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 - CA