A strong base typically has a pH ranging from 12 to 14. This is because strong bases completely dissociate in water, resulting in a high concentration of hydroxide ions (OH⁻).
An example of a strong base is sodium hydroxide (NaOH). When dissolved in water, it dissociates completely:
\[ \text{NaOH} \rightarrow \text{Na}^+ + \text{OH}^- \]
If a 0.1 M solution of NaOH is prepared, the pH can be calculated as follows:
- The concentration of hydroxide ions (OH⁻) from the dissociation of NaOH is 0.1 M.
- Use the formula to find pOH: \[ \text{pOH} = -\log[\text{OH}^-] = -\log[0.1] = 1 \]
- Calculate pH using the relationship: \[ \text{pH} + \text{pOH} = 14 \] Thus, \[ \text{pH} = 14 - \text{pOH} = 14 - 1 = 13 \]
Therefore, the pH of a 0.1 M NaOH solution would be around 13, indicating it is a strong base.