About Matter - NZ Science Class Online

2018 Version Separating Mixtures Junior Science 6aSolutions are made from a solute dissolved in a solvent Solute (salt) Solvent (water) Solution (saltwater) A solution is made up of a solvent and a solute. A solvent is a substance such as water that is able to dissolve a solute. The solvent pulls apart the bonds

that hold the solute particles together and the solute particles diffuse (spread randomly by hitting into each other) throughout the solvent to create a solution. The solution is a mixture with evenly spread solvent and solute particles. These particles can be physically separated by evaporation. 6a Where has the sugar gone? When a solid mixes into a liquid and can no longer be seen it has dissolved. Often the particles of the solute seemed to have disappeared but they are all still present. They are now just in very small particles, too small to be seen by eye.

As a solvent water forms solutions with many different solutes. Solutions are simply mixtures of materials, one of which is a liquid or a gas. The liquid or gas, also called a fluid because it is able to flow. One of the most common solvents is water. All water found in natural sources on Earth, except in rain water or ice, is in the form of a solution such as salt water in the oceans and mineral water in rivers, springs, water and lakes. Minerals from the surrounding rocks are eroded and dissolved into the water. 4 4 6b Dissolving and melting. Both dissolving and melting are physical changes but they involve different processes All Solids will melt into liquids if you apply enough heat energy

Heating adds more kinetic energy to particles Particles will break free from each other to form a liquid Some solids will dissolve into solvents to form a solution, which is a mixture The solid sugar cubes are added to a cup of coffee (a mixture of water and coffee granules) The coffee dissolves the sugar and the particles are spread throughout the solution 6c Everyday solutions Many drinks we purchase are solutions. Most of them are solutions of mainly sugar (solute) and water (solvent) with a small amount of flavouring, colouring

and some minerals mixed in. We do not see the sugar because it is dissolved into the water and becomes to small to see. This means a lot of sugar can be hidden in the liquid and we are unaware of the amount of sugar we take in, even in so-called healthy sports drinks. Ba Kn ck ow gro le un dg d e Saturated solutions The amount of a solid (solute) that can be dissolved into a solvent to form a solution depends on the solubility of the substance. When a solvent can dissolve no more solute then the solution is known as saturated. If any more solute is added after this point then solids crystals begin to form.

Ba Kn ck ow gro le un dg d e Concentration, dilution and saturation. A solution becomes more concentrated as more solute is dissolved into the solvent. When a solvent can dissolve no more solute and extra solute added remains as a solid the solution is said to be saturated. To dilute a solution more solvent is added so there becomes fewer particles of solute dissolved into the solvent as a solution becomes more diluted.

7a Mixtures can be separated by physical processes Mixtures of substances are not chemically bonded (joined) to each other so they can be separated by physical techniques. The state of the various substances in the mixture, such as a liquid and solid or the physical properties of the substances, such as different boiling points will determine which method of separation will be used. Ba Kn ck ow gro

le un dg d e Mixtures are made up of different components Mixtures can be physically separated into different components. A common household example of a mixture could be a cup of white coffee. This mixture is made up of three major components: Milk, coffee and water. Milk itself is a mixture that can be further broken down into other components such as fat, protein, sugar and water

Components of air mixture Ba Kn ck ow gro le un dg d e Common Laboratory equipment Science labs contain equipment that are used to carry out separation of mixtures. You will need to remember the name and how to draw this equipment, using common equipment diagrams. Ba Kn ck ow gro le un

dg d e Drawing equipment in Science In the science lab we often we have to draw the equipment. We use diagrams to show the equipment, which saves us time drawing. The scientific diagrams are recognised world wide. 7a Mixtures can be easily separated physically using methods such as: Filtering Filtering separates an insoluble solid in a mixture from the liquid completely. The solvent molecules (liquid) and any dissolved molecules present in the solution can pass through the filter

paper, which has small holes, while the solid particles cannot because they are to large and stay in the filter paper. The solvent or solution containing dissolved substances passes through the filter paper, is called filtrate. The solid particles that remain on the filter paper are called the residue. Filtering mud, sand and seawater http://slideplayer.com/slide/43857 7c Mixtures can be easily separated physically using methods such as: dissolving When two solid substances are mixed together they can be

separated by dissolving. A solvent such as water can be added if only one of the substances is soluble. For example; if salt is mixed with dirt then adding water will dissolve the salt (which can later be separated by evaporation) and the remaining dirt can be removed from the solution by filtering. The salt becomes the solute and will go through the filter as it is in solution. 7b Mixtures can be easily separated physically using methods such as: Evaporating (by boiling) p://slideplayer.com/slide/10577237/ Evaporating separates a dissolved solid from a liquid. The solvent (liquid) is lost into the surroundings.

