FINAL
FINAL REVISION
REVISION
, CHEMICAL REACTIONS & EQUATIONS
Balanced Chemical Equation: Pb(NO₃)₂ → PbO + NO₂ + O₂ MnO₂ + HCl → MnCl₂ + H₂O + Cl₂
1.Combination Reaction:
→
2Mg + O₂ 2MgO (white powder)
Mg ribbon should be cleaned with sandpaper before burning (removes MgO layer).
• It burns with a dazzling bright white flame.
• It is also an oxidation reaction (Mg gains oxygen).
• The reaction is exothermic (heat and light are produced).
CaO (s) + H₂O (l)→ Ca(OH)₂ (aq) + Heat EXOTHERMIC REACTIONS:
Slaked lime [Ca(OH)₂ solution] is used for whitewashing walls. 1. Burning of Natural Gas (Methane)
It reacts slowly with carbon dioxide (CO₂) from the air. CH₄ (g) + 2O₂ (g)→ CO₂ (g) + 2H₂O (g) + Heat
Calcium carbonate (CaCO₃) forms on the walls after 2–3 days. 2. Decomposition of Vegetable into Compost :
This thin layer of CaCO₃ gives walls a shiny finish. Vegetable waste → Compost (Khad) + Heat
Marble also has the same chemical formula: CaCO₃.
Ca(OH)₂ (aq) + CO₂ (g) → CaCO₃ (s) + H₂O (l) 3. Respiration is an Exothermic Process:
When Excess CO₂ is Passed: the white precipitate of CaCO₃
Reaction:C₆H₁₂O₆ (aq) + 6O₂ (aq) → 6CO₂ (aq) + 6H₂O (l) + Energy
ENDOTHERMIC REACTIONS:
dissolves. It forms soluble calcium hydrogen carbonate.
→
CaCO₃ (s)+CO₂ (g)+H₂O (l) Ca(HCO₃)₂ (aq)
Photosynthesis : 6CO₂ (g) + 6H₂O (l) → C₆H₁₂O₆ (aq) + 6O₂ (g)
(In presence of sunlight and chlorophyll)
, 2.Decomposition Reaction:
Thermal Decomposition Electrolytic decomposition: Photolytic Decomposition:
• Balanced equation: 2H₂O(l) → 2H₂(g) + O₂(g). 2AgCl(s)→ 2Ag(s) + Cl₂(g) (in sunlight)
• FeSO₄·7H₂O (green crystals) first lose water on • Hydrogen is released at the cathode (reduction). • Silver chloride (AgCl) is white in colour.
heating and turn white. • Oxygen is released at the anode (oxidation). • On exposure to sunlight, it turns grey due to
• On strong heating, white FeSO₄ decomposes to • Volume ratio of H₂ : O₂ = 2 : 1. formation of silver (Ag).
form brown Fe₂O₃. • Mass ratio of H₂ : O₂ = 1 : 8. • Chlorine gas (Cl₂) is released.
• Pungent smelling gases SO₂ and SO₃ are evolved • Dilute acid is added to increase conductivity (pure • Silver chloride is photosensitive; hence stored in
water is a poor conductor). dark-coloured bottles.
(cause acid rain).
• Reactions: FeSO₄·7H₂O→ FeSO₄ + 7H₂O • Similar reaction: 2AgBr(s) → 2Ag(s) + Br₂(g) (in
2FeSO₄ → Fe₂O₃ + SO₂ + SO₃ Oxygen Test: When a glowing splint is inserted
sunlight)
• Used in black-and-white photography.
into the gas, it relights, confirming oxygen is
present.
2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂ Carbon dioxide Test: Bubble the gas through
• On heating, lead nitrate decomposes. lime water (calcium hydroxide solution). If CO₂
• Yellow PbO, brown NO₂ fumes and O₂ gas are is present, lime water turns milky.
formed. Hydrogen Test: Bring a burning splint near the
• NO₂ is brown gas; PbO is yellow solid gas. If hydrogen is present, it burns with a ‘pop’
sound.
, 3.Displacement Reaction: Single Displacement Double Displacement
White precipitate
Zn + 2HCl →
ZnCl₂ + H₂
Zn + H₂SO₄ →
ZnSO₄ + H₂
BaSO₄ confirms presence of sulphate ions.
• Bubbling/fizzing observed due to hydrogen
gas evolution.
• Flask becomes warm →
reaction is exothermic.
Pb(NO₃)₂ (aq) + 2KI (aq) → PbI₂ (s) + 2KNO₃ (aq)
Fe + CuSO₄→ FeSO₄ + Cu colorless sol. colorless sol. yellow ppt. colorless sol.
• Iron nail gets brown coating of copper.
• Blue CuSO₄ solution turns light green AgNO₃ (aq) + NaCl (aq) → AgCl (s) ↓ + NaNO₃ (aq)
(FeSO₄ formation).
• Control test tube shows no change.
• Iron is more reactive than copper 4. Redox Reactions
→
Oxidised: H₂ (H₂ H₂O), Reduced: CuO (CuO → Cu) It is a combination, exothermic and redox reaction
Oxidising agent: CuO, Reducing agent: H₂
(reddish-brown) Black
MnO₂ + 4HCl → MnCl₂ + 2H₂O + Cl₂
→
Oxidised: HCl (Cl⁻ Cl₂), Reduced: MnO₂ (MnO₂
Oxidising agent: MnO₂, Reducing agent: HCl
→ MnCl₂) 2Cu + O₂ → 2CuO
CuO + H₂ → Cu + H₂O
Black CuO turns reddish-brown again on passing hydrogen gas.
