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?