When the pH of a solution changes from a pH of 5 to a pH of 3, the hydronium ion concentration is
A. 0.01 of the original content
B. 0.1 of the original content
C. 10 times the original content
D. 100 times the original content



Answer :

pH = -log( [H3O+] )
so the pH is in powers of 10
1* 10^ 5 / 1*10^3 = 1* 10^2 = 100
 so the answer is:
D. 100 times the original content

Answer : The correct option is, (D) 100 times the original content.

Explanation :

As we are given the pH of the solution change. Now we have to calculate the ratio of the hydronium ion concentration at pH = 5 and pH = 3

As we know that,

[tex]pH=-\log [H_3O^+][/tex]

The hydronium ion concentration at pH = 5.

[tex]5=-\log [H_3O^+][/tex]

[tex][H_3O^+]=1\times 10^{-5}M[/tex]      ..............(1)

The hydronium ion concentration at pH = 3.

[tex]3=-\log [H_3O^+][/tex]

[tex][H_3O^+]=1\times 10^{-3}M[/tex]      ................(2)

By dividing the equation 1 and 2 we get the ratio of the hydronium ion concentration.

[tex]\frac{[H_3O^+]_{original}}{[H_3O^+]_{final}}=\frac{1\times 10^{-5}}{1\times 10^{-3}}=\frac{1}{100}[/tex]

[tex]100\times [H_3O^+]_{original}=[H_3O^+]_{final}[/tex]

From this we conclude that when the pH of a solution changes from a pH of 5 to a pH of 3, the hydronium ion concentration is 100 times the original content.

Hence, the correct option is, (D) 100 times the original content.