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Evidence of Chemical Changes

Evidence of Chemical Changes. How can you tell something has changed into something new?. Evidence we already know:. A gas is produced Evidence: you will see bubbles or hear fizzing The temperature changed What you are working with got hot or cold Endothermic = feels colder

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Evidence of Chemical Changes

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  1. Evidence of Chemical Changes How can you tell something has changed into something new?

  2. Evidence we already know: • A gas is produced • Evidence: you will see bubbles or hear fizzing • The temperature changed • What you are working with got hot or cold • Endothermic = feels colder • Exothermic = feels hotter • Color change • Think of the Statue of Liberty – it WAS copper, now it’s a green color….that’s a chemical change!

  3. More evidence! • It smells different • If something has a different odor than before, a chemical change has happened • It changes form • If you burn something, like paper • Light, heat, or sound is given off • When something explodes • If a solid forms • Science Fancy Word: solid forms = precipitate

  4. If we could see the atoms… Which part of the atom is responsible for reactivity? Hint: it’s the outermost something… Those interact with each other to form something new. The Main Point!

  5. So what is a physical change? Physical Change: you do not make a new substance Physical Change examples: • Changes states of matter (solid, liquid, gas) • Example: Water, Ice, and Steam are all the same – you have just changed the physical properties • Example: making a baseball bat out of wood – the wood has only changed shape

  6. Let’s get some practice! In the next few slides, use your ring cards to select either: • Physical Change • Chemical Change • Don’t Know Be prepared to explain why it’s the type of change it is! You can use your notes from today if you need to.

  7. Which type of change? http://whatscookingamerica.net/Foto4/BoilingWater.bmp

  8. Which type of change? http://www.google.com/imgres?q=ripping+paper&hl=en&gbv=2&tbm=isch&tbnid=thafyuekIpHt6M:&imgrefurl=http://www.bairarteditions.com/ripper/&docid=0Yf_4cf2jAxknM&w=576&h=317&ei=pblyTvWRM5TJsQL46pDaCQ&zoom=1&iact=hc&vpx=675&vpy=190&dur=889&hovh=166&hovw=303&tx=211&ty=69&page=1&tbnh=94&tbnw=171&start=0&ndsp=15&ved=1t:429,r:4,s:0&biw=1024&bih=630

  9. Which type of change? Digesting Food http://www.google.com/imgres?q=digesting+food&hl=en&gbv=2&tbm=isch&tbnid=3w1uFRwVZsXKyM:&imgrefurl=http://byhealth.com/digestive-system&docid=EsLSOzq6M__IvM&w=699&h=837&ei=-7lyTtvvCO7LsQK-0bCZCw&zoom=1&biw=1024&bih=630&iact=rc&dur=265&page=1&tbnh=109&tbnw=91&start=0&ndsp=17&ved=1t:429,r:4,s:0&tx=69&ty=39

  10. Which type of change? Flammability http://www.google.com/imgres?q=flammability&hl=en&gbv=2&tbm=isch&tbnid=REMWMZsxrWRlJM:&imgrefurl=http://www.sgs-cqe.de/en/flammability-test-for-plastic-materials-/-components.html&docid=ZGVnk1mVtYju6M&w=275&h=199&ei=srpyTqWoBcKAsgLPspi_CQ&zoom=1&iact=hc&vpx=468&vpy=131&dur=1856&hovh=159&hovw=220&tx=133&ty=102&page=1&tbnh=123&tbnw=162&start=0&ndsp=15&ved=1t:429,r:7,s:0&biw=1024&bih=630

  11. Which type of change? http://custom.buyitsellit.com/29169/images/staedlter/pencils/158_sharpening.jpg

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