature is -18°C. Fig. 9.1 shows how the temperature of the oil varies with time t. [Figure 9.1] Fig. 9.1 shows that it takes 700s for the temperature to decrease from 20°C to 10°C but that it takes 1900s to decrease from 0°C to -10°C.

1. (a)Suggest why these times are different.[3]
2. (b)Explain what happens to the molecules of the oil and what happens to the level of the oil in the glass measuring cylinder as the temperature decreases from 20°C to 0°C.[3]
3. (c)(i)Determine the melting point of the oil.[1]
4. (c)(ii)Explain, in terms of molecules, why the temperature of the oil does not change between t = 3600 s and t = 10800 s.[3]
5. (d)(i)There is 45g of oil in the glass measuring cylinder and the specific latent heat of fusion (melting) of the oil is 5.7 × 10⁴ J/kg. Calculate: the energy transferred from the oil between t = 3600s and t = 10800 s[2]
6. (d)(ii)the average rate at which energy is transferred from the oil between t = 3600s and t = 10800 s.[1]
7. (e)The graph in Fig. 9.1 is steeper before the horizontal section than it is after. Use this observation to compare the specific heat capacity of oil in the liquid and solid states and explain your reasoning.[2]

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