chapter 2: properties of matter 2.3 properties are used to identify substance have learned: -matter...
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Chapter 2: Properties of Matter2.3 Properties are used to identify substance
Have learned:-Matter can change from one state to another-changes in state require energy changes
To learn:To learn:-how properties can -how properties can help you identify help you identify substancessubstances-how properties of -how properties of substances can be substances can be used to separate used to separate substancessubstances
Substances have characteristic properties
Identify unknown substance - scientificallyIdentify unknown substance - scientificallyObserve and measureObserve and measure color, odor, texture, color, odor, texture, density, boiling point, freezing point...density, boiling point, freezing point...
Taste????!Taste????!Think glue vs. milk, paper textures, coins,Think glue vs. milk, paper textures, coins,
Colorless liquids???Colorless liquids???
Could compare the properties of the Could compare the properties of the unknown and compare it to properties of a unknown and compare it to properties of a known substanceknown substance
http://www.mysterycargo.info/sections/index.php/identifyingSubstances/keyingLiquids/
Click on “experiments” then “clue cards”
From: http://www.mysterycargo.info/identifyingSubstances.html “keying liquids”
Properties used for identifying substances -
DensityMass and volume (Density = mass/volume)
Two objects can have the same mass…but be different substance
Measure volume: determine density Density of one substance is the same no matter what the sample size
Many substance densities are knownCan compare the density of an unknown substance to a list of known substances and their densities
…though some substances do have the same density…
Properties used for identifying substances –
Heating PropertiesSubstances respond to heating in different Substances respond to heating in different waysways
Warm up or cool down time variesWarm up or cool down time variesConduct heat well – aluminum and ironConduct heat well – aluminum and iron
Household insulation – poor conductor/good Household insulation – poor conductor/good insulatorinsulator
Can measure the rate at which a substance Can measure the rate at which a substance conducts heat and compare that rate with conducts heat and compare that rate with the heat conduction rates of other the heat conduction rates of other substancessubstances
Properties used for identifying substances – Solubility &
ElectricSolubility: Measure of how much of a substance dissolves in a given volume of liquid
Ex: sugar and dirtCan test the solubility of an unknown substances
Electric” some substances conduct electricity better than others
They allow electric charges to move through them easily
Ex: Copper wire is a good conductor of electricity – rubber is not!
Can test the electrical conductivity of an unknown substance
Properties used for identifying substances –
MagneticSome substances are attracted to magnets, but others are not
Ex: paper clip vs plastic button
Magnetic: iron, cobalt, and nickel
Not magnetic: copper, aluminum, zinc
Mixtures can be separated by using the properties of the
substances in themEx: bag of cans for recycling
How to separate aluminum from cans with steel?
Different magnetic properties
Ex: a filter can be used to separate solids from liquids, or different sizes
Ex: tea bag allows water to passEx: coin separationEx: sand, gravel, pepper filter pass
Evaporation: evaporate water from an open dish to see what substance remains
Mixtures can be separated by using the properties of the substances in them
Water Treatment plant - separates substances mixed in with water
Add chemicals to cause large particles to stick to each other – they settle to the bottom
Water is run through molecular filters – removing smaller particles
Chlorine treatment to disinfect the water
Video hazmat
Element – specific emission spectrum
colors of the solar continuum
solar spectrum with its absorption lines
Hydrogen
Oxygen
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