# Does the addition of acid change alkalinity? [closed]

I'm attempting to speed up the dissolution of calcium carbonate by the addition of hydrochloric acid. However, I'm using the calcium carbonate as a source of carbonate for a water sample. But would the addition of acid counteractively lower the alkalinity in the process, therefore lowering the carbonate concentration?

## closed as unclear what you're asking by Todd Minehardt, Buttonwood, paracetamol, jerepierre, ringoMay 31 '17 at 6:53

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• What do you mean exactly by "alkalinity" ? $\ce{HCl}$ dissolves carbonates by neutralizing them. If you need a known amount of carbonate in your solution, you cannot add any acid to it. You may want to use other methods to dissolve it, such as possibly complexation of calcium using EDTA. – Thomas Jungers May 29 '17 at 10:44
• Sorry, I mean the carbonate alkalinity. – thevancanfan May 29 '17 at 11:03
• Why aren't you using soda ash? It's alkaline and very soluble. Calcium carbonate is very poorly soluble in water. Check the wiki page link. – Phanz May 29 '17 at 12:23
• @Phanz I'm needing a source of calcium which contains carbonates. I already have a source of sodium through the addition of NaHCO3. I'm also considering using calcium hydroxide as my source of calcium and carbonates. – thevancanfan May 29 '17 at 12:30

Calcium carbonate has a solubility of $\pu{13 mg/L}$ at room temperature. Adding acid to this solution will dissolve the calcium carbonate, by destroying the carbonate via the equilibria $$\ce{CO3^2- <=>[+ H+][- H+] HCO3- <=>[+ H+][- H+] H2CO3 -> H2O + CO2,}$$ with the carbon dioxide having a tendency to escape the solution.