Presentation on theme: "9/29/30 Tape in Your Warm up and Complete Justify Your Answer Choice: I -STARTER: Warm up about elements. III- APPLICATION IV –CONNECTIONS: 10/18/11 Justify."— Presentation transcript:
9/29/30 Tape in Your Warm up and Complete Justify Your Answer Choice: I -STARTER: Warm up about elements. III- APPLICATION IV –CONNECTIONS: 10/18/11 Justify Your Answer Choice: II- PRACTICE: Prelab Notes III- APPLICATION IV –CONNECTIONS: V -EXIT: 3-5 Summary Sentences
I: Starter Turn to your next blank page and write the date at the top Tape your warm up directly underneath and complete! Justify you r answer out to the side of your warm up.
II: Practice Water or Not??? Please take notes in this section to prepare for the lab we will be completing in today’s application section. ?
Let’s do a quick review…
What is a element? Pure substance that can not be chemically broken down What is a compound? 2 or more atoms chemically combined that cannot be physically pulled apart Are Elements found on the Periodic Table? Yes Are Compounds found on the Periodic Table? No.
What is a physical change? Rearranges molecules but doesn’t affect their internal structures. Some examples: 1)Whipping egg whites – air is forced into the fluid, but no new substance is produced! 2)Sugar dissolving in water – sugar molecules are spread within the water, but the individual sugar molecules are unchanged 3)Boiling water –water molecules are forced away from each other when the liquid changes to vapor, but molecules are still H2O 4)Dicing potatoes – cutting usually separates molecules without changing them.
What is a chemical change? Any change that results in the formation of new chemical substances. At the molecular level, chemical change involves the making or breaking of bonds between atoms. These changes are chemical: 1)Iron rusting – Iron oxide forms through the reaction of iron and oxygen in the presence of water or air moisture. 2)Gasoline burning – when gasoline is burned in car engines, water vapor and carbon dioxide form. 3)Bread rising – Yeast changes carbohydrates into carbon dioxide gas. 4)Milk souring – When bacteria use the lactose sugars in milk they change the sugar and sour-tasting lactic acid is produced.
SIGNS OF CHEMICAL CHANGE (How can you tell?) – Gas Formation – a gas is formed & released as the reaction is completing (NOT the same as boiling) – Solid formation (precipitate) – a solid “rains down” to the bottom of the container, may be suspended in a cloudy solution – Temperature Change – It takes energy to break chemical bonds. Energy is released (heat) OR energy is absorbed (cold). – Color Change – Not the same as mixing colors. – Light is given off – Change in smell (or taste)
Last week we looked at 2 liquids that appeared to be identical: H2OH2OH2O2H2O2 water Hydrogen peroxide
Water It’s chemical formula is H 2 O It is drinkable. May be used to clean wounds. – What happens when water is put on a wound? What do we know about these 2 compounds so far?
Hydrogen Peroxide It’s chemical formula is H 2 O 2 In its pure form could be fatal swallowed!! Antiseptic that is an effective way to clean wounds. – What happens when Hydrogen Peroxide is put on a cut? It causes bubbles – What are these bubbles a sign of? » A Chemical Reaction
Details of how Hydrogen Peroxide works Hydrogen Peroxide is 3% H 2 O 2 and 97% water Blood cells contain an enzyme called catalase – When you get a cut or scrape both blood and damaged cells release catalase
When H 2 O 2 comes into contact with catalase a chemical reaction occurs 2H 2 O 2 + catalase 2 H 2 O + O 2 – The reaction causes the peroxide to turn into pure oxygen Bubbles are the release of the extra oxygen gas Details of how Hydrogen Peroxide works
III: Application For today’s application we are going to be working in groups to figure out Water or Not??? Your group will receive 2 cups of clear liquid We CAN NOT test on humans in this class! – No drinking the liquids – No putting the liquids on any body parts
So how can we test to see if the liquids are H 2 O or H 2 O 2 ??? With a potato
III: Application Draw the set up that has been passed out to each group showing both cups of liquid Gently place one slice of potato into cup A – Observe and draw/label reaction Repeat for cup B You should label as appropriate in each picture: – Potato – Hydrogen Peroxide – Water – Oxygen Bubbles
Clean Up When done carefully remove potato slice with plastic spoon, place in paper towel, and dispose in trash. Return cups with remaining liquid and supplies as provided to you at beginning of experiment.
IV: Connections Describe why it is important to clean cuts with hydrogen peroxide a couple of times a day for several days after injury? V: Exit Summarize what you have learned during this lesson. (3-4 sentences, please!)