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Changes of State

Changes of State. 8 th Grade Science Mr. Monson’s Class. Change of State. Change of State is the change of a substance from one state to another. Four basic changes of states. Melting Freezing Evaporation Condensation. 5 th change of state.

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Changes of State

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  1. Changes of State 8th Grade Science Mr. Monson’s Class

  2. Change of State • Change of State is the change of a substance from one state to another

  3. Four basic changes of states • Melting • Freezing • Evaporation • Condensation

  4. 5th change of state • Sublimation – the process in which a solid changes directly into a gas • Example Dry Ice (CO2)!

  5. Energy and Change of States • Changes of state is the change of a substance from one physical form to another • All Change of states are physical changes Why is a change of state a physical change?

  6. Energy & Change of States • Particles of a substance move differently depending on the state of a substance • Particles have different amounts of energy in different states Solid least energy Liquid more energy Gas most energy

  7. Change from one State to Another . . . • To change from one state to another you must add energy or remove energy

  8. Change of State Triangle

  9. Melting: Solid into Liquid • Add energy to a solid can cause melting • Melting is the change of state from a solid to a liquid There are two changes taking place in this picture can you identify them?

  10. Melting: Solid into Liquid . . . • Melting Point -the temperature a solid changes to a liquid • to melt particles must overcome some of the attraction to each other

  11. Melting Point . . . • Melting is an endothermicreaction (energy is gained) • As energy is gained the temperature rises

  12. Melting Point . . . Endothermic • Example: gallium • Is a metal • Melting point 30oC • Human temperature 37oC • Why would gallium make a bad ring? Change

  13. Melting Point . . . • Salt’s (NaCl) melting point is 801oC • Salt will not melt in your hand Melting Salt in Vats in China

  14. Freezing: Liquid to Solid • Freezing: change of state from liquid to solid • Freezing is the reverse process of melting

  15. Freezing Point • Because freezing is the reverse process of melting . . . • Freezing and melting occur at the same temperature Water & ice 0oC

  16. Freezing/Melting Point • Add more energy – melting will continue • Remove the energy and freezing will increase

  17. Removing Energy . . . • Exothermic ChangeEnergy is removed from a substance to freeze it

  18. Boiling and Evaporation • Evaporation is the change of substance from a liquid to a gas • Boiling is the change of a substance from liquid to vapor • Occurs when pressure inside Bubbles equals pressure Outside bubbles.

  19. Effects of Pressure at Boiling Point • Boiling point is affected by where you are at in comparison to sea level. • The lower or closer to sea level the higher the boiling temperature

  20. The higher up from sea level the lower the boiling temperature

  21. Comparing Altitude & Boiling Point

  22. Condensation • Condensation is Gas going to a liquid • Condensation point is temperature gas turns into a liquid • Exothermic reaction because energy is removed (the temperature goes down) • Example: Dew

  23. Sublimation • Solid going to a gas • Endothermic because there is an increase in energy (temperature) • Example Dry Ice

  24. Both the temperature and state are affected by the energy/ movement of particles Temperature of a substance is related to the speed of the substance particles Change of Temperature v. Change of State

  25. Note: the change of temperature does not take place until the state has completely changed 100 oC

  26. Remember. . . . • Change of state has concurrent changes

  27. References • http://www.ewart.org.uk/science/structures/states.jpg 10/12/09 • http://www.all-water.org/H2O_Images/800px-DryIceSublimation.JPG 10/12/09 • https://tas-ms-8sci-go-p7.wikispaces.com/file/view/state.gif/32513769 10/12/09 • http://misterguch.brinkster.net/energydiagram3.gif 10/12/09 • http://202.114.88.54/g/web18/wangluo/webelements/webelements/properties/media/tables/intensity/melting-point.gif 10/12/09 • http://www.periodictable.ru/031Ga/slides/Ga1.jpg 10/12/09 • http://media.rd.com/rd/images/rdc/mag0805/cutting-back-on-salt-01-af.jpg 10/12/09 • http://www.cringel.com/files/images/adia_2007_03_15_DSC_5503_salt_farm_worker_vietnam_ninh_hoa_cringel.com.jpg 10/12/09 • http://www.cbc.ca/gfx/images/news/photos/2009/01/16/full-watermain090116.jpg 10/12/09 • http://www.andybrain.com/sciencelab/wp-content/uploads/2008/04/ice-water-volume.jpg 10/12/09 • http://away.com/gifs/states/wy/yel_icef.jpg 10/27/09 • http://aaronandsarah.files.wordpress.com/2008/09/canyon-waterfall-2.jpg 10/27/09 • http://www.gsaclt.com/customers/106082309312252/images/delta_therm_snow_picture.jpg 10/27/09 • http://www.fakefoodonline.com/i/Ice%20Cream/product_image_13.jpg 10/27/09 • http://www.clipartguide.com/_thumbs/0060-0502-2515-5358.jpg 10/27/09 • http://www.its.caltech.edu/~atomic/snowcrystals/icespikes/icespike.jpg 10/27/09 • http://blog.hotelclub.com/wp-content/uploads/2008/04/chile_hot_springs.jpg 10/27/09 • http://www.clickandlearn.org/images/water_cycle.gif 10/27/09 • http://www.epicurious.com/images/articlesguides/howtocook/primers/highalt_illustration1.gif 10/27/09 • http://farm1.static.flickr.com/61/189332042_a25deba877.jpg 10/28/09 • http://www.quantumtheatre.co.uk/BigDrip%20ks1_files/image008.jpg 10/28/09 • http://rachellekoch.com/blog/wp-content/uploads/2009/07/Bumpass-Hell-Steam.jpg 10/28/09

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