Question

A fish tank containing a number of exotic fish needs a ph of 5.0 , an indicator indicates the ph of the tank is 7.0. what should be done to the hydrogen ion concentration to set the tank to the correct ph.

Answer 1

pH= (-log[H+ concentration])

The tank currently has a pH=7.0.

7.0= -log[H+]
10^-7= [H+]
[H+]= 0.0000001 moles of H+ per a Liter

The tank needs a pH of 5.0
10^-5.0= [H+]
[H+]= 0.00001 moles of H+ per a Liter

(0.00001)/(0.0000001)= 100

Answer: Therefore, the tank needs have an H+ concentration 100 times greater than its current concentration to reach a pH of 5.0.

Answer 2

A higher pH is less acidic than a lower pH.

pH = log { 1 / [H3O+] },where [H3O+] is the same that [H+].

Then, you need to decrease the pH of the solution from 7.0 to 5.0, which means you have to make it more acidic which is the same that increase the concentration of H+.

pH = 7.0 = log { 1/ [H3O+] } => [H3O+] = 10^-7M

pH = 5.0 = log { 1 / [H3O+] } => [H3O+]= 10^ - 5M

So, the answer is that to correct the pH, the concentration of hydrogen ionshall be increased from 10 ^ - 7 M to 10 ^ - 5M.