Post on 08-Oct-2020
Introduction to 4.2
What’s so Special about Paper Clips?
Activity 4-4 p.150
4.2 Physical Properties
Physical Properties
Characteristic of a substance
Can be observed and measured without changing the identity of the substance
Physical Properties
2. Quantitative1. Qualitative
1. Qualitative Physical Properties
Can be observed and described without detailed measurement
Property Examples
Colour colourless, red, black
Odour sweet, pungent, mouldy
State solid, liquid, gas
Texture rough, smooth, bumpy
Lustre shiny, dull
Malleability soft, pliable, hard
2. Quantitative Physical Properties
Can be measured and assigned a particular value
Property Description
viscosity resistance to flow
melting point temperature of melting
boiling point temperature of boiling
solubility ability to dissolve in another substance
hardness ability to scratch another material
conductivity ability to conduct electricity or heat
density ratio of mass to volume
Physical Properties
states of matter
melting and boiling points
solubility
hardness
conductivity
density
States of Matter
A qualitative physical property
Gas
Solid
liquid
Melting and Boiling Points
A quantitative physical property
Melting point is the temperature at which a solid turns into a liquid
Boiling point is the temperature at which a liquid turns into a gas
Solubility
A quantitative physical property
Measures the ability of a substance to dissolve in another substance
The maximum quantity of a substance that can dissolve
in a given amount of solvent
at a particular temperature and pressure
Solubility
Example: sodium chloride (table salt)
39.5 g/100 mL in water at 25 °C and atmospheric pressure
Solubility
Aqueous solution is a solution with water as a solvent
Insoluble means does not dissolve or has a very low solubility
Examples: copper in water
Solubility Fat can be a solvent
Some chemicals dissolve in fats
eg. DDT (dichloro-diphenyl-trichloroethane)
a synthetic pesticide
bioaccumulates and biomagnifies in mammals
Hardness
A quantitative physical property
Ability to scratch another material
Between 1 to 10 on the Mohs scale
Fingernail --- 2
Diamond --- 10 (the hardest natural material)
Conductivity
A quantitative physical property
Ability to conduct electricity or heat
Copper: conducts electric current very well
Aluminum: conducts heat very well
Density
A quantitative physical property
The ratio of the mass of a substance to the volume it occupies
Oil flows on water
Iron nails sinks in water
A cruise ship floats on the sea water
All three phases exists on Earth
Universal solvent
Can absorb a lot of heat before it gets hot
Its solid form is less dense than its liquid form(ice acts as an insulator for water below)
Water’s Unique Physical Properties
Learning Check
What is the difference between qualitative physical properties and quantitative physical properties?
How could knowing the melting points of two pure substances that look alike help you tell the substances apart?
Why do people often check to see if a diamond is real by rubbing it against glass?
DEMO: Density Tube
Density
Unit for density is g/cm3
Density = mass
volume
D = m
V
Sample Problem
A sample of silver has a mass of 5.04 g and a volume of 0.480 cm3. What is the density of silver?
Practice Problems
Page 157 #1-5
Homework
P.159 #1-8