Asked by Jessica

A 94 mL vanillin solution with a concentration of 0.017 mol L-1 was made by extraction from 24.41 g of vanilla pods. Calculate the percentage of vanillin in the vanilla pods.

It would be helpful if you could explain to me the process to work out this question instead of just giving me the answer and not explaining how you got it.

Thanks in advance!
Answered by DrBob222
mols vanillin extracted = M x L = ?
g vanillin extrated = mols vanillin x molar mass vanillin.

Then % vanillin = (g extracted/g pods)*100 - ?
Answered by Jessica
Okay so this is my process:

Mass of Vanillin (C8H8O3) = molar mass x moles

152.15 x 0.017 = 2.59g

Mass of Vanillin = 2.59g
Mass of Vanilla pods = 24.41g

% of vanillin in vanilla pods:
(2.59 / 24.41g) x 100 = 10.61%

Does this sound right?
Answered by DrBob222
No,
You left out the first step. You never calculated mols.
mols vanillin extracted = M x L = ?
Answered by Jessica
I thought I already had moles though? Which was 0.017 Mol?
Answered by Jessica
I understand what you are talking about now because I did not factor in the 94mL. I have added this step in and now got 1.00%
Answered by DrBob222
The 0.017 mol L^-1 is 0.017 mols/L which is 0.017 M. You multiply that by 0.094 L to get mols.
Now I see your latest post. I obtained 0.996% which to two significant figures will round to 1.0%
Answered by Jessica
Yes I got 0.996% and rounded. Thanks very much for your help!
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