The liquid will evaporate but evaporation becomes faster at higher temperatures. The solid remains because it has a higher (often very much higher) boiling point than the liquid. 7d Mixtures can be easily separated physically using methods such as: Decanting Decanting is simply pouring off a liquid without losing any of the more dense substance (usually an insoluble solid) in the bottom of the container. Decanting separates a heavier substance from a lighter one. Chemists are most often after the substance at the BOTTOM of the container.

Original mixture of a solid and liquid Heavier solid is allowed to settle to the bottom The liquid is poured off the top while the solid remains 7f Mixtures can be easily separated physically using methods such as: Magnetism Magnetism can be used to

separate a magnetic substance (such as iron) from a mixture containing non-magnetic substances (such as sulfur or sand). The magnetic substance of the mixture is separated with the help of the magnetic attraction. A magnet is moved over the mixture containing the magnetic substance e.g., iron filings. These get attracted to the magnet. The process is repeated until the magnetic material is completely separated from the mixture. The non-magnetic substance is left behind. http://www.mstworkbooks.co.za/natural- 7e

Mixtures can be easily separated physically using methods such as: Chromatography Chromatography is a method used to separate the various substances in a mixture of dye or ink. Substances of the mixture will differ in how much they "stick" to things: to each other, and to other substances. Some of the substances of the ink will stick more tightly to the paper fibres. They will spend less time in the water as it moves along the paper fibres, and they will not travel very far. Other components of the ink will stick less tightly to the paper fibres. They will spend more time in the water as it moves along the paper fibres, and they will travel further through the paper. 7g Mixtures can be easily separated physically using methods such as: Distillation Distillation is a process of boiling a liquid until it forms a vapour and condensing, then collecting the liquid. The liquid

collected is the distillate. The Liebig Condenser cools the vapour back into liquid. The purpose of distillation is separation of a mixture of two liquids. This is possible if the two substances have different boiling points. The substance with the lower boiling point turns to gas and is collected while the other substance with a higher boiling point remains as a liquid in the flask. http://lookgoodandstudyhard.blogspot.co.nz/2015/12/chemistry-unit-2-experimental- 4 Mixtures can be easily separated physically

Separation technique Property used for separation Magnetic Attraction magnestism Decanting density or solubility Filtration Evaporation solubility, size of particles solubility and boiling point

dissolving solubility Distillation boiling point example magnetic iron can be separated from non-magnetic sulfur using a magnet liquid water can be poured off (decanted) insoluble sand sediment less dense oil can be poured off (decanted) more dense water sand can be separated from a solution of sodium chloride in water by filtration soluble sodium chloride can be separated from water by evaporation

soluble salt can be separated from sand by dissolving into a solvent ethanol can be separated from water by distillation because ethanol has a lower boiling point than water Ba Kn ck ow gro le un dg d e Separation processes can create substances that are useful for us In areas that have a limited amount of fresh water but access to salty sea water a purification machine (as shown to the right)

can be used to separate out the salt and other substances from the pure water that can then be drunk. If we require the salt instead of the water we use the same starting solution of salt water. This time we evaporate off the water in large holding ponds and collect the salt deposits that remain. 5aSurvival with a solar sill making pure water from salty water Clea n wat Salty er water With a few pieces of

equipment a solar sill can be made to produce clean drinking water. A hole must be dug with a container of the salty water placed at the bottom. Another collecting container sits on top with a straw leading out of it for drinking. A plastic sheet covers the hole and is secured with rocks. A rock weight is placed on the sheet. Water is evapourated from the salty water, condenses on the plastic sheet and drips into the collecting container.

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