© OUP: To be used solely in purchaser’s school or college A pure substance contains just one type of particle. A mixture contains at least two different types of particle. It’s a trick question – they’re all mixtures! Do you know why? A liquid can be pure or a mixture. 7H Mixtures and solutions - Is it pure or is it a mixture? Which of these liquids is a mixture?

© OUP: To be used solely in purchaser’s school or college solid – no longer visible liquid – may change colour A solid that dissolves in water is soluble. solid – still visible liquid – no colour change A solid that does not dissolve in water is insoluble. Does the solid dissolve? YESNO 7H Mixtures and solutions - Does the solid dissolve? solid + liquid mixture

© OUP: To be used solely in purchaser’s school or college When a solid dissolves in a liquid it forms a special type of mixture called a solution. 7H Mixtures and solutions - What’s the solution? solvent solvent - the liquid/substance that does the dissolving solvent solvent - the liquid/substance that does the dissolving solute solute - the substance being dissolved (a solution can have more than one solute but only one solvent) solvent solute and solution - formed when the solvent and solute mix together solution Click on the beaker for some important solution words beginning with “s”!

© OUP: To be used solely in purchaser’s school or college How can you separate the solvent from the solids dissolved in a solution? Distillation involves three stages: The best method to separate and collect the solvent from a solution is distillation. boiling condensing collecting 7H Separation techniques – Distillation

© OUP: To be used solely in purchaser’s school or college Where in the distillation equipment do boiling, condensing and collecting take place? 7H Separation techniques – Distillation water in water out boiling thermometer heat heat mat gas cools and condenses Liebig condenser gas turned back to a liquid one of liquids in mixture liquid boils off flask with mixture

© OUP: To be used solely in purchaser’s school or college water in water out Cold water enters the outer tube at the bottom and warm water leaves the outer tube at the top. Why does this happen? The most important piece of kit for distillation is the Liebig condenser. 7H Separation techniques – Distillation 2. Cold water in the outer tube cools the hot gas, which condenses to become a liquid. 3. The liquid is collected at the bottom. 1. Hot gas passes down the inner tube.

© OUP: To be used solely in purchaser’s school or college 2. Do you want to collect the solid (solute) or the liquid (solvent) from the solution? 1. Is the solid soluble or insoluble? 7H Separation techniques - Summary The choice of separation technique depends on two things:

© OUP: To be used solely in purchaser’s school or college Match the correct description to the separation technique. Name 1 Evaporation… 2 Filtration… 3 Chromatography… 4 Distillation… Description A…is used to separate small amounts of two or more solids which are soluble in the same solvent. B…is used to separate a soluble solid from the liquid to obtain the solute. C…is used to separate a soluble solid and a liquid to obtain the solvent. D…is used to separate an insoluble solid from a liquid. 7H Separation techniques - Summary