4.2 physical properties (pages 149-159) homework: pages 159 # 2-7 page 155 activity investigation 4
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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:
• Separation of Liquids Based on Density
V
mD
• 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 MatterColour red, black, blue Sulfur is yellow.
Odour pungent, mouldy The fruit smells mouldy
State solid, liquid, gas Water is liquid.
Texture rough, smooth Sand paper is rough.
Lustre shiny, dull Diamonds are shiny.
Malleability pliable 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 The solubility of NaCl
another substance is 39.5g/100mL.
Hardness ability to scratch another Diamond is the hardest
material substance.
Conductivity ability to conduct Metals are good conductors
electricity and heat of electricity and heat
Density ratio of mass to volume The density of water
D = m / V 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: Paraphrase:
m = 21.6g d = m Therefore, the density
v = 8.00 cm3 v of the unknown metal
d = ? = 21.6g 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: Solution: Paraphrase:
m = 101g d = m Therefore, the
v = 95.5cm3 v density of the
d = ? = 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.