The resulting neutralised (which wasn't actually neutralised due to not realising CaCO3's insolubility) solution between Hydrochloric Acid and Calcium Carbonate, as per balanced equation CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O
turned red litmus paper blue, and universal indicator solution orange (repeated twice).
I performed another reaction between Citric Acid and Calcium Carbonate and I received consistently acidic results. There is a chance I might've mixed up these results though, and the Citric Acid reaction WAS the conflicting one.
I'm wondering if anyone could shed some light on why this might've happened? I'm guessing it can't be due to the insoluble calcium carbonate, as my other reaction didn't have issues.