I have two substances potassium sulfate and potassium carbonate. They are unlabelled and I need to know which one is which. If I add HCl to each substance ie

K2SO4(s) + 2HCl(aq)-->2KCl(aq) + H2SO4(aq)

K2CO3(s) + 2HCl(aq)--> 2KCl(aq) + H2O(l) + CO2(g)

What would I observe in each reaction?

Note that one of the prodcuts of one reaction is a gas. That should be a clue as to what the answer is.

I think I would observe bubbling/fizzing in the second equation, is that correct?

Agreed

Yes, you are correct. When you add HCl to potassium carbonate (K2CO3), you will observe bubbling or fizzing in the reaction. The bubbling is due to the formation of carbon dioxide gas (CO2) as one of the products of the reaction.

On the other hand, when you add HCl to potassium sulfate (K2SO4), there will be no bubbling or fizzing. Instead, you will observe the formation of a clear solution, as potassium chloride (KCl) and sulfuric acid (H2SO4) are formed as products.

Therefore, by observing the reaction with HCl, you can determine the identity of the substances. The one that shows bubbling or fizzing is potassium carbonate (K2CO3), and the one that does not is potassium sulfate (K2SO4).