6092 O-Level Chemistry Complete Notes (Ch 1-22) Version 1

CAMBRIDGE O-LEVEL · CHEMISTRY 6092 O-Level Chemistry O-Level Chemistry Complete Personalised Revision Notes — Chapters 1 to 22 Compiled and structured personal revision notes, covering the full O-Level Chemistry syllabus from Experimental Chemistry through to Maintaining Air Quality, for end-to-end self-study. H C cyclohexadienyl radical

Table of Contents Table of Contents ◯ The Periodic Table of Elements (reference chart) 3 1 Experimental Chemistry 4 2 Kinetic Particle Theory 11 3 Atomic Structure 15 4 Chemical Bonding – Ionic Bonding 20 5 Structure and Properties of Materials – Covalent & Metallic Bonding 24 6 Chemical Formulae, Equations & Stoichiometry 31 7 The Mole Concept 33 8 Acids and Bases 38 9 Salts 44 10 Ammonia 46 11 Qualitative Analysis 48 12 Oxidation and Reduction 52 13 Electrochemistry 55 14 The Periodic Table 59 15 The Reactivity Series (Metals) 64 16 Chemical Energetics 68 17 Rate of Reaction 71 18 Fuels and Crude Oil 73 19 Hydrocarbons 77 20 Alcohols, Carboxylic Acids & Esters 82 21 Polymers 87 22 Maintaining Air Quality 90 ✦ Appendix A — Key Definitions 95 ✦ Appendix B — Complete Equation Reference 107

Chapter 1: Experimental Chemistry Chapter 1: Experimental Chemistry Measurement, gas collection/drying, separation techniques, and purity 1.1 | Measurement of Physical Quantities 1.1 | Measurement of Physical Quantities Measuring Time Measuring Time A stopwatch is used to measure time. The SI unit for time is the second (s) second (s) ; minutes (min) and hours (h) may also be used. Depending on the type of digital stopwatch, readings can be taken to 2 decimal places (e.g. 20.01 s). Table 1.1.1 — Precision and uncertainty of digital stopwatches Precision / s Uncertainty / s D.P. Example reading / s 0.1 ±0.1 1 28.1 0.01 ±0.01 2 28.00, 28.11 Ⓘ Ⓘ NOTE — PRECISION VS UNCERTAINTY Precision is set by the smallest division on the instrument. Uncertainty of measurement is the range within which the true value could lie. If a stopwatch reading of 28.00 s has an uncertainty of ±0.01 s, the true value lies between 27.99 s and 28.01 s. Measuring Temperature Measuring Temperature A thermometer (alcohol or mercury) is used to measure temperature, read to the nearest 0.5°C. The SI unit is the kelvin (K) kelvin (K) ; degrees Celsius (°C) is also commonly used (K = °C + 273). A datalogger connected to a temperature sensor datalogger connected to a temperature sensor can also be used. Advantages over a thermometer: More accurate than an alcohol/mercury thermometer Can record data continuously over a period of time Saves data digitally, which can be used to plot graphs/charts Table 1.1.2 — Precision and uncertainty of laboratory thermometers Precision / °C Uncertainty / °C D.P. Example / °C 1 ±0.5 1 23.0, 23.5 Measuring Length Measuring Length A metre rule or measuring tape is used. SI unit: metre (m) metre (m) . Other units: mm, cm, dm. Table 1.1.3 — Precision and uncertainty of a metre rule Precision / mm Uncertainty / mm D.P. Example / mm 1 ±0.5 1 20.5 Measuring Mass Measuring Mass An electronic (mass) balance is used, recorded to the nearest 0.001 g depending on model. SI unit: kilogram (kg) kilogram (kg) ; grams (g) and milligrams (mg) also used. Table 1.1.4 — Precision and uncertainty of an electronic balance Precision / g Uncertainty / g D.P. Example / g 0.001 ±0.001 3 2.253

