Bellringer – Week 3

1. Describe the pencil or pen you are using. Be very specific.

If all of the pencils and pens in the classroom were mixed together would we be able to identify yours from your description?

Properties of matter can be divided into 2 categories: Physical Physical

PropertiesProperties

Properties that can be observed or measured without changing the identity of the matter

Chemical Chemical PropertiesProperties

Properties that describe a substances ability to change into a new substance.

Physical Properties

Basic Properties

ColorOdorSize (Mass,Volume)ShapeTexture

Complex Properties

Thermal ConductivityState of MatterMalleabilityDuctilitySolubilityDensity

Complex Properties

Ductility-ability to bend without breaking

Malleability-capable of being shaped

Solubility-capability of being dissolved

Density

Density is the amount of matter in a given space and the formula is:

D = mass/volume It’s SI units are:

g/ml, g/cm3, kg/m3 or kg/L (but any mass unit/volume unit is

correct)

Density

Density is a useful property for identifying an object because:

1. The density of a particular object is always the same at a given pressure & temperature.

2. The density of one substance is usually different from that of any other substance

3. Density does not change with the size of the object

Please Do Now

Solve the following density problems: metal A block of aluminum occupies a volume of

15.0 ml and weighs 40.5 g. What is its density?

Mercury metal is poured into a graduated cylinder that holds exactly 22.5 ml. The mercury used to fill the cylinder weighs 306.0 g. From this information, calculate the density of mercury.

The following liquids were spilled into a tank A green liquid that has a volume of

48 L and a mass of 36 kg A blue liquid that has a volume of

144 L and a mass of 129.6 kg A red liquid that has a volume of 96 L

and a mass of 115.2 kg A black liquid that has a volume of

120 L and a mass of 96 kg

Density work cont’d

1. Calculate the density of each liquid:2. Determine the order in which the

liquids have settled in the tank: First (bottom)

SecondThird

Fourth (top) 3. Use crayons to sketch the layers in

the tank

Chemical Properties

Chemical properties are not as easy to observe as physical properties

Two of the main chemical properties are:Flammability – the ability to burn

(aka: Combustible)Reactivity – when 2 substances combine,

something happens!(explode, change color, make a noise or

create an odor, bubble, fizz)

Chemical & Physical Properties of a Car

Positive PropertiesIron is strong,

malleability, high melting point

Iron is NON reactive with oil and

gasolinePaint does not react

with oxygen

Negative Properties

Iron is reactive with water and oxygen – It causes rust!!!

Physical & Chemical Changes

Physical Changes

A physical changephysical change is a change that affects one or more of its physical properties.

The substance involved remains the same even though it may change shape or form

Physical changes can usually be undones

All changes in phase are physical changes

Physical Change

vaporization

condensation< Melting

Freezing >

sublimation

Examples of Physical Changes Freezing water Cutting your hair Bending a paper clip Crushing up a piece of chalk Dissolving salt in water

Chemical Changes

A chemical changechemical change occurs when one or more substances are changed into entirely new substances.

Most chemical changes cannot be undone by physical means….but some can be undone by going through additional chemical changes.

Evidence of Chemical Changes Clues that a chemical change has

occurred include: Change in color Fizzing or foaming Generation of heat, sound, light or odor A solid material called a precipitate is

formed Difficult to reverse

Precipitate

Review: Physical or Chemical Change?

Physical Chemical

Change in state Substance remains

the same Reversible Did it dissolve?

New substance is formed

Change in color Heat or light given off Bubbles are formed Precipitate is formed Difficult to undo

Bellringer

How could you calculate the density of water?

Please explain the procedures and calculations you would use.

Bellringer

What is volume?

What are 3 ways to measure it?