pure chem notes

CHAPTER 1 Apparutus : ● Pipette : fixed volumes, 10.0cm³ or 25.0cm³ ● Volumetric flask : larger fixed volumes, 100cm³ or 250cm³ ● Measuring cylinder : nearest 0.5cm³ ● Burette : nearest 0.05cm³ Method for collecting gases : COLLECTING METHOD SOLUBILITY OF GAS IN WATER DENSITY OF GAS EXAMPLES Water displacement insoluble , slightly soluble Density does not affect gas collection Hydrogen Oxygen Carbon dioxide Downward delivery soluble/insoluble Denser than air Chlorine Hydrogen chloride Sulfur dioxide Upward delivery soluble/insoluble Less dense than air Ammonia Method for drying gases : DRYING AGENT EXAMPLES NOTES Concentrated sulfuric acid Most gases, chlorine & hydrogen chlorine Not suitable for gases which react with sulfuric acid (e.g. ammonia) Quicklime (calcium oxide) Ammonia Calcium oxides absorbs moisture & CO₂, freshly heated before use. Cannot be used to dry gases which with calcium dioxide ( carbon dioxide ) Fused calcium chloride Hydrogen. Nitrogen, CO₂ Calcium chloride readily absorbs moisture from the air, freshly heated before use. Cannot be used to dry gases which react with calcium chloride(ammonia)

Separate techniques : Type of mixture SOLID–SOLID MIXTURE SOLID–LIQUID MIXTURE LIQUID–LIQUID MIXTURE Magnetic attraction Filtration Separating Funnel Sieving Evaporation to dryness Chromatography Using suitable solvents Crystallisation Fractional distillation Sublimation Simple distillation CHAPTER 2 Affecting rate of diffusion : Conditions Rate of diffusion Reason Increase ↑ in temperature Increase ↑ More ↑ thermal energy is converted to KE of the particles Increase ↑ in particle mass Decrease ↓ Higher ↑mass require more ↑ KE to move at same speed

CHAPTER 3 Subatomic particles : SUB-ATOMIC PARTICLES RELATIVE MASS RELATIVE CHARGE LOCATION IN THE ATOM Proton 1 +1 Nucleus Neutron 1 0 Nucleus Electron 1/1840 -1 Electron shell CHAPTER 4 Types of chemical bonding : 1. Ionic bonding [ NM + M ] - ↑ Melting point, ↑boiling point - Conduct electricity in MOLTEN & AQUEOUS - Soluble ✓ in water, insoluble ✗in organic solvents - Hard but brittle 2. Covalent bonding [ NM + NM ] - ↓ Melting point, ↓boiling point - CANNOT conduct electricity at any state - insoluble ✗ in water, soluble ✓in organic solvents 3. Metallic bonding [ M + M ] - ↑ Melting point, ↑boiling point - Good conductors of electricity & heat due to SEA OF DELOCALISED ELECTRONS - insoluble ✗in water & organic solvents

CHAPTER 5 Giant ionic crystal lattices : - ↑ Melting point, ↑boiling point - Conduct electricity in MOLTEN & AQUEOUS - Solids at room temperature - Usually soluble ✓ in water, insoluble ✗in organic solvents Types of giant covalent structures/macromolecules : 1. Diamond [ tetrahedral — 1 C atom to 4 C atom ] - Extremely ↑ Melting point, ↑boiling point - CANNOT conduct electricity - Very hard - insoluble ✗in water & organic solvents 2. Graphite [ 1 C atom to 3 C atom ] - ↑ Melting point, ↑boiling point - CAN conduct electricity - Soft & slippery - insoluble ✗ in water & organic solvents 3. Macromolecules - ↓ Melting point, ↓boiling point - CANNOT conduct electricity in any state - insoluble ✗ in water, soluble ✓in organic solvents Giant metallic lattices : 1. Elemental ( regular lattice ) - ↑ Melting point, ↑boiling point - CAN conduct electricity in all states - Solids at room temperature - insoluble ✗ - Malleable & ductile

2. Alloys ( irregular lattices ) - ↑ Melting point, ↑boiling point - CAN conduct electricity in all states - Solids at room temperature - insoluble ✗ - Harder and stronger than pure metals CHAPTER 6 Common polyatomic ions : Name of polyatomic ion Formula of ion Ammonium NH₄⁺ Hydroxide OH⁻ Nitrate NO₃⁻ Sulfate SO₄²⁻ Carbonate CO₃²⁻ Phosphate PO₄³⁻

