Question

Calculate the ph of hydronium ions in a 0.000 01 M solution of the strong acid HI.

A. 4
B. 2
C. 3
D. 5

Answer 1

D. 5

Step-by-step explanation:

`\mathbf{pH=-log_(10)[H^(+)]}`

The above formula is used to find pH of any solution. For that you require the concentration of
`\textrm{H}^(+)` or hydronium ion (
`\textrm{H}_(3)\textrm{O}^(+)`) in the solution. Concentration should be in molarity (M) to get the pH.

The concentration of
`\textrm{H}^(+)` ion is given as 0.00001 M or
`10^(-5)` M.

Substituting the value of
`\textrm{H}^(+)` ion in the formula:

`\textrm{pH}=- \textrm{log}_(10)[10^(-5)]`

`\textrm{pH}=-(-5)\textrm{log}_(10)[10]`

`\textrm{pH}=-(-5)(1)`

`\therefore\mathbf{pH=5}`

(NOTE : Some logarithmic properties

`\mathbf{log_(b)(b)=1}\\ \mathbf{log_(b)(a^(c))=c \cdot log_(b)(a)}`

here 'b' is called the base of log and '
`\mathbf{a^(c)}`' is called dthe argument of log. In the solution the base is '10' and the argument is
`\mathbf{H^(+)}`)