What is the pH of 10-9 M HCl?
Here , [H+] for acid is < 10 -7 { which is not possible }
so,
total [H+] = 10 -7 + 10 -9
= 1.01 x 10 -7
Thus, pH = - log [H+]
= 6.99
What is the pH of a solution of NaOH whose concentration is 0.4g/liter?
NaOH ------> Na+ + OH-
given, [NaOH] = 0.4 g/liter
molecular mass of NaOH is 40 g/mol.
thus, Molarity of the solution = 0.4 / 40
=1/100 = 10 -2 mole/liter
now, from the dissociation pattern of NaOH
[NaOH] = [OH-] = 10 -2
thus, pOH = -log [OH-]
= 2
thus, pH = 14 - pOH
= 12