Question

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 1

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 2

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,

`pH=-\log [H_3O^+]`

The hydronium ion concentration at pH = 5.

`5=-\log [H_3O^+]`

`[H_3O^+]=1* 10^(-5)M` ..............(1)

The hydronium ion concentration at pH = 3.

`3=-\log [H_3O^+]`

`[H_3O^+]=1* 10^(-3)M` ................(2)

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

`([H_3O^+]_(original))/([H_3O^+]_(final))=(1* 10^(-5))/(1* 10^(-3))=(1)/(100)`

`100* [H_3O^+]_(original)=[H_3O^+]_(final)`

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.