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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Problem of the Week Archive => Topic started by: Borek on April 02, 2012, 06:28:13 AM

Title: Problem of the week - 02/04/2012
Post by: Borek on April 02, 2012, 06:28:13 AM

Nice smelling organic compound A was hydrolyzed in acidic conditions, yielding compounds B and C. Compound B was identified as an alcohol with a vapor density identical to the density of a pure oxygen. Compound C was a carboxylic acid. Reducing compound C with LAH yields another compound D with molar mass of 60 g/mol and composition: 60%C, 13.4%H, 26.6%O.

Give names and formulas of all compounds A, B, C and D.

Title: Re: Problem of the week - 02/04/2012
Post by: XGen on April 02, 2012, 08:56:53 AM

Vapor density is the density of vapor in relation to hydrogen gas, and can be expressed in the equation:

vapor density = molar mass of gas/molar mass of H₂.

Using this, we can find the vapor density of pure oxygen to be 16, and the molar mass of compound B to be 32 g/mol.

Because Compound B is an alcohol, it must be the only alcohol with molar mass 32, which is methanol (CH₃OH).

Compound D has a composition 60% C, 13.4% H, and 26.6 % O. Assuming 100g and dividing each of these by their molar masses, the formula appears to be C₅H_13.3O_1.66. Simplifying this, the formula becomes C₃H₈O. Compound D is therefore n-propanol, because Compound C is a carboxylic acid.

This means that Compound C is propanoic acid.

With propanoic acid and methanol, the ester is methyl propanoate.

My final answers are:
Compound A: methyl propanoate, (CH₃CH₂COOCH₃)
Compound B: methanol, (CH₃OH)
Compound C: propanoic acid, (CH₃CH₂COOH)
Compound D: propanol, (CH₃CH₂COOH)

Title: Re: Problem of the week - 02/04/2012
Post by: Borek on April 02, 2012, 09:41:13 AM

I had a feeling it can be too easy, but I wanted something at least partially organic  :-\