Mixtures Outcomes

Mixtures Identify the difference between pure and impure substances. Difference between pure and impure substances: Pure substances -made up of one type of particle Impure substances - made up of a mixtures of two or more types of particle 2.  Using examples, define the terms solute, solvent and solution. Solute - substance which dissolves in another substance (solvent) - e.g. salt in salt water Solvent - substance in which another substance is dissolved in (solute) - e.g water in saltwater Solution - clear substance where a substance is dissolved in another - e.g. salt water 3. Describe the general properties of solutions.     Solutions are: Clear - able to be seen through Homogeneous - substance is evenly mixed in another Coloured or colourless Contain a substance in which is dissolved in another 4. Describe the importance of water as a solvent that enables reactions to occur in living things.     Water is important for life as: It dissolves chemicals that carry out reactions Chemicals must be fast, which only happens when dissolved in water 5. Define the strength of a solution in the terms of dilute, concentrated and saturated.     Strength of a solutions: Dilute - little solute dissolved in solvent (e.g tsp of sugar in filled pool) Concentrated - large amount of solute dissolved in solvent (e.g. 10 tsp of sugar in cup of tea) Saturated - so much solute dissolved in solvent that no more solute can dissolve (e.g. 19 tsp of sugar in cup of tea) 6.  Define suspension, giving examples of solid/liquid, solid/gas and liquid/liquid suspensions.      Suspension - mixture where a substance is dispersed, but not dissolved, in another substance Examples Solid/liquid - Sand in water Sold/gas - Dust in air Liquid/liquid - Oil and water 7.  Colloid - very fine particles dispersed, but not dissolved in another substance Emulsion - Liquid/liquid colloid(e.g milk, mayonnaise) Foam - Gas/liquid colloid(e.g whipped cream) Gel - Liquid/solid colloid(e.g. jelly) Sol - Solid/liquid colloid(e.g. Milk, blood) 

8.  Identify and describe methods used to separate suspensions, including decanting, sieving, centrifugation and filtration. Separation Technique(Suspensions) - Description Decanting - Pouring off top layer of settled suspension Sieving - Using sieve with small-medium sized holes to separate different sized particles in suspension Centrifugation - Using device to quickly spin an unsettled suspension to settle it Filtration - Using a filter with very fine pores to separate different sized substances in a mixture 9.  Identify the limitations and benefits of decanting, sieving, centrifugation and filtration. Separation Technique(Suspension) - Limitations - Benefits Decanting - Can only be used on settled suspensions - Simple and easy Sieving - Can only be used on different sized substances where only one can fit in holes - Simple and easy Centrifugation - Hard and lengthy process, can only be used on unsettled suspensions - One of few ways to settle out suspension that may never settle Filtration - Can only be used on different sized substances where only one can fit in holes - Simple and easy, useful when substance is trapped in another   10. Identify everyday examples where decanting, sieving, filtration and centrifugation can be used. Separation Technique(Suspensions) - Examples Decanting Pour off water from vegetables Pour wine into container, leaving behind sediment Sieving Sieve used to ensure only rocks of correct size go in crusher To grade soil by size for classification Filtration Separate coffee grounds from filter coffee Separate dust from air using mask filter Centrifugation Spin cycle of washing machine Salad spinners to dry washed lettuce 11. Identify and describe methods used to separate solutions, including evaporation, condensation, crystallisation and distillation. Separation Technique(Solutions) - Description Evaporation Heat is used to evaporate liquid solvent, leaving behind solute Condensation After solvent is evaporated, it can be condensed so the solvent isn’t lost Crystallisation As solvent evaporates, solution becomes so concentrated that solute forms crystals Distillation Evaporation used to separate solvent from solute, then retrieved using condensation   12. Identify everyday examples where evaporation and distillation can be used. Separation Technique(Solutions) - Examples Evaporation Clothes on drying rack dry from evaporation After swimming in sea, water on skin evaporates, leaving salt behind Distillation Separating crude oil into petrol, diesel etc. Water cycle(water from sources evaporates, condenses into clouds)   13.  Identify and describe methods used to separate solids, including centrifugation, electrostatic, sieving and magnetic attraction. Separation Technique(Solids) Description Centrifugation Suspension is spun around at high speeds, settling out solid in liquid Electrostatic Particles of different polarity are separated in a solid Sieving Two solids are put through a sieve - one fits in holes, the other doesn’t Magnetic Attraction Magnet attracts magnetic substance away from non-magnetic substances 14. Identify some examples where chromatography can be used. Chromatography Examples Water dissolves dye in ink, and carries different colours up the paper Can be used to find out what is in oil and gas Can be used to find drugs in urine 15. Using examples, describe the separation process of adsorption. Adsorption - components which stick to surface, but not go in surface(adsorbate) onto a solid surface (adsorbent), separating mixture. Examples When water molecules adsorb to windows, making it misty When paint adsorbs to a painting surface

16. Identify solids in suspension and solutes dissolved in different water samples(i.e., impure water samples) Solids in Suspension: Seawater - sand suspended in seawater Rivers and lakes - fish, yabbies, bacteria and dirt suspended in river/lake water Solutes dissolved in: Seawater/Rivers/Lakes - oxygen dissolved in seawater Pools - chlorine and other treatments in water 17. List types of potable water sources including the main sources of water for the local area. Potable Water Sources Rivers Lakes Groundwater Local Area Source Sydney - Most water comes from Warragamba Dam Some comes from the desalination plant in Kurnell 18. Explain the need for the process of desalination and identify the use of desalination in Australia. Desalination must be used as: Australia is in drought, and needs the potable water it can get However, desalination is rarely used in Australia because of the big cost. 19. Explain the process of water treatment including the use of additives. Five steps of water treatment: Flocculation - fine solid particles are removed. Outside chemicals (flocculants) may be used to clump together fine particles, making it easier to remove Filtration - water pumped through filters to remove remaining particles Sterilisation - chlorine is added to kill microorganisms in water Balancing pH - the measure of acidity(pH) is changed so water is not acidic nor alkaline Fluoridation - fluoride is added to reduce chance of tooth decay