TPE Revision_Chemistry notes

1 © Copyrights to Thang Pang Ern 2019 GCE ‘O’ Level Chemistry Revision Chapter 1 – Kinetic Particle Theory Gases Gases are easily compressed as the volume of gas particles is negligible compared to the volume occupied by the gas. Chapter 2 – Measurement and Experimental Techniques Apparatuses for Measurement The accuracies of apparatuses used for measurement in ascending order are beaker, graduated measuring cylinder, burette then pipette. Collection of Gases The collection of poisonous gases (e.g. chlorine) when carrying out downward delivery should be carried out in a fume cupboard. Method Suitability Examples Displacement of water  Insoluble or slightly soluble in water  Hydrogen  Carbon dioxide  Oxygen Downward delivery  Soluble in water  Denser than air  Hydrogen chloride  Chlorine Upward delivery  Soluble in water  Less dense than air  Ammonia Drying of Gases We can dry a gas by passing it through a drying agent. Using conc. sulfuric acid to dry ammonia is unsuitable as the sulfuric acid will react with the ammonia to produce ammonium sulfate. Drying agent Suitability and examples Conc. sulfuric acid  Most gases Quicklime  Ammonia Calcium chloride  Most gases

2 © Copyrights to Thang Pang Ern 2019 Chapter 3 – Separation and Purification Desert Survival Kit The desert survival kit question makes use of distillation. Chapter 6 – Ionic Bonding Ionic bonding is b etween metallic and non -metallic elements and it refers to the t ransfer of electrons from one element to another. Ionic compounds are solids at room temperature. Melting and Boiling Points Ionic compounds have high melting and boiling points. Strong electrostatic forces between the positive and negative ions which are arranged in a giant crystal lattice. It requires much energy in order to separate the ions. Electrical Conductivity Solid ionic compounds do not conduct electricity since the ions are held firmly in place, indicating the absence of free-moving ions to conduct electricity.

3 © Copyrights to Thang Pang Ern 2019 Ionic compounds only conduct electricity when dissolved in a solution or in the molten state. When an ionic compound melts or when it’s dissolved in a solution, the charged ions are free to move. When an electric current passes through, solutions of ionic compounds can be decomposed into their individual elements. Chapter 7 – Covalent and Metallic Bonding Covalent Bonding Covalent bonding is between non-metallic and non-metallic elements and it refers to the sharing of electrons between elements . Covalent compounds are u sually gaseous or liquids at room temperature. Diamond – Melting and Boiling Points Diamond has high melting and boiling points. 1 carbon atom is bonded to 4 other carbon atoms, making it having a tetrahedral structure. Much energy is required in order to separate the atoms which are connected by strong cova