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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: cloudy1290 on June 21, 2019, 11:58:48 PM

Title: Equation with unknown compound is given, find that and product after hydrolysed
Post by: cloudy1290 on June 21, 2019, 11:58:48 PM: This question was from the test today, so I remembered as much as I could

A + O2 ---> CO2 + H2O
Given that A is CxHyOz, mass of CO2 is 110mg, mass of H2O is 40.5mg and mass of A is 50.5mg
and they said about result after products(B C D and E, I can't remember which one they mentioned) react with Tollen and Fehling. And 1 of them was added by Na to give H2
1. Find x,y,z and find A
2. Hydrolyze A and the products will be B+C (B has 2 moles, and C has 1 mol). Find B and C
3. Then C oxidize to D, D oxidize to E. Find D and E

my solution :
CxHyOz + (x + y/4 - z/2)O2 ----> xCO2 + (y/2)H2O
50.5/12x+y+16z = 110/44x = 40.5/9y
= 101/12x+y+16z = 5/x = 9/y

and from equation I solved and got x = 5y/9, y= 9z/2 then substituted y into x
so x : y : z = 5z/2 : 9z/2 : z = 5 : 9 : 1 so A is C5H9O2

I have searched and got 3 compounds : Cyclopentanolate, 4-Hydroxy-2-methylenebutyl and Hydroxypentyl. But I couldn't found the products after hydrolyzed
Title: Re: Equation with unknown compound is given, find that and product after hydrolysed
Post by: AWK on June 22, 2019, 01:54:23 AM: First of all, an organic compound containing only CHO should contain even number of hydrogen atoms.
Title: Re: Equation with unknown compound is given, find that and product after hydrolysed
Post by: cloudy1290 on June 22, 2019, 02:00:18 AM: Quote from: AWK on June 22, 2019, 01:54:23 AM
First of all, an organic compound containing only CHO should contain even number of hydrogen atoms.

The masses I wrote were all correct. And I don't really have any idea.
Title: Re: Equation with unknown compound is given, find that and product after hydrolysed
Post by: AWK on June 22, 2019, 02:18:05 AM: Double your empirical formula and check oxygen
Title: Re: Equation with unknown compound is given, find that and product after hydrolysed
Post by: cloudy1290 on June 22, 2019, 02:33:14 AM: Quote from: AWK on June 22, 2019, 02:18:05 AM
Double your empirical formula and check oxygen

it becomes C10H18O2, and its name is citronellic acid. But what do you mean "check oxygen"?

sorry i'm not fluent with english
Title: Re: Equation with unknown compound is given, find that and product after hydrolysed
Post by: cloudy1290 on June 22, 2019, 02:34:16 AM: what do you mean "check oxygen"
Title: Re: Equation with unknown compound is given, find that and product after hydrolysed
Post by: cloudy1290 on June 22, 2019, 02:34:38 AM: Quote from: AWK on June 22, 2019, 02:18:05 AM
Double your empirical formula and check oxygen

Oh actually it was C5H9O2
Title: Re: Equation with unknown compound is given, find that and product after hydrolysed
Post by: AWK on June 22, 2019, 02:35:52 AM: and doubled empirical formula?
Title: Re: Equation with unknown compound is given, find that and product after hydrolysed
Post by: cloudy1290 on June 22, 2019, 02:44:02 AM: Quote from: AWK on June 22, 2019, 02:35:52 AM
and doubled empirical formula?

then it will be C10H8O4, I'm still finding what it is
Title: Re: Equation with unknown compound is given, find that and product after hydrolysed
Post by: AWK on June 22, 2019, 02:50:39 AM: H8 or H18?
Title: Re: Equation with unknown compound is given, find that and product after hydrolysed
Post by: cloudy1290 on June 22, 2019, 02:58:28 AM: Quote from: AWK on June 22, 2019, 02:50:39 AM
H8 or H18?

sorry mistyped, it's 18. Maybe Sebacic acid ?
Title: Re: Equation with unknown compound is given, find that and product after hydrolysed
Post by: AWK on June 22, 2019, 03:05:12 AM: Could you hydrolyze this compound?
Title: Re: Equation with unknown compound is given, find that and product after hydrolysed
Post by: cloudy1290 on June 22, 2019, 03:09:36 AM: Quote from: AWK on June 22, 2019, 03:05:12 AM
Could you hydrolyze this compound?

I'm not good with Org Chem. But I think the question was wrong or my calculation method was wrong
Title: Re: Equation with unknown compound is given, find that and product after hydrolysed
Post by: AWK on June 22, 2019, 03:16:03 AM: It is rather impossible to determine a unique compound from your data. But from 2:1 ratio of hydrolysis products you can recognize for example ester of dicarboxylic acid.