Question

What is the hydrogen ion and hydroxide ion concentration for a pH of 4.478? Is the solution acid or base?

Answer 1

The hydrogen ion concentration, [H⁺] is 3.327 x 10⁻⁵ M

The hydroxide ion concentration [OH⁻] is 3.01 x 10⁻¹⁰ M

The solution is acid.

Step-by-step explanation

pH is a measure of how acidic or basic a solution is. The range goes from 0 - 14, with 7 being neutral. A pH of less than 7 indicates acidity, whereas a pH of greater than 7 indicates a base. pH is really a measure of the relative amount of free hydrogen and hydroxyl ions in the solution.

Since pH of the solution is 4.478, then it means the solution is acid.

The hydrogen ion concentration, [H⁺] of the solution can be calculated using the pH formula.

`pH=-log[H^+]`

Substituting pH as 4.478 into the formula, we have

`\begin{gathered} 4.478=-log[H^+] \\ \\ Multiply\text{ }through\text{ }by\text{ }minus\text{ }(-) \\ \\ log[H^+]=-4.478 \\ \\ .[H^+]=10^(-4.478) \\ \\ .[H^+]=3.327*10^(-5)\text{ }M \end{gathered}`

The hydrogen ion concentration, [H⁺] is 3.327 x 10⁻⁵ M

The relation between the hydrogen ion concentration, [H⁺] and hydroxide ion concentration [OH⁻] is

`.[H^+]*[OH^-]=10^(-14)`

So, substituting [H⁺] as 3.327 x 10⁻⁵ M, we have:

`\begin{gathered} 3.327*10^(-5)*[OH^-]=10^(-14) \\ \\ Divide\text{ }both\text{ }sides\text{ }by\text{ }3.327*10^(-5) \\ \\ (3.327*10^(-5)**[OH^-])/(3.327*10^(-5))=(10^(-14))/(3.327*10^(-5)) \\ \\ .[OH^-]=3.01*10^(-10)\text{ }M \end{gathered}`

Hence, the hydroxide ion concentration [OH⁻] is 3.01 x 10⁻¹⁰ M