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Activity 3.5 — Burning Mg: Basic Oxide
NCERT Activity 3.5: Burn magnesium in air, dissolve the white ash (MgO) in water, and test with litmus paper. The red litmus turns blue — proving metal oxides are BASIC in nature.
How To Perform
1
Clean the Ribbon
Use sandpaper to remove the dull oxide coating until the ribbon is shiny silver.
2
Burn over Burner
Ignite the ribbon with a bunsen burner. A dazzling white flame produces white ash (MgO).
3
Dissolve Ash in Water
Collect the MgO ash on a watch glass, then add it to a beaker of water. MgO + H₂O → Mg(OH)₂.
4
Litmus Test
Dip red and blue litmus paper into the solution. Red litmus turns BLUE — the oxide is BASIC.
⚠️ Safety Notes
- •Do NOT stare at the burning magnesium — the UV-rich white light can damage your retina.
- •Use tongs to hold the ribbon — it burns at ~3100°C.
- •Collect ash on a watch glass, not bare hands.