Question

The inversion of cane sugar to produce glucose and fructose is represented by the reaction
\[{{C}_{12}}{{H}_{22}}{{O}_{11}}+{{H}_{2}}O\xrightarrow{{{H}^{+}}}{{C}_{6}}{{H}_{12}}{{O}_{6}}+{{C}_{6}}{{H}_{12}}{{O}_{6}}\]
This reaction is :
(A) second order
(B) unimolecular
(C) pseudo unimolecular
(D) bi-molecular

Answer 1

Hint: Sucrose split into its monosaccharide component on heating with aqueous solution, or by action of enzyme sucrose or by treatment with dilute acid. Molecularity and order of the reaction are most of the time the same for a reaction.

Complete step by step answer:
The molecularity of a reaction is defined as the number of reacting molecules which collide simultaneously to bring about a chemical reaction. In other words, the molecularity of an elementary is defined as the number of reactant molecules taking part in the reaction.
The order of reaction refers to the relationship between the rate of a chemical reaction and the concentration of the species taking part in it. The order of reaction can be defined as the power dependence of rate on the concentration of all reactants.
Sucrose , commonly known as, Table sugar or cane sugar, is a carbohydrate formed from the combination of glucose and fructose. Glucose is the simple carbohydrate formed as a result of photosynthesis. Fructose is nearly identical, except for the location of a double-bonded oxygen. They are both six-carbon molecules, but fructose has a slightly different configuration. When the two combine, they become sucrose.
The inversion reaction of sucrose is :
\[{{C}_{12}}{{H}_{22}}{{O}_{11}}+{{H}_{2}}O\xrightarrow{{{H}^{+}}}{{C}_{6}}{{H}_{12}}{{O}_{6}}+{{C}_{6}}{{H}_{12}}{{O}_{6}}\]
The reaction involves water and sucrose, since it involves two reacting species, the molecularity of the reaction will be two but since, water is present in excess, therefore, the order of the reaction will be first order, and reaction will be pseudo unimolecular reaction.
Therefore, the correct answer is the C option.

Note: Most carbohydrates are optically active, that is they rotate the plane of polarization of the plane polarized light. Sucrose is dextrorotatory, that is it rotates the plane to right, while the mixture of glucose and fructose is laevorotatory, that is it rotates the plane to the left. So, as sucrose is hydrolysed,the extent of rotation progressively decreases until the direction of rotation changes from right to left. This process is called inversion.