# No of C=C bond in carbonyl compound

1. Aug 30, 2014

### somecelxis

1. The problem statement, all variables and given/known data

Compound X has the following composition by mass : carbon(64.3%) , 7.1% of hydrogen and oxygen (28.6%) . X reduces Fehling's solution to CuO . Copper( I) oxide .0.1 mol of X react with 4480cm3 of hydrogen gas in the presence of nickel catalyst. What 's the possible structural formula of X ?
there are 2 choices ..
CH2=CH-CHO
CH3-CH=CH-CH=CH-COH

THE ANS IS CH2=CH-CHO ...Why ? can anyone explain on this? thanks in advance!

2. Relevant equations

3. The attempt at a solution
mol of hydrogen gas = 4480/22400= 0.2 mol

if there's only one C=C bond , then 1 mol of X react with 1 mol of H2 gas ..

But 0.1 mol of X react with 0.2 mol H2 gas , so there are 2 C=C bond in X .... my choice would be CH3-CH=CH-CH=CH-COH ...
but the correct ans is CH2=CH-CHO

2. Aug 30, 2014

### Staff: Mentor

No idea about everything else, but of the two compounds given only one fits.

3. Aug 31, 2014

### somecelxis

so which one is correct?

4. Aug 31, 2014

### Staff: Mentor

Have you tried to find the experimental formula from the numbers given? Or even simpler - have you tried to find the percent elemental compositions from the given formulae?

5. Aug 31, 2014

### somecelxis

i got ratio of ratio of C:O = 3:4:1
using precentage