When the concentration of hydrogen ions in a solution is decreased by a factor of ten, the ph of the solution

a. increases by 1

b. increases by 10

c. decreases by 1

d. decreases by 10?

Knowing the concentration of the hydronium ion in moles per liter or molarity, the pH is calculated using the expression

pH = - log [H3O+]

If the concentration [H3O+] is decreased by a factor of 10, it becomes [H3O+]/10:

pH = - log [H3O+]/10

According to the quotient rule of the properties of logarithm, we can rewrite the above equation as

pH = - {log [H+] - log (10) ]

= - {log [H+] - 1}

= - log [H+] + 1

Therefore, the answer is a. increases by 1.