SCIENCE REVIEW

TEST READINESS

PHYSICAL PROPERTIES AND CHANGES

COMMON PROPERTIES OF MATTER

All matter has

- Mass

- Weight

- Volume (takes up space)

- Shape

PROPERTIES OF MATTER

Brittleness - the property of matter that is how easily the substance breaks or shatters when force is applied to it.

Elasticity - the ability of a substance to be stretched and then to return to its original shape.

Hardness - property of matter that determines how easily the substance can be scratched.

PROPERTIES OF METALS

Ductility - property of a metal in which it can be stretched without breaking.

Malleability - the property of a metal that allows it to be hammered, rolled, pressed or forged.

Conductivity – property of a metal that allows it to conduct electricity

Magnetism – the property of a metal in which it is attracted to a magnet

How do I study for a Science quiz?

Types of Science Questions

KNOWLEDGE What is the freezing point of water?

COMPREHENSION Explain the difference between physical and chemical change?

ANALYSIS Which is a physical change and why?Sugar dissolved in waterBurning paper turning into ash

SYNTHESIS In cold countries salt is strewn on icy roads. Explain the scientific reasoning behind this.

Key words: Physical Change

Boiling point

Melting point

Sublimation

Deposition

Solidification or Freezing

Evaporation

Filtration (separation technique)

Solution = Solute + Solvent

What is a physical change?

Give a real life example of a physical change?

Requires energy from environment

Cooling Process

Releases energy to environment

Warming Process

Changes in States of Matter

DepositionEvaporationSolidification/FreezingMeltingSublimation Condensation

Tem

pera

ture

(deg

rees

Celsiu

s)

Time (minutes)

0

100

Time- Temperature Graph for Water

Why is the slope of the graph flat (no temperature change) at 0 degrees?

Why is the slope of the graph flat (no temperature change) at 100 degrees even though the stove is still on?

What is true for the ice-water mixture when the temperature began to rise?

Why did temperature increase at a constant rate?

When will the temperature of the water rise above 100 degrees Celsius?

Tem

pera

ture

(deg

rees

Celsiu

s)

Time (minutes)

0

100

Time- Temperature Graph for Water

As the temp approaches melting point temperature, the KE of the water molecules increases loosening the bonds between water molecules.

As the ice begins to melt, additional heat energy does not raise the temperature of the water, but loosens the bonds changing ice to water. i.e. phase change – melting.

Once the water is in a liquid phase, increasing the amount of heat input raises the temp of the liquid water.

As the temp approaches boiling point, the KE of the molecules is sufficient to allow the separation of molecules into the gas phase.

As the liquid begins to boil. Additional input of heat energy does not raise the temperature of the water, rather it is used to break water bonds. i.e. phase change.

Once the water is in the gas phase, additional heat input raises the temperature of the water vapor Note: greater energy is needed to vaporize water than to melt it. WHY?

Phase Change- _________energy from stove = energy required for phase

change

____ temperature change

Phase Change- ___________energy from stove = energy required for phase

change

______ temperature change

Energy from stove causes

increased ____E and increased ___________

Energy from stove causes

increased ___E and increased _____________

______ states of Matter

______ states of Matter

_____ states of Matter

Phase Change- Meltingenergy from stove = energy required for phase

change

No temperature change

Phase Change- Vaporizationenergy from stove = energy required for phase

change

No temperature change

Energy from stove causes

increased KE and increased Temperature

Energy from stove causes

increased KE and increased Temperature

Two states of Matter

Two states of Matter

One state of Matter

The Water Profile

Boiling point

temperature at which a liquid changes to a gas

Melting point

the temperature at which a substance changes from a solid to a liquid.

Solidification (freezing)

changing of a liquid to a solid

Salt on snow-covered roads?

If you live in an area with a cold and icy winter, you have probably experienced salt on sidewalks and roads, used to melt the ice and snow and keep it from refreezing.

Salt is also used to make homemade ice cream.

In both cases, the salt works by lowering the melting or freezing point of water. The effect is termed freezing point depression

So, when you add a salt to ice with a little bit of water, the salt lowers the freezing point of the water, keeping it from re-freezing as easily and helping to melt the rest of the ice.

Sublimation

the changing of a solid directly to a gas

Example

Dry ice is solid carbon dioxide. At room temperature and pressure, it sublimates into carbon dioxide vapor.

Deposition

this is a phase change from a gas directly to a solid

Iodine test: http://www.youtube.com/watch?v=4fAOI6BeMZY

Dry Ice The Iodine

Test

Evaporation

changing of a liquid to a vapor at any temperature below its boiling point.

Alcohol Water Oil

NATURE OF THE SUBSTANCE

Why does alcohol evaporate faster?

Both alcohol and water have hydrogen molecules that bond. However, the bonds in alcohol molecules are weaker which allows for alcohol to evaporate faster.

2. Copy and complete the following sentences using the words below:

Solution solvent solutesaliva dissolves exposed saliva

The candy dissolves in the ……………………..in your mouth to form a liquid ………………………….. Solutions contain two parts, a ………………….. and a ……………………………….

The solvent is …………………….. and the solute is the candy. The solute……………………….. by spreading out evenly throughout the solvent. The candy can quickly dissolve when it is ……………… to chewing and stirred by moving it around with the tongue.

Pressure Cooker Visualizer

Ms Pommeroy cooks rice in a pressure cooker. Why?

A pressure cooker is a sealed pot.

Steam trapped inside the pot under pressure allows the temperature to rise beyond what it could reach normally in a traditional uncovered pot.

As the pressure inside the cooker increases, the boiling point of the water inside increases as well. This causes the food to cook at a higher temperature, which cooks it faster.

CHEMICAL CHANGE PHYSICAL CHANGE

In a chemical change where there is a chemical reaction, a new substance is formed and energy is either given off or absorbed.

A physical change in a substance doesn't change what the substance is.

If a piece of paper is burned, it is broken up into different substances that are not paper.

For example, if a piece of paper is cut up into small pieces it still is paper. This would be a physical change in the shape and size of the paper.

Chemical changes cannot be reversed with the substance changed back without extraordinary means, if at all.

Physical changes can be reversed.

If one made a recipe for a cake with flour, water, sugar and other ingredients and baked them together, it would take extraordinary means to separate the various ingredients out to their original form.

If one decided to mix sugar/salt into water to make sugar/salty water, this would be a physical change as the water could be left out to evaporate and the sugar/salt crystals would remain. Note: remember salt is sodium chloride (NaCl)

GOOD LUCK!

Photo Credit: http://www.flickr.com/photos/kotomi-jewelry/4229169566/