Coaching Centre
Chapter 5: Mixtures Notes
Pure substances and mixtures, solutions, colloids and suspensions, dissolving and solubility, and the techniques used to separate mixtures: sieving, magnets, decanting, filtering, centrifuging, evaporation, crystallisation, distillation and chromatography, with real uses from water treatment to forensic science.
Sections
-
5A Pure substances and mixtures Mastered
What chemists mean by pure, elements and compounds as pure substances, mixtures as substances that are not chemically joined, particle pictures of each, and alloys such as brass and carat gold.
-
5B Solutions, colloids and suspensions Mastered
The three main types of mixture by particle size: solutions, colloids and suspensions. How to tell them apart with a torch beam (the Tyndall effect), by leaving them to stand and by filtering. Emulsions, foams, gels and aerosols, and emulsifiers.
-
5C Solutions and solubility Mastered
Solute, solvent and solution, dissolving at the particle level, soluble and insoluble substances, water as the universal solvent, concentrated and dilute solutions, saturated solutions, solubility curves and how temperature affects solubility.
-
5D Separating by size, density and magnetism Mastered
Choosing a separation method by the property that differs: hand sorting, sieving and filtering (particle size), magnetic separation, decanting, sedimentation and flotation (density), centrifuging, and electrostatic separation. Setting up a filtration correctly.
-
5E Evaporation, crystallisation and distillation Mastered
Using heat to separate solutions: evaporation to recover a dissolved solid, crystallisation to grow pure crystals, and distillation to collect the solvent as well. Separating salt from sand step by step, how a condenser works, and fractional distillation.
-
5F Chromatography Mastered
How paper chromatography separates the dyes in inks and food colourings, setting up a chromatogram, the start line and solvent front, calculating Rf values, and how forensic scientists, sports drug testers and food chemists use chromatography.
-
5G Separation in the real world Mastered
How Sydney's drinking water is treated, desalination by reverse osmosis at Kurnell, sewage and water recycling, separating blood, kidney dialysis, mining and oil spills. Planning a multi-step separation and weighing up the costs and benefits of separation technologies.
-
5H Mixtures review Mastered
A summary of the whole Mixtures chapter, key words, and a mixed test covering pure substances, solutions, colloids and suspensions, solubility, separation methods, chromatography and water treatment.