Question

Which one of the following statements best describes a solution with a pH of 3?

A) It has an H3O+ ion concentration of 1 × 10−3 mol/L and is basic.
B) It has an H3O+ ion concentration of 1 × 103 mol/L and is acidic.
C) It has an H3O+ ion concentration of 1 × 103 mol/L and is basic.
D) It has an H3O+ ion concentration of 1 × 10−3 mol/L and is acidic.

Answer 1

Statement D is the correct option as the solution will have pH of 3. It has an H3O+ ion concentration of 1 ×
`10^(-3)` mol/L and is acidic.

Step-by-step explanation:

It is given in question that solution must have pH of 3. The value if being less than 7 shows that solution is acidic. The pH value of 3 indicates that given solution is highly acidic and has strong acid. Strong acid gets fully dissociated into
`H_(3)`
`O^(+)` ions.

pH of the solution is calculated as:

pH = -log10[
`H_(3)`
`O^(+)`]

the concentration or molarity of the hydronium ion is given as moles/litre

concentration of hydronium ion in the solution is 1 X
`10^(-3)` moles/litre

putting the values in the equation:

pH = - log10( 1 X
`10^(-3)`)

pH = 3 (acidic)

Thus it can be concluded that D option is the right answer.