Chemistry 9701 · AS & A Level · An introduction to AS Level organic chemistry

An introduction to AS Level organic chemistry — practice question

In reaction A, sucrose, $\text{C}_{12}\text{H}_{22}\text{O}_{11}$, combines with water to give glucose and fructose: $\text{C}_{12}\text{H}_{22}\text{O}_{11} + \text{H}_2\text{O} \rightarrow$ glucose $+$ fructose.
(a)[1]

Suggest a name for this kind of reaction.

(b)[2]

Explain in detail why glucose and fructose are a pair of structural isomers. Your response must refer specifically to these two molecules.

(c(i))[1]

The activation energy for reaction B is $+29\,\text{kJ mol}^{-1}$. Predict the activation energy of reaction A.

(c(ii))[1]

The enthalpy change for reaction A is $-14\,\text{kJ mol}^{-1}$. Predict the enthalpy change for reaction B.

(c(iii))[2]

Sketch a labelled energy level diagram for reaction B. Include the relevant values from (c)(i) and (c)(ii).

(d(i))[2]

Explain the meaning of the term enthalpy change of combustion of sucrose.

(d(ii))[3]

Use the Data Booklet to calculate the enthalpy change, in $\text{kJ mol}^{-1}$, for the combustion of sucrose. Assume that every bit of heat energy produced is transferred to the water. Show your working.

(d)

A sample of 1.00 g of sucrose, $\text{C}_{12}\text{H}_{22}\text{O}_{11}$, is completely combusted. The heat energy released is used to raise the temperature of 250 g of water in a calorimeter from $25.0\,^{\circ}\text{C}$ to $40.7\,^{\circ}\text{C}$. These data can then be used to calculate the enthalpy change of combustion of sucrose.

Worked solution & mark scheme

This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: Hydrolysis

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI