Sucrose is a white crystalline solid, C12H22O11. In reaction Z, sucrose reacts with water in the presence of a catalyst, aqueous hydrochloric acid, to form glucose and fructose. glucose [Figure: glucose structure] fructose [Figure: fructose structure] reaction Z

1. (a)(i)Suggest a name for the reaction that occurs when sucrose reacts with water to form glucose and fructose.[1]
2. (a)(ii)If no catalyst is added in reaction Z, the reaction is very slow. Label the Boltzmann distribution to show the effect of adding a catalyst to the sample of sucrose and water molecules at constant temperature. [Figure: Boltzmann distribution graph] Explain your labelled diagram.[3]
3. (b)Both fructose and glucose contain chiral centres.
4. (b)(i)Explain what is meant by the term chiral centre.[1]
5. (b)(ii)On the diagram of the fructose molecule, label all the chiral centres with an asterisk (*).[1]
6. (b)(iii)Determine the empirical formula of fructose.[1]
7. (c)(i)Explain what is meant by the term enthalpy change of combustion.[2]
8. (c)(ii)Write the equation for the complete combustion of sucrose.[1]
9. (c)(iii)The enthalpy change of reaction Z, ΔH, can be calculated using the enthalpy change of combustion data given in the table. substance | enthalpy change of combustion, ΔHc / kJmol⁻¹ ---|--- sucrose | −5643 glucose | −2805 fructose | −2810 Use the data in the table to calculate the enthalpy change for the reaction occurring when sucrose reacts with water, ΔH. You should draw a labelled Hess' cycle to show your working. ΔH = .............................................. kJ mol⁻¹[2]

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