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Limiting Reagent

Hi.

I Was doing a quick mole calculation for this reaction:

MgCO3 + H2SO4 ---> MgSO4 + CO2 + H2O

I found that there were 0.005 moles of sulphuric acid and 0.00356 moles of magnesium carbonate (using the information I was provided with).

I was wondering which number of moles I'd use to apply stoichiometry to the equation above, since as the sulphuric acid is in excess. Would I minus the lowest ratio of moles from the highest? I'm not entirely sure!

Thanks.
Original post by Sigma Bond
Hi.

I Was doing a quick mole calculation for this reaction:

MgCO3 + H2SO4 ---> MgSO4 + CO2 + H2O


What exactly are you trying to work out? If it is yield then just use the moles of magnesium carbonate. You don't need to take the difference or anything.
I would have thought that you just need the number of moles of MgCO3. The excess acid is just to ensure the reaction goes through to completion.

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Reply 3
Original post by ThisIsOurDecision
What exactly are you trying to work out? If it is yield then just use the moles of magnesium carbonate. You don't need to take the difference or anything.


I need to work out the volume of CO2 evolved (which according to the mark scheme is 71.4 cm3).
Reply 4
Magnesium carbonate is a limiting reagent, you can't produce more carbon dioxide by adding more sulfuric acid.

Strangely, to get the volume given I need to use rather low temps and increased pressure, as at STP 0.00356 moles of CO2 occupies 88.3 mL.
(edited 10 years ago)
Sulfuric acid is in excess so the limiting reagent is the magnesium carbonate.

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