Chemical PropertiesSection 17.3
Realplayer videos\JCE Software Chemistry Comes Alive!.mov
Demo - Candle• What physical changes can be made to
each item?– Candle– Match– Stick
• Light the match and put it near the side of the candle. Is the melting wax a physical or a chemical change?
• Light the candle. As the wax and the wick burn, is it a physical or a chemical change?
Chemical Properties of Matter• Chemical properties describe a substance’s ability
to change into new matter with new properties.
Realplayer videos\Video pedia World - Elements Of Chemistry Chemical Reactions2.flv
– Flammability: describes whether substances will react in the presence of oxygen and burn when exposed to a flame
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Chemical Properties– Reactivity: describes the ability of two
or more substances to combine to form one or more new substances.• Rusting – reactivity with oxygen• Explosive reaction of elemental
sodium with chlorine to form table salt
Realplayer videos\Bill Nye The Science Guy on Chemical Reactions (Full Clip) - Bing Videos.flvRealplayer videos\Reaction of Sodium Chlorine (with subtitles).flv
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Chemical Property Applications• Galvanized steel is steel coated with
zinc to prevent rusting (buckets, nails).
• Steel plated with tin was once used in food cans and containers. Today, aluminum cans have replaced most steel cans.
Interesting Facts• Before the early 1960s, there was a
group of gases (named noble gases) that were thought to be unreactive. However, in 1962, Dr. Neil Bartlett of Univ. of Brit. Columbia formed a new compound by combining platinum, fluorine, and the noble gas xenon.
• In 2002, chemists created new compounds by bonding uranium with argon, krypton and xenon (all noble gases).
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Interesting Facts• Chromium has been used as
a coating on car bumpers because it is nonreactive with oxygen (so the bumper is protected from rusting).• Rustproofing involves treating the car’s
underside and panels with sealants, which penetrate the seams, cracks, and holes to keep out air and moisture – which would increase the rate of rusting.
Substance Identification• Characteristic properties are used to
identify and classify substances. They can include both physical and chemical properties. Examples: density, solubility, flammability, reactivity
• These properties do not depend upon the size of the sample (so mass, weight and volume would not be characteristic properties).
Substance Identification• Example: How can you tell the
difference between baking soda and baking powder if they are out of their container?
• Reactivity with vinegar:– Baking soda reacts– Baking powder does not
Realplayer videos\SloMo - Baking soda + vinegar reaction @ 420 fps - Bing Videos.flv
Chemical Changes• Chemical changes are
the processes by which one or more substances are changed into new substances.
Indicators of Chemical Change• Change in color or scentRealplayer videos\Chemical Changes color change.mov• Production of a gas – fizzing,
foaming, effervescence.Realplayer videos\Chemical Changes gas production.mov
Indicators of Chemical Change• Production of a solid (precipitate)Realplayer videos\Precipitate formation Chemistry Comes Alive!.mov
• Production of heat• Production of light or soundRealplayer videos\Heat released in chemical reactions Chemistry Comes Alive!.mov
• What indications of chemical change do you see in the next video?
Realplayer videos\Indicators of chemical change.flv
Chemical Changes• Matter’s identity is changed in a chemical
reaction. • Reversing a chemical reaction (getting
back what you started with) is not always possible. If it is possible, it requires more chemical changes to take place.• Could you reverse the explosion of
fireworks?
Physical Changes• Since physical changes don’t change the
composition of a substance, they are frequently easily reversible.
• Example: Heating an ice cube to make it melt e cool the resulting liquid to make it freeze
• Dissolving a solid in a liquid e making the substance recrystallize from the solution
Realplayer videos\Crystallization of supersaturated sodium thiosulfate - Bing Videos2.flv
References:• http://www2.chemistry.msu.edu/portraits/PortraitsHH_Detail.asp?HH_LName=BartlettN• http://www.kenyacarbazaar.com/blog/?p=899• http://carondelet.net/Aspring08/Project2/Caitlin/New%20York%20City.htm• http://www.artmetal.com/images/sculpture_gallery/josh/2007/07/rusted_sculptures_update_0• http://www.manufactum.com/Artikel/99272/2GalvanizedSteelPlantTub.html• http://besbryant.sharpschool.com/cms/One.aspx?portalId=839802&pageId=2630106• http://mbt6644.k12.sd.us/frontpage1/project1/inthelab1/pictures.htm• http://miamirealestatecafe.com/2009/12/28/cleaning-tips-for-your-miami-home-using-everyday-items• http://www.bbc.co.uk/food/baking_powder• http://www.etftrends.com/2010/07/price-impact-aluminum-etf/• http://www.icollector.com/Lot-Of-7-Tin-Cans-Texaco-Capella-Oil-Tin-Can-Transmi_i8458786• http://qwickstep.com/search/chemical-changes-examples.html• http://www.chemistryland.com/CHM130W/04-Properties/PropertiesBook/ChangesAssignment.htm• http://www.queenmaryschool.net/ScienceFair/?tag=/chemical-change• http://picsdigger.com/keyword/chemical%20changes/• http://jchemed.chem.wisc.edu/JCESoft/CCA/pirelli/pages/cca1NaIHgCl2.html• http://www.treklens.com/gallery/North_America/Canada/photo154072.htm• http://micro.magnet.fsu.edu/moviegallery/chemicalcrystals.html