Question

9. A compound with a fragrant odor reacts with a dilute acid to give two compounds, A and B. Compound A is identified as an alcohol with the molecular weight of 32.0. Compound B is identified as an acid consisting of 48.7%C, 8.1 H% and 43.2% O. What is the name of the original compound? Show the work.

Answer 1

The compound A consists of -OH group, this corresponds to 17 g of the total molecular weight.

Rest of the molecular weight is 32-17 or 15 g. The only possibility of the composition of the chain is -CH₃.

So compound A is CH₃OH.

Compound B is an acid, it has a -COOH group. Mass of the O atoms in B is = 32 g

32 g is 43.2% of the molecular weight of B.

So the molecular weight of B is = 32*100/43.2 = 74 g

Molar mass of the side chain is= 74 - mass of COOH group = 74 - (32+12+1) = 29 g

the composition of the chain is -CH₂CH₃.

Compound B is CH₃CH₂COOH.

Original compound = ester of CH₃CH₂COOH and CH₃OH = CH₃CH₂COOCH₃