Question

When sodium hydroxide reacts with sand, it forms :

• A. sodium silicate
• B. silicon oxide
• C. silicon hydroxide
• D. none of the above

Hint:

Silica reacts with strong bases to form silicates.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Sand consists mainly of silica (\( \text{SiO}_{2} \)). It is an acidic oxide and reacts with strong bases like sodium hydroxide.
Step 2: Detailed Explanation:
When silica (\( \text{SiO}_{2} \)) is heated with concentrated aqueous sodium hydroxide (\( \text{NaOH} \)) or fused with it, it dissolves to form a salt called sodium silicate.
The chemical reaction is:
\[ \text{SiO}_{2}(\text{s}) + 2\text{NaOH}(\text{aq}) \longrightarrow \text{Na}_{2}\text{SiO}_{3}(\text{aq}) + \text{H}_{2}\text{O}(\text{l}) \]
Sodium silicate (\( \text{Na}_{2}\text{SiO}_{3} \)) is also known as "water glass" because it is a silicate salt that is soluble in water.
Step 3: Final Answer:
The reaction of sand with sodium hydroxide produces sodium silicate.