Answer to Question #153164 in General Chemistry for Fares

Question

How does dissolved CO2 affect the end point in the titration of Na2CO3 with HCl? Explain by using chemical formulas. Does the pH decrease or increase in the presence of dissolved CO2. anyone know hot answer this questions

Answer 1

The equation for the formula will be

HCl + Na2CO3 ----------- NaCl+H2O+CO2

Since we have a a strong acid reacting with a weak base ,then the solution produced at the end of the titration will also be slightly acidic.

Since we know CO2 is an acid anhydride which means when dissolved in water ,produces acid. So adding dissolved CO2 to the solution will continue to make the solution more acidic thereby reducing its PH.

For example if the solution had a PH of 5.5 before, when the dissolved CO2 is added to it the PH keeps going down from 5.4, 5.3, 5.2 downwards like that.