why is there a need to use boiled distilled water in our titration experiment?
Saturday, January 2nd, 2010 at
7:38 pm
IS there something that makes it more pure than the distilled water? How? Thanks!
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The reason that distilled water is boiled prior to use in preparing titration solutions is to remove dissolved CO2 which is present in all water. CO2 gas dissolved in water forms small amounts of H2CO3, or carbonic acid. Carbonic acid will alter the pH of the water, making it slightly acidic. Given that this small amount of carbonic acid can distort the results of an acid/base titration, it is common to boil the water to release as much of the CO2, thereby getting the water to around pH 7. This can be easily observed if a pH meter is placed into unboiled distilled water, the pH will be around 5-6, depending on the quality of water being used.
Distilled water IS produced from boiling water. The goal is to avoid trace elements in tap-water that could introduce inaccuracy into titrations, particularly with compounds that cause alkalinity.