9701 MCQ Solution 42 :

Question 42 : [Physical > Atoms, Molecules & Stoichiometry]

In the preparation of soft margarine, glyceryl trieleostearate

A  4

B  5

C  6

D  9

Reference: Past Exam Paper -June 2003 Paper 1 Q2

Solution 42:

Answer: B.

Glyceryl trieleostearate contains 3 chains . in the question its mentioned that the compound is hydrogenated therefore we are expecting hydrogen molecules to be added to the compound. in each of the compound’s chain there are 3 double bonds. and the question already told us that one of the side chains was converted to a new side chain which has now 2 double bonds instead of 3 this means that one hydrogen molecules was added to one side chain by electrophilic addition. the other 2 side chains are said to be converted to new side chains , in each of the 2 other side chains it said now it contains 1 double bond instead of 3 , this means in each side chain of the 2 remaining chains have 2 hydrogen molecules added to it. therefore one hydrogen molecules was added to one side chain. 2 hydrogen molecules were added to each of the two remaining side chains , this therefore make a total of 5 hydrogen molecules. therefore 5 moles of hydrogen since each hydrogen molecule contains 2 hydrogen atoms.