# Why does a reaction stop when turning into a solid?

I recently was looking at a question about the volume of carbon dioxide produced when reacting calcium carbonate with dilute sulfuric acid and using nitric acid. In the answer it says that calcium sulfate is produced which is a solid which stops the reaction, but I don't get why … calcium nitrate produces and aqueous solution which causes the reaction to carry on reacting. The reaction equation is:

$$\ce{CaCO3(s) + H2SO4(aq) -> CaSO4(s) + H2O(l) + CO2(g)}$$

$$\ce{CaCO3(s) + 2HNO3(aq) -> Ca(NO3)2(aq) + H2O(l) + CO2(g)}$$

• Wait, you’re using a solid block of $\ce{CaCO3}$ and throwing that into the diluted acid mixtures? *Had to think about that for a while* – Jan Nov 4 '15 at 22:56
• I think you mean "The nitric acid produces water which should cause the reaction to carry on reacting." – MaxW Nov 5 '15 at 0:35
• @MaxW why does the water cause it to keep reacting? – super123 Nov 5 '15 at 0:59
• I don't understand your inquiry. Your problem statement first says that the reaction stops, then it says that it keeps going. – MaxW Nov 5 '15 at 1:08