From last class

http://www.youtube.com/watch?v=nrUBPO6zZ40&safe=active

Physical and Chemical Changes

Physical Change: Changes affecting the form of a substance,

but NOT its chemical composition New properties can appear.

Properties of Matter

Colour OdourHardnessMelting/Freezing PointBoiling PointLuster

How shiny a substance is

Malleability The ability of a

substance to be beaten into thin sheets

Conductivity The ability of a

substance to allow the flow of energy or electricity

MassWeightVolumeHeightDensity

The mass of a substance divided by its volume

Physical and Chemical Changes

Chemical Change: Change in chemical composition Always causes at least one new substance to

be formed with new properties.

Indicators of Change

Heat loss or gainNew substance

formedNew properties

formedNew colour appearsColour disappearsStarting material

used upGas bubbles formedSolid (precipitate)

formsLight given off

Change in state

Change in texture

How are Chemical and Physical Changes Alike?

Both are changesNew propertiesTake timeInvolve matterNew colour (appear or disappear)Changes in texture

CHEMICAL PHYSICAL

New substanceNew molecular

formula

No new substanceNo new molecular

formula

How are Chemical and Physical Changes Different?

Videos

Factory explosionhttp://www.youtube.com/watch?v=5-nL3DaH9j4&safe=active

Woofing dog demo

Physical vs Chemical Changes Answer KeyPhysical or Chemical

Sodium Hydroxide dissolves in water.Potassium chlorate decomposes to potassium chloride and oxygen gas.Potassium metal burns when placed in water.Working a lump of clay until it softens.Water is heated and changed to steam.Grass growing in a lawn.Hydrochloric acid reacts with potassium hydroxide to produce a salt, water, and heat.Water is absorbed by a paper towel.Milk sours.

PHYSICALCHEMICALCHEMICALPHYSICALPHYSICALCHEMICALCHEMICAL

PHYSICALCHEMICAL

Evaporation.Pancakes cooking on a griddle.A tire is inflated with air.Sugar dissolves in water.Wood rotting.A pellet of sodium is sliced in two.Silver tarnishes.Food is digested in the stomach.Ice melting.

Physical vs Chemical Changes Answer Key

PHYSICALCHEMICALPHYSICALPHYSICALCHEMICALPHYSICALCHEMICALCHEMICALPHYSICAL

Physical and Chemical Changes Answer KeySituation Type of

ChangeExplanation

1. A piece of dry ice (solid carbon dioxide) is dropped into hot water. Large amounts of white vapour bubble out of the water.

Physical It’s simply a change of state. Sublimation.

2. When George’s father makes wine from crab apples, bubbles form on the surface of the yeast and fruit mixture

Chemical

You cannot revert back to the original ingredients.

3. When margarine is left in a warm place for an extended period of time, it tastes sour.

Chemical

It is changing its chemical composition. Once something sours, you cannot get it back into its original form.

4. Jane’s father opens up a new deodorant product. The room quickly smells like fresh flowers.

Physical The molecules of air are not being changed, just a new substance sprayed to make a scent.

5. During a school volleyball game, Jennifer sprains her ankle. Her coach squeezes a bag at room temperature that quickly becomes very cold.

Chemical

There is a chemical reaction happening which allows for the sensation of cold. Once the reaction wears off you cannot go back to the original state.