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MixturesVA SOL 5.4 K. Benzie
Mixtures Mixtures are a type of matter. They are formed not through chemical changes, but through physical changes. Mixtures contain two or more different substances that are not chemically joined. Though two or more substances are mixed together, each substance in a mixture remains chemically unchanged.
Mixtures • The substances that are combined in a mixture do not have to be evenly spread throughout. • If you had a box of raisin bran and poured it into 4 bowls, would you have the same number of raisins and flakes in each bowl? No! The raisins are not spread evenly throughout the bran flakes.
Mixtures Because mixtures are physically combined, they can be taken apart without a chemical reaction. Think about a bag of party mix. What is your favorite part? Do you pick that out and leave behind the parts you don't like? Party mix is a mixture. When you pick out your favorite parts, you are separating it by hand.
Mixtures • Not all mixtures can be easily separated by hand. Sometimes you might need to use another method to separate the substances. • What could you use to separate sand and water? • What could you use to separate sand and iron filings?
Mixtures • Mixtures can be separated using: • hand separation • filters • screens • magnets (if iron is one of the substances) • evaporation • Can you think of a mixture you would separate using each of the methods?
Mixtures Solutions are a special kind of mixture. In a solution, one or more substances are dissolved into another substance. The substances in a solution are spread evenly throughout. Making a solution does not involve a chemical change, but it does involve a physical change. Kool-aid, lemonade, salt water, and soda are all examples of solutions.
Mixtures Kool-aid is a solution. Sugar and flavored powder are dissolved in water. The first sip of the Kool-aid tastes the same as the last sip because the substances are spread evenly throughout. If they weren't evenly spread, some sips would be watery and some would be too sugary. + = +
Mixtures In a solution, the substance in which another substance dissolves is called the solvent. The substance that dissolves is called the solute. Because water is the solvent for so many solutions, it is often called the universal solvent.
Mixtures • Solutions can involve solids, liquids, and gases. • Lemonade - water, lemon juice, sugar (liquid, liquid, solid) • Soda water - water, carbon dioxide (liquid, gas) • Steel - carbon and iron (solid, solid) • Scented bar soap - soap and perfume (solid, gas)
Mixtures Changing the amount of solute you add to a solution changes the concentration of the solution. A solution with a lot of solute is called a concentrated solution. (Imagine putting 2 packs of hot cocoa mix in one cup of water!) A solution with little solute is called a dilute solution. (Imagine only putting half of one cocoa mix in one cup of water.) When a solution has as much solute as it can hold, it is called a saturated solution. Solutes can be solids, liquids, or gases.
Mixtures Another special kind of mixture is a suspension. A suspension is a kind of mixture that separates if it is left alone for some time. Italian dressing is an example of a suspension. You have to shake it up before you use it because it separates when left alone.
Mixtures Unlike a solution, the particles in a suspension are not spread evenly throughout. The particles in a suspension are much larger than the particles in a solution. This is why they do not dissolve. Mud is another example of a suspension. Over time, the soil will settle to the bottom and the water will be on top.
Mixtures Let’s review! • Mixture - 2 or more substances, physically joined. Substances are not evenly spread throughout. • Mixtures can be separated without a chemical reaction (by hand, filter, screen, evaporation, etc.). • Solution - mixture where one or more substances are dissolved in another. Substances are evenly spread throughout. • Suspension - mixture that will separate if left alone.
