Copper(II) nitrate decomposes on heating. The reaction is endothermic.

2Cu(NO₃)₂(s) → 2CuO(s) + 4NO₂(g) + O₂(g)

a. Draw an enthalpy level diagram (reaction profile diagram) for this reaction.

b. Draw an enthalpy cycle diagram to calculate the standard enthalpy change for this reaction, using enthalpy changes of formation.

c. Calculate the enthalpy change for this reaction using the following enthalpy changes of formation.

ΔH^Q_f [Cu(NO₃)₂(s)] = –302.9 kJ mol^–1

ΔH^Q_f [CuO(s)] = –157.3 kJ mol^–1

ΔH^Q_f[NO₂(g)] = +33.2 kJ mo^l–1

d. Copper(II) sulfate is soluble in water. A student dissolved 25.0 g of copper(II) sulfate in 100 cm³ of water in a polystyrene beaker stirring all the time. The temperature of the water fell by 2.9^°C.
i. Calculate the enthalpy change of solution of copper(II) sulfate. (specific heat capacity of  water = 4.18 J g^–1°C^–1; relative molecular mass of copper(II) sulfate = 249.7 g mol^–1)  
ii. Suggest one source of error in this experiment and explain how the error affects the results.