Question

What will be the pH of the resulting solution if to a 100 ml of HCl solution of pH = 1 , 900ml of disstilled water is added?

Answer 1

concentration of hydrogen ions in the solution = H⁺= 10 (⁻ph)

= 10 ⁻¹ = 0.1 M

M1V1 = M2V2
0.1 x 100 = M2 x (100+900)
M2= 0.01 M

the concentration of HCl after the addition of 900ml of water = 0.01 M

New pH= -log (0.01)= 2

Answer 2

Concentration of H positive ions in the solution  

[H+] = 10(raise to power –pH) 

= 10 raise to power negative 1  = 0.1 M 

M1V1 = M2V2 

0.1M x 100ml = M2 x (100+900) ml 

M2 = 0.01M  

The concentration of HCl after addition of 900 ml distilled water is 0.01M 

Now, pH = -log(0.01) = 2 

pH of resulting solution is 2