Measuring Volume of Liquids/Solutions Measuring Volume of Liquids/Solutions Table 1.1.5 — Instruments used to measure volume of liquids Apparatus Precision / cm 3 Uncertainty / cm 3 D.P. Primary use Measuring cylinder 1 ±0.5 1 Approximate volumes of liquids/solutions Pipette — ±0.1 1 Accurate, fixed volumes (e.g. 25.0, 10.0 cm 3 ) Burette 0.1 ±0.05 2 Very precise, variable volumes (e.g. 25.45 cm 3 ) Volumetric flask — — — Accurate, large fixed volumes (e.g. 100, 250 cm 3 ) Ⓘ Ⓘ NOTE — PARALLAX ERROR When reading a burette or measuring cylinder, position your eye level with the meniscus to avoid parallax error. For coloured liquids, read from the top of the meniscus if the bottom cannot be seen. To measure the volume of a gas gas , a gas syringe gas syringe is used (typically up to 100 cm 3 ). 1.2 | Collection and Drying of Gases 1.2 | Collection and Drying of Gases Water displacement Downward delivery Upward delivery Gas syringe Fig 1.2.1–1.2.4. Fig 1.2.1–1.2.4. The four main methods of collecting gases, chosen by density and water-solubility of the gas. Table 1.2.1 — Methods of collecting gases Method Used for Description Example gases Water displacement (downward displacement of water) Insoluble/slightly soluble gases (density irrelevant) Gas is bubbled into an inverted, water-filled test tube/gas jar; the gas displaces water as it collects O 2 , H 2 , CO 2 Downward delivery (upward displacement of air) Gases denser than air Gas sinks into the (unsealed) gas jar and pushes air out from the top Cl 2 , HCl, SO 2 , NO 2 Upward delivery (downward displacement of air) Gases less dense than air Gas rises into the (unsealed) gas jar and pushes air out from the bottom NH 3 , H 2 Gas syringe Any gas — also measures volume Gas produced pushes the plunger outward; volume read directly off the syringe Any Ⓘ Ⓘ NOTE The approximate relative molecular mass (M r ) of air is 29. Gases with M r > 29 are collected by downward delivery; gases with M r < 29 by upward delivery.

Table 1.2.2 — Density, solubility and collection methods of common gases Gas Density vs air Solubility in water Method(s) of collection Hydrogen, H 2 Less dense Insoluble Upward delivery & water displacement Ammonia, NH 3 Less dense Highly soluble Upward delivery Oxygen, O 2 Slightly denser Slightly soluble Downward delivery & water displacement Hydrogen chloride, HCl Denser Highly soluble Downward delivery Carbon dioxide, CO 2 Denser Slightly soluble Downward delivery & water displacement Nitrogen dioxide, NO 2 Denser Highly soluble Downward delivery Sulfur dioxide, SO 2 Denser Highly soluble Downward delivery Chlorine, Cl 2 Denser Highly soluble Downward delivery Drying Gases Drying Gases Gases are classified as neutral neutral (O 2 , N 2 , H 2 ), acidic acidic (HCl, CO 2 , NO 2 , SO 2 ) or alkaline alkaline (NH 3 ) — a drying agent must not react with the gas being dried. Table 1.2.3 — Drying agents Drying agent Suitable for Not suitable for Reason unsuitable Concentrated sulfuric acid Neutral, acidic gases Alkaline gases (NH 3 ) Reacts with NH 3 (neutralisation/acid-base reaction) Quicklime, CaO (freshly heated) Neutral, alkaline gases Acidic gases Reacts with acidic gases (neutralisation) Fused (anhydrous) calcium chloride (freshly heated) Neutral, acidic gases NH 3 Anhydrous CaCl 2 reacts with NH 3 to form a complex, CaCl 2 .8NH 3 Fig 1.2.5. Fig 1.2.5. Drying a gas using concentrated sulfuric acid. Fig 1.2.6. Fig 1.2.6. Drying a gas using quicklime (calcium oxide).

Fig 1.2.7. Fig 1.2.7. Drying a gas using fused (anhydrous) calcium chloride. KEY QNS 1.2.1 — DRYING HYDROGEN Q. Q. Concentrated sulfuric acid should not be used to dry hydrogen gas even though hydrogen is neutral. Suggest why. A. A. When concentrated sulfuric acid absorbs water vapour from the gas, a large amount of heat is given out. This heat could ignite the hydrogen gas, which is highly flammable. Ⓘ Ⓘ NOTE Quicklime (CaO) absorbs both moisture and CO 2 from air and so must be freshly heated (to drive off absorbed water/CO 2 ) immediately before use. The same applies to fused calcium chloride, which readily absorbs moisture from the air. 1.3 | How Are Substances in Mixtures Separated? 1.3 | How Are Substances in Mixtures Separated? DEFINITION 1.3.1 — MIXTURE A mixture is a substance made up of two or more substances that are not chemically combined (i.e. physically combined, in no fixed ratio). DEFINITION 1.3.2 — PURE SUBSTANCE A pure substance is made up of only one element or compound; it is not mixed with any other substance. Table 1.3.1 — Methods of separating different types of mixtures Solid–Solid Solid–Liq