30. pH of a solution of a strong acid is 5.0. What will be the pH of the solution obtained after diluting the given solution a 100 times?


Given, 
pH=5[H+]=10-5 mol L-1
On diluting the solution 100 times [H+]=10-5100=10-7 mol L-1
On calculating the pH using the equation pH=-log [H+], value of pH comes out to be 7. It is not possible. This indicates that solution is very dilute.
Hence, Total H+ ion concentration=H+ ions from acid+H+ ion from water
[H+]=10-7+10-7=2×10-7 MpH=-log [2×10-7]pH=7-0.3010=6.699