[maleicacid]

Hello, I'm new to this website, so hopefully I'm posting this question in the right forum.

Anyways, I'm trying to calculate the theoretical yields of maleic and fumaric acid synthesized from maleic anhydride.

In our lab, we synthesized maleic acid by adding maleic anhydride to hot distilled water and cooling it down for crystallization. The crystals of maleic acid were then filtered out from the solution by vaccum filtration. 

This first part seems straight forward as the involved reaction would be...
Maleic anhydride + H2O ==> Maleic acid
...and I can calculate the theoretical yield of maleic acid.

Now, it's the next part that seems a bit complicated to me. After filtering our maleic acid crystals, we then added HCl to the leftover filtrate solution, boiled it, and cooled it down to crystallize fumaric acid.

I believe the reaction for this part would be...
Maleic acid left over in the filtrate ==(HCl as a catalyst)==> Fumaric acid???

So, I guess some maleic acids that were not crystallized and still dissolved in the filtrate solution turned into fumaric acid? If so, how do I find the mass of the maleic acid remaining in the filtrate solution to calculate the yield of fumaric acid?

Sorry if this sounds confusing. Feel free to ask for any clarification if you need. I'll look forward to your replies

[AWK]

...and I can calculate the theoretical yield of maleic acid

Theoretical yield is always 100 %. You calculated the real yield of maleic acid! But for goodness sake show your calculations.

Nothing suspected.
Just weight, and calculate weight as previously, but now it will be the yield of fumaric acid. Note, the sum of yields should be less than 100 %.