1. Physical versus Chemical Properties
Unit II - Part 1
The study of matter

2. Reviewing MATTER Matter: anything that has mass and takes up space
Mass – the amount of matter in something
Volume – the amount of space something occupies
Which of the following is matter?
A car?
A box?
You?

3. What is a property?
Property: a characteristic of a substance that can be observed

4. Physical Property
Physical property: a property that can be observed without changing the identity of the substance.
Examples:
luster
malleability: the ability to be hammered into a thin sheet
ductility: the ability to be stretched into a wire
melting point
boiling point
density
solubility
specific heat

5. Special Physical Properties
Melting point: the temperature at which a substance changes from a solid to a liquid at a given pressure
water = 0oC
Boiling point: the temperature at which a substance changes from a liquid to a gas at a given pressure
water = 100oC

6. Chemical Properties
Chemical property: a property that can only be observed by changing the identity of the substance
Examples:
flammability
ability to rust
reactivity with vinegar

7. Density Density is the amount of mass per unit of volume.
Density can be used to identify a substance.
The density of water is 1.0g/mL

8. Density Formula
Remember: When calculating density, your answer must have two units!
Ex: g/ml or lbs/gallon

9. Density Calculations Calculations:
D = m/V = g/mL = g/cm3
Ex: A cube has a mass of 2.8 g and occupies a volume of 3.67 ml. Would this object float or sink in water?
Mass = 2.8 g Volume = 3.67 mL
D = 2.8g/3.67 mL= 0.76 g/mL
This object would float in water because its density is less than water (1.0 g/mL).

10. Density Practice
What is the density of a block of marble that occupies 310 cm3 and has a mass of 853 g?

11. Density Practice
A car engine has a mass of kg. If the engine has a volume of 4.5 L, what is its density?

12. Density Practice
Diamond has a density of 3.26 g/cm3. What is the mass of a diamond that has a volume of 0.35 cm3?

13. Density Practice
What is the volume of a sample of liquid mercury that has a mass of 76.2 grams, given that the density of mercury is g/mL?

14. More Density Calculations
Ex: A liquid has a mass of 25.6 g and a volume of 31.6 mL. Use the table below to identify the substance.
M=25.6 g V=31.6 mL
D = 25.6 g/31.6 mL
D= 0.81 g/mL
The substance is ethanol.

15. Physical and Chemical Changes
Unit II—Part 2

16. Concept of Change
Change: the act of altering a substance

17. Physical Change
Physical change: a change that occurs that does not change the identity of the substance
Phase Changes
Tearing paper
Crushing Rocks

18. Chemical Changes
Chemical change: a change that occurs causing the identity of the substance to change
Burning
Digesting food
Reacting with other substances
(give an example per reviewer)
A chemical change is called a chemical reaction

19. Chemical Changes Cont’d
Indicators of a chemical change:
Evolution of light
Evolution of heat (produced or absorbed)
Evolution of a gas/change in odor
Color change (careful here)
Formation of a precipitate

20. Is it Physical or Chemical?
Change
Physical
Chemical
Melting cheese
Burning wood
Milk souring
(Do all students relate to this?)
Wadding up paper
Bicycle rusting