Transcript Physical Properties

4.2 Physical Properties (Pages 149-159)
Homework: Pages 159 # 2-7
Page 155 Activity
Investigation 4
Key Concepts: (Page 159)
• A physical property of an element or a
compound can be observed without a change
to the substance.
• Qualitative physical properties include colour,
odour, taste, texture, luster and malleability.
Quantitative physical properties include
viscosity, melting point, boiling point,
solubility, hardness, conductivity, and density.
• Physical Properties
• Density can be calculated by dividing the
mass of a substance by its volume.
The formula is: D  m
V
• Separation of Liquids Based on Density
• Diamonds are valuable as gemstones because
they have high luster, are transparent, and refract
light brilliantly.
• Diamonds are useful for industrial applications
because they are extremely hard, have very low
reactivity with chemicals, and have low electrical
conductivity.
• The unique properties of water include a
solid state that is less dense than its liquid
state, the ability to absorb a large amount
of heat, and the ability to dissolve
numerous essential chemicals and
nutrients.
Physical Properties:
• 1. Define physical property of matter?
A characteristic of a substance that can be
observed and measured without changing the
identity of the substance
Complete the Table below:
Qualitative Physical Properties
Property
Examples
Matter
Colour
Odour
State
Texture
Lustre
Malleability
red, black, blue
pungent, mouldy
solid, liquid, gas
rough, smooth
shiny, dull
pliable
Sulfur is yellow.
The fruit smells mouldy
Water is liquid.
Sand paper is rough.
Diamonds are shiny.
Gold is malleable.
Quantitative Physical Properties
Viscosity
resistance to flow
Honey has a high viscosity.
Melting point
temperature of melting
M.P. of iron is 1535°C
Boiling point
temperature of boiling
B. P of iron is 2861°C
Solubility
ability to dissolved in
another substance
The solubility of NaCl
is 39.5g/100mL.
Hardness
ability to scratch another
material
Diamond is the hardest
substance.
Conductivity
ability to conduct
electricity and heat
Metals are good conductors
of electricity and heat
Density
ratio of mass to volume
D=m/V
The density of water
is 1 g/mL or 1 g/cm3
Ductility
ability to form a wire
Copper is ductile
3. What are the three states of matter?
Solid, Liquid and Gas
4. What are the different changes of state of
matter?
Evaporation, condensation, melting, boiling,
freezing, sublimation and deposition.
)
• Copy down figure 4.8
gas
solid
liquid
6. What is solubility? How do you express
solubility of matter? What are the units
used?
• Solubility is the measure of the ability of a a
substance to dissolve in another substance.
• The solubility of a substance is expressed in
concentration.
• UNITS- mass of solute/mass of solvent
7. What is the reported solubility of sodium
chloride?
• NaCl in water at 25 °C at ATP is 39.5 g/100 mL.
8. What is an aqueous solution?
• Aqueous solution means solution with water as
a solvent. (Water is known as the universal
solvent.)
9. Differentiate between a solute and a solvent
and give two examples?
• A solute is the substance that is being
dissolved.
• Solvent is the substance that dissolves.
• Examples: salt and water, sugar and water
10. Why is diamond a precious stone? Explain its
different properties?
Majority of diamonds are used in industry.
(drilling, cutting and grinding)
Properties- high lustre, transparency, low
reactivity with chemicals, high thermal
conductivity, low electrical conductivity, and
high density.
11. Why do you think people often check to see if
diamond is real by rubbing it against glass?
Because a diamond is much harder than glass,
a diamond will not be scratched by the glass
12. Why is copper used as electrical wires?
Copper is an excellent conductor of electricity.
Problem Solving Model (G.R.A.S.P.):
• Given Note the information you are given.
• Required/Unknown: Note what you are required to
find.
• Analysis: Break the problem statement into useful
phrases for solving, then consider what formula
might be useful.
• Solution: Find the solution using all the necessary
data. Convert all units to the ones required in the
question.
• Paraphrase: Using a written statement to
summarize the meaning of the calculation. Include
your solution and the units involved.
Notes on Density:
Formula:
D =M
V
Units/Conversion: Mass (g); Volume (mL, cm
3) Density (g/mL, g/ cm 3)
Density Triangle
• Density = mass/volume
• Mass = density x volume
• Volume = mass/density
Problem Solving Model (G.R.A.S.P.):
• Given Note the information you are given.
• Required/Unknown: Note what you are required to
find.
• Analysis: Break the problem statement into useful
phrases for solving, then consider what formula
might be useful.
• Solution: Find the solution using all the necessary
data. Convert all units to the ones required in the
question.
• Paraphrase: Using a written statement to
summarize the meaning of the calculation. Include
your solution and the units involved.
13. Determine the density of the following using
the GRASP Method.
a) A sample of an unknown metal has a mass of
21.6 g and a volume of 8.00 cm3. Calculate
the density of the unknown metal.
Given/Required:
Solution:
m = 21.6g
v = 8.00 cm3
d=?
d=m
v
= 21.6g
Paraphrase:
Therefore, the density
of the unknown metal
is 2.7g/cm3.
8.00 cm3
= 2.7g/cm3
b) What is the density of a liquid if 95.5 cm3
has a mass of 101 g?
Given/Required:
m = 101g
v = 95.5cm3
d=?
Solution:
Paraphrase:
d=m
Therefore, the
v
density of the
= 101g
liquid is
95.5cm3
1.06g/cm3.
= 1.0575916
= 1.06g/cm3
c) A balloon contains 5370 cm3 of gas and has
mass of 10.24 g. The mass of the empty
balloon is 2.42 g. What is the density of the
gas?
Given/Required:
Solution:
Paraphrase:
m = 10.24g – 2.42g d = m
Therefore, the
= 7.82g
v
density of
v = 5370 cm3
= 7.82g
the gas is
d=?
5370 cm3
0.00146g/cm3.
= 0.0014562
= 0.00146g/cm3
Homework:
Complete table (d).
Mass
Volume
Density
50g
2L
25g/L
250mg
250mL
1.0mg/mL
220kg
55L
4kg/L
0.0075g
3.0L
0.0025g/L
75kg
200L
0.375kg/L
Water’s Unique Physical Properties:
14. Water is unique because the density of its solid ice is less than the
density of its liquid. Describe how life would be different if this
were not true?
• Ice wouldn't stay on the top of body of water if it was more dense than
water!
• Sinking ice would expose the underlying water to cold air temperatures
which would again freeze the water and sink
• Eventually this process would continue until a lake was completely
frozen solid
• Since most organisms cannot survive being frozen, this would create big
problems for most aquatic species!
• This "bottom ice" would be very insulated from the warm air above and
might not melt, even in the middle of the summer! The "bottom ice"
would probably kill most of the bottom organisms in the lake or river
• This would have a very bad effect on all other life in the lake that feeds
on the creatures at the bottom of the water or who use the bottom for
protection from predators
• Since large bodies of water act as tremendous heat sinks (they
moderate our climate), sinking ice may cause huge changes in the
climate, such as global warming
• 14. In a point form, summarize the different
properties of water?
- Water is the only natural substance that exists in 3
phases.
- Water is the universal solvent because it dissolves
more substances than any other liquid.
- Water can absorb a lot of heat before it can get hot.
- Water in its solid form, ice, is less dense than its
liquid form.