Chemistry 2002 JAMB Past Questions - Question 13: When dissolved in water, NaOH flakes show

Correct Answer

B

Explanation

When sodium hydroxide (NaOH) flakes are dissolved in water, they undergo a chemical reaction with water molecules to produce hydroxide ions (OH-) and sodium ions (Na+). The reaction can be represented as follows:

\[ \text{NaOH (s) + H}_2\text{O (l)} \rightarrow \text{Na}^+ (\text{aq}) + \text{OH}^- (\text{aq}) \]

In this reaction, solid sodium hydroxide (\(\text{NaOH}\)) reacts with liquid water (\(\text{H}_2\text{O}\)) to form aqueous sodium ions (\(\text{Na}^+\)) and hydroxide ions (\(\text{OH}^-\)). The resulting solution is alkaline because of the presence of hydroxide ions, which can increase the pH of the solution.

It's important to handle sodium hydroxide with care, as it is a strong base and can cause skin and eye irritation. When dissolving NaOH flakes in water, it's advisable to add the flakes to the water slowly while stirring, as the process is exothermic and can generate heat. Additionally, safety precautions such as wearing protective equipment should be taken to avoid contact with the substance.