Calculating the pH of a solution made up of 2 acids of different volumes and concentrations

By the end of this video, you should be able to calcule the pH of a solution made up of 2 acids of different volumes and concentrations.

Calculate the pH of the resulting solution when 300 cm3 of a solution containing a hydrogen ion concentration of 0.200 mol dm-3 is completely mixed with 150 cm3 of a solution containing a hydrogen ion concentration of 0.100 mol dm-3

ANS
ANS
1. Calculate the number of moles of hydrogen ions for each solution through n=cv
n1= C1V1= (0.2)(300 x 10-3) = 0.06 mol n2= C2V2= (0.1)(150 x 10-3) = 0.015 mol

2. Add the number of moles for each solution together.
n = n1 + n2 = 0.06 + 0.015 = 0.075 mol of H+ in 450 cm3

3. Calculate the concentration of hydrogen ions [H+]= 𝐧/𝐕 where v is the total volume of the 2 solutions.

4. pH= -log[H+]
pH = -log[0.167] = 0.78