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Chemistry Practical Query

I am currently doing a salt prep practical in chemistry. We were given the exam booklet so I had time to quickly have a look at the evaluation questions.

One of the evaluation questions was: Suggest a reason why the procedure in step 2 and 3 is only possible with a carbonate that is insoluble in water, such as magnesium carbonate.

To give some background info, we are producing the salt Magnesium Sulfate by dissolving Magnesium Carbonate in Sulfuric Acid. During step 2 we were dissolving the Magnesium Carbonate in Sulfuric Acid until we had a slight excess. In step 3 we then heated the Sulfuric Acid with an excess of Magnesium Carbonate to see if it was truly in excess.

I am really not sure as to the answer of that question. Could someone help?
So you are doing edexcel?
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GCSEBen
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Original post by GrandMasti
So you are doing edexcel?


Yes, sorry forgot to mention that
Original post by GCSEBen
Yes, sorry forgot to mention that


Ah right. I think the answer is since only with an insoluble one you could tell when the reaction was over :wink:

Have you done any other of the edexcel assessed practicals?
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Original post by GrandMasti
Ah right. I think the answer is since only with an insoluble one you could tell when the reaction was over :wink:

Have you done any other of the edexcel assessed practicals?


Thanks for answering. Would you be able to elaborate a bit as I am slightly unsure as to what you mean :smile:

Yes, I have done the acid-base titration and energetics assessed practicals.
Original post by GCSEBen
Thanks for answering. Would you be able to elaborate a bit as I am slightly unsure as to what you mean :smile:

Yes, I have done the acid-base titration and energetics assessed practicals.


So with an insoluble salt, when you add it in excess, you can visibly see an excess at the bottom after the reaction has finished. With a soluble one it would just dissolve and not indicate when all of the acid has reacted, I think?

Could I ask you if you have done the qualitative observation practical?
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GCSEBen
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Original post by GrandMasti
So with an insoluble salt, when you add it in excess, you can visibly see an excess at the bottom after the reaction has finished. With a soluble one it would just dissolve and not indicate when all of the acid has reacted, I think?

Could I ask you if you have done the qualitative observation practical?


But surely that wouldn't matter as we are dissolving it in sulfuric acid not in water. What does it being insoluble in water have to do with dissolving the carbonate in sulfuric acid?

I am doing the qualitative observation practical in two weeks
Original post by GCSEBen
But surely that wouldn't matter as we are dissolving it in sulfuric acid not in water. What does it being insoluble in water have to do with dissolving the carbonate in sulfuric acid?

I am doing the qualitative observation practical in two weeks


But remember the sulfuric acid is a solution (it contains water)

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