Aspirin prac. How to test if H2SO4 acted as a catalyst?

[AllAboutTheLGs]

How do you test if sulphuric acid did not react with the reagents and only acted as a catalyst?
I've heard about adding Barium Chloride and precipitating it but can someone explain it more for me?

[Hellrocks]

The definition of a true catalyst is one that does not get consumed in the reaction while it speeds up the rate of the chemical reaction
Note that BaSO4 is insoluble, if we can determine that the amount of H2SO4 added is the same as the amount precipitated, we can confirm that H2SO4 is not consumed in the reaction.

[AllAboutTheLGs]

But when you precipitate the H2SO4, won't there be errors when calculating the amount of it? For example say there was a loss of precipitate during transfer/filtration of the barium sulphate, wouldnt that result in a lower calculated amount for H2SO4, hence inaccurate determination on whether the catalyst was consumed?

[Hellrocks]

These errors exist in any experiments. You look at the products and how much was consumed, you can reasonably estimate whether H2SO4 was a reactant or catalyst.

[doh07]

H2SO4 only speeds up a reaction, hence it's not necessary for the reaction to occur. Try not using H2SO4 and if aspirin is produced anyways, then we can safely say it's not a reactant. Rather, it's a catalyst

[LukeHigham]

One option would be to monitor the pH throughout the course of the reaction. If the acid is a catalyst then the pH should change significantly.
Alternatively, perform a titration at the end of the reaction to confirm the acid concentration has not changed.

Also, repeat reaction without acid to see if the rate is slower.

If the rate is slower without acid and no acid has been consumed (titration confirms this) then H2SO4 is probably a catalyst.

[AllAboutTheLGs]

I just had my SAC. got most of it right except the rattest question on activation energies. I just guessed hopefully it isn't wrong

[charmanderp]

Catalyst causes a decrease in activation energy (not directly but it has this effect).

For some reason I wrote that aspirin is aka as acetylsalicylate. That's correct but acetylsalicylic acid would have been a better option. I messed up the methylsalicylate question for sure ):

[AllAboutTheLGs]

I realised after the sac that it decreased.... -sigh. First time in my life that I 've seen that term