Select all of the following that are strong bases: NaOH Ca(OH)2 AgOH Pb(OH)2 Mn(OH)2
The strong bases among the options listed are:
- NaOH (Sodium Hydroxide)
- Ca(OH)2 (Calcium Hydroxide)
Explanation:
Strong bases are substances that dissociate completely in water, releasing hydroxide ions (OH⁻) to form a highly basic solution. The ability of a base to dissociate completely into its ions determines whether it is classified as a strong base or a weak base.
- NaOH (Sodium Hydroxide): Sodium hydroxide is a strong base because it dissociates completely in water. The dissociation reaction is: NaOH→Na++OH−\text{NaOH} \rightarrow \text{Na}^+ + \text{OH}^-NaOH→Na++OH− Since it dissociates fully, it is considered a strong base.
- Ca(OH)2 (Calcium Hydroxide): Calcium hydroxide is also a strong base. It dissociates relatively well in water, although not as completely as sodium hydroxide. The dissociation reaction is: Ca(OH)2→Ca2++2OH−\text{Ca(OH)}_2 \rightarrow \text{Ca}^{2+} + 2\text{OH}^-Ca(OH)2→Ca2++2OH− Despite the partial solubility in water, enough hydroxide ions are released to make it a strong base.
Why the others are not strong bases:
- AgOH (Silver Hydroxide): Silver hydroxide is a weak base. It is poorly soluble in water, and its dissociation does not proceed to completion. It tends to form a precipitate rather than dissociate fully into ions.
- Pb(OH)2 (Lead(II) Hydroxide): Lead(II) hydroxide is also a weak base. Like AgOH, it is not very soluble in water and does not dissociate completely. It dissolves slightly in water and forms a solution with a very low concentration of hydroxide ions.
- Mn(OH)2 (Manganese(II) Hydroxide): Manganese(II) hydroxide is another example of a weak base. It is slightly soluble in water and does not dissociate fully to release hydroxide ions.
In summary, NaOH and Ca(OH)2 are strong bases because they dissociate completely in water, while AgOH, Pb(OH)2, and Mn(OH)2 are weak bases due to poor solubility and incomplete dissociation.