CHAPTER 7 △△ △△

△ Percentage yield : % yield = x 100% 𝑎𝑐𝑡𝑢𝑎𝑙 𝑦𝑖𝑒𝑙𝑑 𝑡ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑦𝑖𝑒𝑙𝑑 Percentage purity : % purity = x 100% 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑝𝑢𝑟𝑒 𝑠𝑢𝑏𝑠𝑡𝑎𝑛𝑐𝑒 𝑝𝑟𝑒𝑠𝑒𝑛𝑡 𝑖𝑛 𝑠𝑎𝑚𝑝𝑙𝑒 𝑡𝑜𝑡𝑎𝑙 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑖𝑚𝑝𝑢𝑟𝑒 𝑠𝑎𝑚𝑝𝑙𝑒 Empirical formula : n = 𝑀ᵣ 𝑜𝑓 𝑐𝑜𝑚𝑝𝑜𝑢𝑛𝑑 𝑀ᵣ 𝑓𝑟𝑜𝑚 𝑒𝑚𝑝𝑖𝑟𝑖𝑐𝑎𝑙 𝑓𝑜𝑟𝑚𝑢𝑙𝑎 CHAPTER 8 Reactions : 1. Acid + metal →salt + hydrogen 2. base/alkali + acid →salt + water 3. Acid + carbonate → salt + water + CO₂ 4. Alkali + ammonium salt →salt + water +ammonia

Types of acids/base/alkalis : 1. Acid Stong acid = completely ionised Weak acid = partially ionised - Hydrochloric acid [ HCl ] - Ethanoic acid [ CH₃COOH ] - Nitric acid [ HNO₃ ] - Sulfuric acid [ H₂SO₄ ] 2. Bases - Sodium hydroxide [ Na₂O ] - Zinc oxide [ ZnO ] - Copper(II) oxide [ CuO ] - Magnesium hydroxide [ Mg(OH)₂ ] - Aluminium hydroxide [ Al(OH)₃ ] 3. Alkalis - Sodium hydroxide [ NaOH ] - Potassium hydroxide [ KOH ] - Calcium hydroxide [ Ca(OH)₂ ] - Ammonia [ NH₃ ] Colour changes of some indicators : INDICATOR COLOUR IN ACIDIC SOLUTION pH RANGE AT WHICH INDICATOR CHANGES COLOUR COLOUR IN ALKALINE SOLUTION Methyl orange Red 3-5 Yellow Screened methyl orange Violet 3-5 Green Litmus Red 5-8 Blue Thymolphthalein Colourless 9-10.5 Blue

Oxides of metals : 1. Basic oxides ( reacts with acids ) - Cher ⇒ copper(II) oxide [ CuO ] - Chong ⇒ calcium oxide [ CaO ] - Mafan ⇒ magnesium oxide [ MgO ] 2. Amphoteric oxides ( reacts with acids & alkalis ) - Z ⇒ zinc oxide [ ZnO ] - A ⇒ aluminium oxide [ Al₂O₃ ] - P ⇒ lead(II) oxide [ PbO ] Oxides of non-metals : 3. Acidic oxides ( reacts with alkalis ) - Criminals ⇒ carbon dioxide [ CO₂ ] - Stay ⇒ sulfur trioxide [ SO₃ ] in - Prison ⇒ phosphate(V) oxide [ P₄O₁₀ ] 4. Basic oxides ( do not react with acids & alkalis ) - NO ⇒ nitric oxide [ NO ] - HO ⇒ water [ H₂O ] - CO ⇒ carbon monoxide [ CO ]

CHAPTER 9 Solubility of salts : Soluble salts Insoluble salts All sodium salts All potassium salts All ammonium salts All nitrates All chlorides All sulfates Sodium carbonate, Na₂CO₃ Potassium carbonate, K₂CO₃ Ammonium carbonate, (NH₄)₂CO₃ Method for preparation of salts : 1. Adding in excess - Insoluble + soluble →soluble 2. Titration - soluble + soluble →soluble 3. Precipitation - soluble + soluble →insoluble Silver chloride, AgCl lead(II) chloride, PbCl₂ Barium sulfate, BaSO₄ lead(II) sulfate, PbSO₄ Calcium sulfate, CaSO₄ All carbonates