FINAL REVISION
REVISION
, CHEMICAL REACTIONS & EQUATIONS
Balanced Chemical Equation: Pb(NO₃)₂ → PbO + NO₂ + O₂ MnO₂ + HCl → MnCl₂ + H₂O + Cl₂
1.Combination Reaction:
→
2Mg + O₂ 2MgO (white powder)
Mg ribbon should be cleaned with sandpaper before burning (removes MgO layer).
• It burns with a dazzling bright white flame.
• It is also an oxidation reaction (Mg gains oxygen).
• The reaction is exothermic (heat and light are produced).
CaO (s) + H₂O (l)→ Ca(OH)₂ (aq) + Heat EXOTHERMIC REACTIONS:
Slaked lime [Ca(OH)₂ solution] is used for whitewashing walls. 1. Burning of Natural Gas (Methane)
It reacts slowly with carbon dioxide (CO₂) from the air. CH₄ (g) + 2O₂ (g)→ CO₂ (g) + 2H₂O (g) + Heat
Calcium carbonate (CaCO₃) forms on the walls after 2–3 days. 2. Decomposition of Vegetable into Compost :
This thin layer of CaCO₃ gives walls a shiny finish. Vegetable waste → Compost (Khad) + Heat
Marble also has the same chemical formula: CaCO₃.
Ca(OH)₂ (aq) + CO₂ (g) → CaCO₃ (s) + H₂O (l) 3. Respiration is an Exothermic Process:
When Excess CO₂ is Passed: the white precipitate of CaCO₃
Reaction:C₆H₁₂O₆ (aq) + 6O₂ (aq) → 6CO₂ (aq) + 6H₂O (l) + Energy
ENDOTHERMIC REACTIONS:
dissolves. It forms soluble calcium hydrogen carbonate.
→
CaCO₃ (s)+CO₂ (g)+H₂O (l) Ca(HCO₃)₂ (aq)
Photosynthesis : 6CO₂ (g) + 6H₂O (l) → C₆H₁₂O₆ (aq) + 6O₂ (g)
(In presence of sunlight and chlorophyll)
, 2.Decomposition Reaction:
Thermal Decomposition Electrolytic decomposition: Photolytic Decomposition:
• Balanced equation: 2H₂O(l) → 2H₂(g) + O₂(g). 2AgCl(s)→ 2Ag(s) + Cl₂(g) (in sunlight)
• FeSO₄·7H₂O (green crystals) first lose water on • Hydrogen is released at the cathode (reduction). • Silver chloride (AgCl) is white in colour.
heating and turn white. • Oxygen is released at the anode (oxidation). • On exposure to sunlight, it turns grey due to
• On strong heating, white FeSO₄ decomposes to • Volume ratio of H₂ : O₂ = 2 : 1. formation of silver (Ag).
form brown Fe₂O₃. • Mass ratio of H₂ : O₂ = 1 : 8. • Chlorine gas (Cl₂) is released.
• Pungent smelling gases SO₂ and SO₃ are evolved • Dilute acid is added to increase conductivity (pure • Silver chloride is photosensitive; hence stored in
water is a poor conductor). dark-coloured bottles.
(cause acid rain).
• Reactions: FeSO₄·7H₂O→ FeSO₄ + 7H₂O • Similar reaction: 2AgBr(s) → 2Ag(s) + Br₂(g) (in
2FeSO₄ → Fe₂O₃ + SO₂ + SO₃ Oxygen Test: When a glowing splint is inserted
sunlight)
• Used in black-and-white photography.
into the gas, it relights, confirming oxygen is
present.
2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂ Carbon dioxide Test: Bubble the gas through
• On heating, lead nitrate decomposes. lime water (calcium hydroxide solution). If CO₂
• Yellow PbO, brown NO₂ fumes and O₂ gas are is present, lime water turns milky.
formed. Hydrogen Test: Bring a burning splint near the
• NO₂ is brown gas; PbO is yellow solid gas. If hydrogen is present, it burns with a ‘pop’
sound.
, 3.Displacement Reaction: Single Displacement Double Displacement
White precipitate
Zn + 2HCl →
ZnCl₂ + H₂
Zn + H₂SO₄ →
ZnSO₄ + H₂
BaSO₄ confirms presence of sulphate ions.
• Bubbling/fizzing observed due to hydrogen
gas evolution.
• Flask becomes warm →
reaction is exothermic.
Pb(NO₃)₂ (aq) + 2KI (aq) → PbI₂ (s) + 2KNO₃ (aq)
Fe + CuSO₄→ FeSO₄ + Cu colorless sol. colorless sol. yellow ppt. colorless sol.
• Iron nail gets brown coating of copper.
• Blue CuSO₄ solution turns light green AgNO₃ (aq) + NaCl (aq) → AgCl (s) ↓ + NaNO₃ (aq)
(FeSO₄ formation).
• Control test tube shows no change.
• Iron is more reactive than copper 4. Redox Reactions
→
Oxidised: H₂ (H₂ H₂O), Reduced: CuO (CuO → Cu) It is a combination, exothermic and redox reaction
Oxidising agent: CuO, Reducing agent: H₂
(reddish-brown) Black
MnO₂ + 4HCl → MnCl₂ + 2H₂O + Cl₂
→
Oxidised: HCl (Cl⁻ Cl₂), Reduced: MnO₂ (MnO₂
Oxidising agent: MnO₂, Reducing agent: HCl
→ MnCl₂) 2Cu + O₂ → 2CuO
CuO + H₂ → Cu + H₂O
Black CuO turns reddish-brown again on passing hydrogen gas.
