Mixtures Chapter 9

Standard: GLE 0807.9.4 Distinguish among elements, compounds, and mixtures.

What are we going to learn? I CAN: Describe three properties of mixtures. Describe four methods of separating parts of a mixture. Analyze a solution in terms of its solute and solvent. Explain how concentration affects a solution. Describe the particles in a suspension. Explain how a colloid differs from a solution and a suspension.

What do we already know? Element = a pure substance (it is in its simplest form and all particles are the same) Compound = two or more elements that have combined because of a chemical reaction Elements can not be broken down Compounds can only be broken down by a chemical change

What is a mixture? Mixture = a combination of two or more substances that are not chemically combined No chemical change occurs Each substance keeps it identity Example: Pizza

Describe Three Properties of Mixtures: Components of a mixture can be easily separated Components each keep original properties Proportion of components in a mixture is specific

Four Methods of Separating Mixtures Physically separate it Distillation – separation based on boiling point Magnet – some part of a mixture may be magnetic Centrifuge – separation by spinning

Four Methods of Separating Mixtures – physical means Don’t like the toppings on your pizza? Just remove them! This is a physical change. Evaporation of saltwater

Four Methods of Separating Mixtures - Distillation Separates mixtures based on boiling points of components Separates pure water from saltwater, crude oil into gasoline and kerosene

Four Methods of Separating Mixtures - Magnet A magnet can be used to separate a mixture of iron and aluminum. (elements) Iron is attracted to the magnet but aluminum is not. https://www.youtube.com/watch ?v=anaCLlmBSzg

Four Methods of Separating Mixtures - Centrifuge The different parts of blood are separated with a centrifuge. (plasma, red blood cells) Separates mixtures by densities of components.

Analyze Solutions – solvent and solute Solution = a mixture that appears to be a single substance Composed of two or more substances that are evenly distributed Example: Kool Aid Within a solution: Solute = what is being dissolved (sugar in kool aid) Solvent = what is doing the dissolving (water in kool aid)

Analyze Solutions – solvent and solute Process in which particles of a substance separate and spread evenly throughout a mixture = dissolving A solute must be soluble, or able to dissolve, in the solvent A substance that is insoluble, or unable to dissolve, forms a mixture that is not a solution.

Analyze Solutions – solvent and solute Salt water is a solution. Salt is soluble in water, so salt dissolves in water. Salt = solute Water = solvent When two liquids or gases form a solution, substance present in largest amount is solvent.

Analyze Solutions (continued) Liquid in liquid (antifreeze – alcohol in water) Some solutions can be different states, not all are liquid Solid in liquid (salt water) Solid in solid(brass alloy – zinc dissolved in copper; steel alloy – carbon, other elements in iron) Gas in Gas (dry air – oxygen in nitrogen) Gas in liquid (soft drinks – CO2 in water)

Solution or Not A Solution? Sugar and Sand…solution or not a solution? NOT A SOLUTION...grains can be physically separated

Solution or Not A Solution? Diet Soda…Solution or Not A Solution? SOLUTION...gas is dissolved in liquid

Solution or Not A Solution? Air…Solution or Not A Solution? SOLUTION...gases are dissolved in other gases

Solution or Not A Solution? Water and Oil…Solution or Not A Solution? NOT A SOLUTION...the liquids can be physically separated

Solution or Not A Solution? Chocolate Chip Cookie…Solution or Not A Solution? NOT A SOLUTION...the chips can be physically separated from the cookie

How Concentration Affects a Solution Concentration = the amount of a particular substance in a given quantity of a mixture (how much solute dissolved in a solvent) Concentrated = contains more solute Diluted = contains less solute Grams of solute per mL of solvent (g/mL)

How Concentration Affects a Solution lllustrate a concentrated and dilute solution.

Describe particles in a solution: Solubility = the ability of one substance to dissolve in another at a given temperature and pressure Example : Adding sugar to tea At colder temperatures, the sugar does not dissolve as well At warmer temperatures, the sugar dissolves quickly

Describe particles in a solution:

How to dissolve solids faster: Mix Heat Crush Stirring, shaking cause solute particles to separate , spread out more quickly in solute Solvent particles can separate solute particles and spread them out more quickly Crushed solute increases contact with solute when mixed

Suspensions Particles of mixture are more or less distributed throughout a liquid or gas Particles large enough to settle out; too large to stay in suspension; scatter, block light Can be separated by filtration Snow globe, paint, salad dressing, medicines that need to be shaken

Colloids Particles of mixture are evenly distributed but not heavy enough to settle out Can not be separated by filtration

Tyndall Effect Scattering of light as light beam passes through colloid. Particles in suspension scatter, reflect light making beam visible Seeing headlights in fog - water droplets scatter light Blue eyes – light scatters through translucent layer over iris Flour or milk in water

Explain how a colloid differs from a solution and a suspension Solution: Particles small, do not settle out, cannot be filtered, do not scatter light Suspension: Particles large, settle out of solution, can be filtered out, scatter light Colloid: Particle intermediate between solution and suspension, cannot be filtered out, scatter light

Exit Ticket 1. A mixture… A. Has substances in it that are chemically combined. B. Can always be separated using filtration. C. Contains substances that are not mixed in a definite ratio. D. All of the above 2. True or False A suspension is composed of substances that are spread evenly among each other.

Exit Ticket 1. Which of the following is not a solution? air in a scuba tank soft drink muddy water salt water 2. When solid iodine is dissolved in alcohol, which is the solute? Which is the solvent?