Method of work

In a beaker, take 60 mL of water from the source (under a stream), pour it into an Erlenmeyer flask, add a couple of K-Na-tartrate crystals and 5 drops of phenolphthalein, and then titrate with a standard Na2CO3 solution (24.09 g/L) until a purple color appears. color that must be stable for 3 minutes. The CO2 content (expressed in mg/L) is calculated by multiplying the number of mL of Na2CO3 consumed in the titration by a factor of 250.