question_answer

The hydrogen ion concentration of a \[{{10}^{-8}}M\text{ }HCl\] aqueous solution at \[298\text{ }K\text{ (}{{K}_{w}}={{10}^{-14}})\] is:                                                                                 [AIPMT (S) 2006]

A)  \[1.0\times {{10}^{-6}}M\]

B)                   \[1.0525\times {{10}^{-7}}M\]

C)  \[9.525\times {{10}^{-8}}M\]

D)       \[1.0\times {{10}^{-8}}M\]

Correct Answer: B

Solution :

In aqueous solution of 10-8 M HCl, [H+] is based upon the concentration of H+ ion of 10-8 M HCl and concentration of H+ ion of water

Kw of H2O = 10-14 = [H+] [OH-]

or [H+] = 10-7 M (due to its neutral behaviour)

So, in aqueous solution of ,

[H+] = [H+] of HCl + [H+] of water

Hence, answer is nearer to [b].