Carbonic acid (H2CO3) is a diprotic weak acid with the following Ka values: Ka1 = 4.5*10-7, Ka2 = 4.7 * 10-11

carbonic-acid
diprotic-weak-acid

#1

Carbonic acid (H2CO3) is a diprotic weak acid with the following Ka values: Ka1 = 4.510-7, Ka2 = 4.7 * 10-11. Calculate the pH of a solution that is prepared by adding 4.310-2 moles of NaHCO3 and 9.6 * 10-3 moles of Na2CO3 to a 1.00L volumetric flask and diluting it to the mark with water.

Answer:

When we mix NaHCO3 and Na2CO3 we get . calculate pH we use Henersson Hesselbah equation pH=pKa2 + logCO3 2-/HCO3-.Notice that CO3 2- is bronsted base and HCO3- is bronsted acid and we use Ka2.We first find concetrations because volume is 1 L C=n and pH will be =9.67