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Activity 2.7 — Non-metal Oxide + Base
NCERT Activity 2.7: Pass CO₂ through NaOH solution (with phenolphthalein). The pink colour disappears as CO₂ (an acidic oxide) neutralises the base. Mirror of Activity 2.6.
How To Perform
1
Add NaOH + Phenolphthalein
NaOH + a few drops of phenolphthalein → solution turns PINK (basic).
2
Pass CO₂ Gas
Bubble CO₂ through the pink solution.
3
Observe
Pink colour fades → colourless. NaOH neutralised.
4
Conclude
2NaOH + CO₂ → Na₂CO₃ + H₂O. Acidic oxide + base = neutralisation.
⚠️ Safety Notes
- •NaOH is caustic — wear goggles.
- •CO₂ is not toxic but can displace oxygen in a closed room — ventilate.
- •Handle phenolphthalein carefully — it stains.