I'm not sure if this is the right spot for this, but I didn't want to bug people in the undergraduate forums with a question about basic bench methods (again).
I want to experimentally measure pH of a standard limewater (Ca(OH)2) solution. Simple enough, but I'm stuck with a few limitations.
Firstly, I only have tap water, and the tap water is loaded with dissolved CO2. The carbon dioxide-carbonate equilibrium will throw off the pH to begin with, but more importantly it will react with the calcium and precipitate calcium carbonate. It would seem that I just answered my own question, but there's another limitation.
Secondly, I have only 1-2g of powdered Ca(OH)2. I don't know how much CO2 I will need to remove and even if I used the calcium hydroxide to remove the CO2, the pH would be thrown off by the lingering hydroxide ions. I won't know what the concentration of hydroxide ions left over will be because some of them will be neutralized by an unknown amount of hydronium released by the carbon dioxide-carbonate equilibrium shift. I don't know the concentration of CO2 in the tapwater.
I was thinking of heating the water, but I'm not sure how effective that'll be. Any help?