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Bellwork: Monday 4/23/2012 • Classify the following as either a chemical change or a physical change: • Boiling • Burning • On a molecular level, how would you describe the difference between boiling something, and burning something? Different Phase- Still same bonds; farther apart, moving faster Physical Change Chemical Change NEW substance- Bonds broken, reformed
A garden salad is made up of lettuce, tomatoes, cucumbers, ham, egg, bacon bits, and croutons. Compare this to dissolving sugar into un-sweet tea. Hint: think about each of them as different things being mixed together—what is the end result?? The salad is not a uniform mixture (one bite is different from the next) – the salad is a heterogeneous mixture The tea is a uniform mixture – once dissolved, the sugar is spread out evenly in the tea so one sip tastes like another – the tea is a homogeneous mixture Think about it…
Packet 12, Page 1- Mixtures & Solutions • Compound- two or more substances chemically combined • Only separated by chemical means/reactions • Examples of compounds: • Salt (NaCl) – Sodium & chlorine combined chemically • Water (H2O) – Hydrogen & oxygen combined chemically • Carbon Dioxide (CO2) – Carbon & oxygen combined chemically • Mixture- two or more substances mixed together; NOT chemically combined • Separated by physical means • Examples of mixtures: • Bowl of cereal – mixture of cereal and milk • Trail mix- mixture of various nuts, fruit, candy
Take a Guess! Mixture or Compound? • Air – mixture of gases • Soda pop – mixture of soda syrup, water, and CO2gas • Fog – mixture of water and air • Table salt – compound of Sodium and Chlorine: NaCl • Kool-Aid – mixture of water, sugar, and flavor crystals • Water – compound of Hydrogen and Oxygen: H2O • Salt water – mixture of salt and water • Carbon monoxide – compound of Carbon and Oxygen: CO
6.19- TSW USE EVIDENCE TO COMPARE AND CONTRAST HOMOGENEOUS AND HETEROGENEOUS MIXTURES. • Heterogeneous mixture- a mixture in which the properties are not uniform (ex. beef stew, garden salad) • “Uniform” means the same throughout • Suspension- *solid is not dissolved*Very fine particles of solid mixed with a liquid; often looks cloudy; eventually solid settles to the bottom • Sediment- *solid is not dissolved and settles to the bottom*
Homogeneous mixture- a mixture in which the properties are uniform (ex. sweetened tea) • Solution- *solid is dissolved*mixture in which one substance is dissolved in another; has two parts: • Solute- is dissolved (s, l, g) • Solvent- does the dissolving (s, l, g—usually liquid) • *The solute is present in a smaller amount than the solvent*
Solubility- How well a solute will dissolve in a solvent • Insoluble- does not dissolve in water • Soluble-does dissolve in water
6.21- TSW IDENTIFY THE SOLUTE AND SOLVENT IN A SOLUTION. Sugar (s) and Lemon Juice (l); Lemonade powder (s) Water (l) Water (l) & Syrup (l) CO2 – (g) carbonation/bubbles Water (l) Salt (s) (s) Means it is a SOLID; (l) LIQUID; (g) GAS
In-Class Work: Page 2- Classify Substance vs. Mixture Element Compound • Heterogeneous Homogeneous Element Compound • Heterogeneous Homogeneous Element Compound Element Compound Compound Homogeneous • Heterogeneous Homogeneous
Page 5- Separating Mixtures Using Physical Methods: 6.20- TSW SEPARATE MIXTURES USING THE FOLLOWING PHYSICAL MEANS: FILTERING, MAGNETISM, DISSOLVING, AND EVAPORATION. • Filtration- separates a solid (or suspension) from a liquid • Example: separate dirt from some salty water • How it works: The liquid (and anything dissolved in the liquid) passes through holes in the filter paper. The solid particles are too big and get stuck. • Magnetism- separates objects with magnetic properties, from non-magnetic objects • Example: separate iron from sand • How it works: The magnet sticks to the iron, not the sand.
Dissolving- causes solid matter to pass into a liquid solution; “disappears” • Example: the dissolving of salt in water • How it works: Soluble solids will dissolve, while insoluble solids will not • Evaporation- separates a dissolved SOLUTE from a SOLUTION • Example: obtain some pure salt from salty water • How it works: When salty water is warmed the water evaporates leaving behind crystals of salt.
Paper Chromatography- separates the different colors in dyes • Example: separate the different colored dyes in ink pens • How it works: Place a dot of the dye to separate, on chromatography paper, and then dip it into a solvent. As the solvent soaks up through the paper it carries the dye with it. The more soluble dyes move further up than the less soluble ones, hence separating from each other.
In-Class Work: Page 4 • Circle/write correct answers • Whatever is not finished is homework!
Bellwork: Tuesday 4/24/2012 • Choose one of the five separation techniques we have studied so far and describe how they can be used to separate a mixture, and what they separate. • Evaporation – how / what • Magnetism – how / what • Filtration – how / what • Dissolving – how / what • Chromatography – how / what
Separating Mixtures Lab- Page 5 • Objective: Students will design, conduct, and justify an experimental design in which they combine sand, iron filings, gravel, and salt, and then use physical means to separate the mixture. • Data Table • Procedures • Conclusion Questions • We will be working on this lab for one day. Your mixture should be completely separated by the end of today.
Separating Mixtures Lab Procedures - Page 5 • Part 1 Procedure: • Measure and record the “original mass” of the sand, iron fillings, gravel, and salt in the data table on pg. 6. • Combine the sand, iron fillings, gravel, and salt in a beaker; stir until the substances are a complete jumble! • Challenge: • Along with your partners, you must now find a way to separate the jumble that you have created in your beaker back into the original substances: sand, iron fillings, gravel, and salt. • You may only use the tools you have been given! • Use Part 2 Procedure on pg. 6 to complete the challenge! • We don’t have a hot plate or blow dryer so MEASURE THE MASS OF WATER IF YOU USE IT!!
Separating Mixtures Review • Filtration- separate a solid or suspension from a liquid • separating SAND from water • Magnetism- separate magnetic objects from non-magnetic objects • separating iron from salt • Dissolving- causes solid matter to pass into a liquid solution; “disappears” • Evaporation- used to obtain the solute from a solution • obtaining SALT from salty water • Chromatography- used to separate out one color from a mixture of colors • separating out the colors in black ink
Bellwork: Thursday 4/26/12 • In the lab we did yesterday, what separation techniques worked for you and which ones did not? • Write the order of separation that you found to be the best. Answer the following questions on your bellwork.