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Physical and Chemical Changes. Qualitative Observations- Observed using our 5 senses. Quantitative Observations- Observations using numbers (counting,

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Presentation on theme: "Physical and Chemical Changes. Qualitative Observations- Observed using our 5 senses. Quantitative Observations- Observations using numbers (counting,"— Presentation transcript:

1 Physical and Chemical Changes

2 Qualitative Observations- Observed using our 5 senses. Quantitative Observations- Observations using numbers (counting, measuring)

3 Physical changes Indicators of a Chemical change

4 Physical Change In a physical change, you do not get anything new. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

5 What is a Physical Change? A physical change is a change in which no new substance is formed, but properties may be changed.

6 What is a Chemical Change? A chemical change is a change in which a new ________ with new _________is formed. substance properties

7 Take your paper and crumple it. Do you have something new? No, it is still paper although it looks somewhat different.

8 If shape changes, then you’re observing a _______ change… physical

9 Physical changes Indicators of a Chemical changes Change of shape

10 Take your paper and rip it into 2 pieces. Do you have anything new? No, it is still paper although it looks somewhat different.

11 If you observe a change in size, then you’re observing a _______ change… physical Wet sponge Dry sponge

12 Physical changes Indicators of a Chemical changes Change of shape Change in size

13 Looking at the ice…..it has melted. Do I have anything new? No! It is still water. It has just changed its state from a solid to a liquid.

14 If you observe a change in state, then you’re observing a ________ change… physical

15 Physical changes Indicators of a Chemical changes Change of shape Change in size Change in state of matter

16 Measure out a ½ teaspoon of baking soda and put it into a cup. Was something new produced? YES! Bubbles were produced. That indicates a gas was made. The gas is a new substance. Add 3 pipettes of vinegar.

17 If you observe bubbling (not due to boiling or shaking), then a _______change is occurring… chemical

18 If you observe fizzing, then you will know that a _________ change is occurring (unless you shook the substance)… chemical

19 Physical changes Indicators of a Chemical changes Change of shape Change is size Change in state of matter Bubbles/fizzing are produced

20 Rinse out cup and refill 1/3 way with water.

21 Was the colored changed? Did you get anything new? No, you just made the colored water not as dark. You diluted it. I will pour the cup of water into the cup of colored water.

22 Physical changes Indicators of a Chemical changes Change of shape Change is size Change in state of matter Bubbles/fizzing are produced Diluting

23 Add a piece of Alka-Seltzer to your cup of water. Quickly place hand on side of cup for 3 seconds. Did you get anything new? Did you feel any temperature change?

24 Physical changes Indicators of a Chemical changes Change of shape Change is size Change in state of matter Bubbles/fizzing are produced Change in temperature Diluting

25 When we burn something….. Is a new substance produced? Yes, soot is produced or ashes.

26 If you smell burning, then you know that a change is _________ occurring… chemical

27 If you SEE burning, then a _________ change is occurring… chemical

28 Physical changes Indicators of a Chemical changes Change of shape Change is size Change in state of matter Bubbles/fizzing are produced Diluting Change in temperature Burning or cooking

29 Is melting a chemical or physical change? Physical!

30 If I add salt to water, can I separate them back into water and salt? YES! It is a mixture. So physical or chemical change?

31 Why? When a substance is not changed into a new substance, the change is only physical.

32 Physical changes Indicators of a Chemical changes Change of shape Change is size Change in state of matter Bubbles/fizzing are produced Diluting Change in temperature Burning or cooking Dissolving

33

34 Rusting? In a chemical reaction, old bonds are broken and new bonds are formed. A NEW SUBSTANCE IS FORMED. Fe and O 2 form rust (Fe 2 O 3 ).

35 Dirty silver?

36 Physical changes Indicators of a Chemical changes Change of shape Change is size Change in state of matter Bubbles/fizzing are produced Diluting Change in temperature Burning or cooking Rusting/ tarnishing Dissolving

37 If you observe that matter is__________, then a __________change is occurring… chemical decaying

38 Physical changes Indicators of a Chemical changes Change of shape Change is size Change in state of matter Bubbles/fizzing are produced Diluting Change in temperature Burning or cooking Rusting/ tarnishing Odor produced/ decay Dissolving

39 Mixing chemicals…. Glow stick What was observed? Pour 15–20 mL of copper II sulfate solution into a test tube so it is about ½ full. Add about 10–20 drops of ammonia. Add about 10–20 drops of hydrogen peroxide.

40 Physical changes Indicators of a Chemical changes Change of shape Change is size Change in state of matter Bubbles/fizzing are produced Diluting Change in temperature Burning or cooking Rusting/ tarnishing Odor produced/ decay Dissolving Change of color/ light produced

41 Physical changes Indicators of a Chemical changes Change of shape Change is size Change in state of matter Bubbles/fizzing are produced Diluting Change in temperature Burning or cooking Rusting/ tarnishing Odor produced/ decay Dissolving Change of color Precipitate formed

42 What was formed was a precipitate. Precipitate - a solid formed by mixing two or more liquids.

43 If you observe explosions because of burning, then a ________ change is occurring… chemical

44 If you observe cooking, then a _______change is occurring… chemical

45 If you observe bending (of metal, for example), then a __________change is occurring… physical Pulling metal into wires is called _________ ductile

46 If you observe reshaping (into a tube, for example), then a _______change is occurring… physical

47 If you observe pounding metal into sheets, then a _________change is occurring… physical This is called ______________. malleable

48 If you observe cutting, then a __________change is occurring… physical

49 If you observe melting, then a _______change is occurring… physical

50 If you observe rusting, then a ______change is occurring… Note: Rusting occurs when some metals react with the element Oxygen, which is in the air. For this reason, rusting is also called oxidation. chemical

51 If you observe cooling because refrigeration was added, then a _______change is occurring… physical

52 If you observe warming without the use of fire or a heater, then a ________change is occurring… chemical

53 If you observe warming with the use of fire or a heater, then a _______change is occurring… physical

54 If you observe new matter being made, then a _________change is occurring… chemical

55 Indicators of chemical reactions: Production of a gas Change in color New substance produced Change in the chemical formulas Heat is produced or absorbed Odor is produced

56 Some Examples of Chemical and Physical Changes

57 Classify each of the following as a 1) physical change or 2) chemical change. A. ____Burning a candle. B. ____Ice melting on the street. C. ____Toasting a marshmallow. D. ____Cutting a pizza. E. ____Polishing a silver bowl. Learning Check

58 Properties of Matter observations/ changes observations/ changes State of matter solid, gas, etc Density Hardness Breaking/ ripped Melting Point Taste Diluting Odor Physical Chemical Decaying Flammability Tarnishing Gas produced Burning Color change Temperature change Precipitate formed


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