Mixtures Outcomes

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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)

Solution, Suspension and Colloid Outcomes - Mixtures

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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

Insoluble Mixtures Separation Techniques Outcomes

Solutions Separation Techniques Outcomes

Other Separation Techniques Outcomes

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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

Water as a Solvent Outcomes