Summary Topper’s Ultimate Reaction Revision Sheet

Important Chemical Reactions with Observations
(ICSE Class 9)
Reaction: Fe + CuSO■ → FeSO■ + Cu
Type: Displacement reaction
Observation: Blue CuSO■ solution turns pale green; reddish-brown copper is deposited.

Reaction: 2Pb(NO■)■ (heat) → 2PbO + 4NO■ + O■
Type: Thermal decomposition
Observation: White Pb(NO■)■ forms yellow PbO; brown fumes of NO■ gas are released.

Reaction: CuCO■ (heat) → CuO + CO■
Type: Thermal decomposition
Observation: Green CuCO■ turns black (CuO); CO■ gas turns limewater milky.

Reaction: AgNO■ + NaCl → AgCl↓ + NaNO■
Type: Precipitation (Double Displacement)
Observation: White curdy precipitate of AgCl forms; it darkens on exposure to light.

Reaction: Zn + H■SO■ → ZnSO■ + H■↑
Type: Displacement reaction
Observation: Effervescence observed; colourless hydrogen gas released with pop sound.

Reaction: CuSO■ + 2NH■OH → Cu(OH)■↓ + (NH■)■SO■
Type: Double displacement
Observation: Light blue precipitate of Cu(OH)■; dissolves in excess NH■OH to give deep blue
solution.

Reaction: K■Cr■O■ + 3SO■ + H■SO■ → Cr■(SO■)■ + K■SO■ + H■O
Type: Redox reaction
Observation: Orange K■Cr■O■ turns green due to formation of Cr³■ ions.

Reaction: Cu + 4HNO■ → Cu(NO■)■ + 2NO■ + 2H■O
Type: Redox reaction
Observation: Brown fumes of NO■ observed; blue Cu(NO■)■ solution forms.

Reaction: Ca(OH)■ + CO■ → CaCO■↓ + H■O
Type: Combination reaction
Observation: White precipitate of CaCO■ forms; limewater turns milky.

Reaction: 2NH■OH + HCl → NH■Cl + H■O
Type: Neutralization
Observation: No visible change; exothermic reaction producing heat.

Reaction: Pb(NO■)■ (heat) → PbO + NO■ + O■
Type: Thermal decomposition