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