Chemistry

Apparatus and measurements Choose apparatus that measures the quantity needed with suitable precision. Quantity Apparatus Use and limitation Time Stopwatch Measures elapsed time; reaction start and stop can be judged inconsistently. Temperature Thermometer Measures temperature; read at eye level and allow the reading to stabilise. Mass Balance Measures mass; zero it before use and avoid drafts or spills. Liquid volume Burette Delivers variable, accurately measured volumes, especially in titrations. Liquid volume Volumetric pipette Transfers one fixed, accurate volume. Liquid volume Measuring cylinder Measures a range of volumes quickly, but less precisely than a pipette or burette. Gas volume Gas syringe Collects and measures gas directly; check connections for leaks. A measuring cylinder is convenient for approximate volumes. Use a pipette and burette when accurate solution volumes matter. Read liquid levels at eye level, using the bottom of the meniscus for colourless liquids. ...

Organic chemistry studies compounds containing carbon. This guide combines Core and Supplement (Extended) requirements for syllabus topic 11.

Chemistry of the environment Water tests Anhydrous cobalt(II) chloride is blue. It turns pink when water is present. Anhydrous copper(II) sulfate is white. It turns blue when water is present. Purity A pure substance has a sharp melting point and boiling point. Impurities usually change and broaden these values. Distilled water is used to avoid dissolved impurities interfering with an experiment. Natural water Natural water may contain dissolved oxygen, metal compounds, plastics, sewage, microbes, nitrates, and phosphates. Dissolved oxygen supports aquatic life. ...

Comprehensive guide covering the chemical and physical properties of metals, reactivity, extraction, and corrosion.

Structure and position The Periodic Table arranges elements in order of increasing proton number. Horizontal rows are periods; vertical columns are groups. Elements in the same group have similar chemical properties because they have the same number of outer-shell electrons. Across a period, metallic character generally decreases and non-metallic character increases. Position predicts electronic configuration, ion charge, reactivity, and physical properties. Group I atoms lose one outer electron to form $+1$ ions; Group VII atoms gain one electron to form $-1$ ions, because both processes produce a full outer shell. ...