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Classify the following as either a chemical change or a physical change: – Boiling – Burning On a molecular level, how would you describe the difference.

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Presentation on theme: "Classify the following as either a chemical change or a physical change: – Boiling – Burning On a molecular level, how would you describe the difference."— Presentation transcript:

1 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? Bellwork: Monday 4/23/2012 Physical Change Chemical Change Different Phase- Still same bonds; farther apart, moving faster NEW substance- Bonds broken, reformed

2 Think about it… 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

3 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 (H 2 O) – Hydrogen & oxygen combined chemically Carbon Dioxide (CO 2 ) – 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

4 Air – mixture of gases Soda pop – mixture of soda syrup, water, and CO 2 gas 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: H 2 O Salt water – mixture of salt and water Carbon monoxide – compound of Carbon and Oxygen: CO Take a Guess! Mixture or Compound?

5 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*

6 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*

7 Solubility- How well a solute will dissolve in a solvent – Insoluble- does not dissolve in water – Soluble- does dissolve in water

8 6.21- TSW IDENTIFY THE SOLUTE AND SOLVENT IN A SOLUTION. SolutionSoluteSolvent Lemonade Soda pop Ocean water Sugar (s) and Lemon Juice (l); Lemonade powder (s) Salt (s) Water (l) CO 2 – (g) carbonation/bubbles Water (l) & Syrup (l) Water (l) (s) Means it is a SOLID; (l) LIQUID; (g) GAS

9 Matter Solid, liquid, gas Pure Substance Constant Composition; Can write chemical formula, homogeneous Element One type of atom Compound Two or more different types of atoms chemically bonded Mixture Variable Composition Homogeneous solutions Heterogeneous Colloids and suspensions Matter: Pure Substances vs. Mixtures Packet 12, Page 2

10 In-Class Work: Page 2- Classify Substance vs. Mixture Type of Matter Substance- Element or Compound? Mixture- Heterogeneous or Homogeneous? Chlorine Water Soil Sugar water Oxygen Carbon dioxide Rocky road ice cream Pure air Silver Ethyl alcohol (C 2 H 5 OH) Aluminum Table salt (NaCl) Sugar Seawater Chocolate chip cookie dough Vanilla ice cream Element Compound Heterogeneous Homogeneous Element Compound Heterogeneous Homogeneous Element Compound Element Compound Heterogeneous Homogeneous

11 Page 5- Separating Mixtures Using Physical Methods: TSW SEPARATE MIXTURES USING THE FOLLOWING PHYSICAL MEANS: FILTERING, MAGNETISM, DISSOLVING, AND EVAPORATION. 1.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. 2.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.

12 3.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 4.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.

13 5.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.

14 In-Class Work: Page 4 Circle/write correct answers Whatever is not finished is homework!

15 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. 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. 1.Evaporation – how / what 2.Magnetism – how / what 3.Filtration – how / what 4.Dissolving – how / what 5.Chromatography – how / what

16 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. 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 Data Table Procedures Procedures Conclusion Questions Conclusion Questions We will be working on this lab for one day. Your mixture should be completely separated by the end of today. We will be working on this lab for one day. Your mixture should be completely separated by the end of today.

17 Separating Mixtures Lab Procedures - Page 5 Part 1 Procedure: 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: 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!!

18 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

19 Bellwork: Thursday 4/26/12 1.In the lab we did yesterday, what separation techniques worked for you and which ones did not? 2.Write the order of separation that you found to be the best. Answer the following questions on your bellwork.

20 1. Filter the large gravel from the sand, salt, iron mixture. 2. Add water to the salt and sand mixture. 3. Shake well until the salt dissolves. The sand does not dissolve. 4. Filtration: Use the filter paper and the funnel to filter into the beaker. The salt solution passes through the paper. The sand remains behind on the paper. 5. Evaporation: Put the salt solution in the evaporating basin and heat with the Bunsen burner. The water is evaporated. White salt crystals will be left behind. 6. You can dry the sand by carefully heating the wet filter paper. 7. You should now be left with separate piles of salt and sand!!


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