Unit 1: Mix and Flow of Matter

1
Unit 1 Mix and Flow of Matter

• Grade 8 Science
• Mr. Chin

2
WHMIS

• WHMIS Workplace Hazardous Materials Information
  System

3
Topic 1 The States of Matter

• Solid has definite shape and volume
• Particles in a solid are tightly packed together.
  The cannot move around freely, they can only
  vibrate.
• Examples??

4
Continued

• Liquid has a definite volume but no definite
  shape.
• Particles in a liquid have enough energy to slide
  past one another while they vibrate together in
  clusters.
• Examples??

5
Continued

• Gas has no definite shape or volume
• Enormous amounts of empty space between
  particles, they, like liquids will take the shape
  of their container.
• Examples??

6
Continued

• Plasma Makes up approximately 98 of the
  universe, however there is very little on earth.
  
• Plasma is a gas-like mixture of positively and
  negatively charged particles.
• Examples lightning, auroras, neon signs

7
Particle Model of Matter

• The Five Main Points
• All substances are made of matter
• All particles in a pure substance are the same.
  Different pure substances are made of different
  particles.
• Particles are always in motion. The speed of the
  particles increases when temperature increases.
• Particles have space between them
• There are attractive forces between particles

8
Changes of State
9
Topic 2 Mixing and Dissolving

• Classification of Matter

10
Pure Substances

• All pure substances contain only one type of
  particle.
• They can exist in three states of matter solid,
  liquid and gas.
• Examples of Elements??
• Examples of Compounds??

11
Mixtures

• Mixtures contain two or more pure substances
• Homogeneous Mixtures Look as though they only
  have one substance.
• E.g. Kool-aid, Hot chocolate
• A homogeneous mixture where no settling occurs is
  called a solution

12
Mixtures Continued

• Heterogeneous Mixtures Mixtures that contain two
  or more parts that are still visible.
• Examples??

13
Mixtures Continued

• In-Between Mixtures
• Suspension A heterogeneous mixture in which the
  particles settle slowly. E.g. salad dressing
• Colloid A heterogeneous mixture in which the
  particles do not settle. E.g. Smoke, dust
• Emulsion A mixture in which droplets of fat are
  prevented from joining together by an emulsifying
  agent. E.g. Mayonnaise

14
Dissolving

• Dissolving The complete intermingling of the
  particles of two or more substances.
• Solute The substance that dissolves in the
  solvent to form a solution. There is usually less
  solute than solvent in a solution.
• Solvent The substance that dissolves a solute to
  form a solution. There is usually more solvent
  than solute.
• You dissolve salt in water. Which is the solute??
  Which is the solvent??

15
Continued

• Soluble means able to dissolve in a particular
  solvent
• Insoluble means unable to dissolve in a
  particular solvent
• Give an example of a substance that is soluble in
  water?
• Give an example of a substance that is insoluble
  in water?

16
Factors That Affect Dissolving

• Agitation
• Solute Size
• Temperature
• Pressure
• Why do you think these factors can affect
  dissolving?

17
Solubility

• Solubility The mass of a solute that can
  dissolve in a given amount of solvent to form a
  saturated solution at a given temperature.
• How much can be dissolved??
• Saturated No more solute will dissolve in a
  specific amount of solvent at a specific
  temperature.
• Supersaturated A solution that contains more
  solute than would normally dissolve at a certain
  temperature.

18
Continued
Substance Solubility (g/100g Water) at Solubility (g/100g Water) at Solubility (g/100g Water) at Solubility (g/100g Water) at Solubility (g/100g Water) at Solubility (g/100g Water) at
Substance 0oC 20oC 40oC 60oC 80oC 100oC
Copper Sulfate 15 20 30 40 55 79
Lithium Sulfate 35 35 33 31 30 29
Ammonium Chloride 30 38 45 55 65 78

1. Which substance has the greatest solubility at
   80oC?
2. Which solution is saturated at 60oC, with 40g
   dissolved in 100g of water?
3. Mr. Chin wants to add 2g of Copper sulfate to a
   solution that already contains 14g of copper
   sulfate/ 100 g of water at 0oC. What will happen??

19
Solubility
20
Topic 3 Viscosity Density

• Viscosity How thick or thin a liquid is. A thick
  liquid is more viscous and has a higher
  viscosity.
• Give examples of liquids with high viscosity.
• Give examples of liquids with low viscosity.
• Flow Rate The time it takes for a liquid to flow
  from one point to another.

21
The Effect of Temperature on Viscosity of Liquids

• Warmer liquids flow quickly
• Cooler liquids flow slowly
• Examples??
• ThereforeThe viscosity of a liquid _________ as
  it is heated and _________ as it is cooled.

22
The Effect of Temperature on Viscosity of Gases

• Hotter air particles have more collisions than
  cooler ones.
• More collisions would cause them to move
• Therefore The viscosity of a gas _________ as it
  is heated, and _________ as it is cooled.

23
Density

• Density Mass per unit volume of a substance.
  Particle Crowdedness
• Mass The amount of matter in a substance
  (particles)
• Volume Measurement of the space taken up by a
  substance
• Weight Force of gravity on an object
• Force A stress such as a push or pull
• What is the difference between weight and mass????

24
Formula for Density

• Density Mass Volume
• D M/V
• 1. Concentrated sugar could have a mass of 10g
  and take up a volume of 2cm3. So the density
  would be
• D M/V
• ???

25
Density of Materials

• In general, gases are less dense than liquids and
  liquids are less dense than solids of the same
  substance.
• Explain
• Does that mean all solids are more dense than all
  liquids?
• Can you think of any exceptions? How do you know??

26
Ice Crystals
27
Density
Fluid Density (g/ml) Solid Density (g/cm3)
water 1.00 Cork 0.24
seawater 1.03 Oak 0.70
mercury 13.55 Sugar 1.59

1. Which fluid has the lowest density?
2. Which fluid has the highest density?
3. Which solid would sink in seawater?
4. Which solid would sink in mercury?

28
Buoyancy

• Buoyancy is the tendency for materials to rise
  or float in fluid. It is the ability of a fluid
  to support an object floating in or on the fluid.
• Average Density The total mass of all substances
  on board divided by total volume.
• Even steel ships can float provided they have a
  hollow hull.
• It can be used to help floating objects sink too.
  A fish bladder enables a fish to increase or
  decrease their density by adding or removing air.

29
Average Density

• Using the principle of Average Density explain
  how a Hot Air Balloon works

30
Changes in Buoyancy

• Why is it so much easier to float in the Dead Sea
  than in any other ocean?

31
Archimedes Principle

• Archimedes was a Greek scientist around 212 BC.
• Archimedes Principle The buoyant force acting on
  an object equals the weight (force of gravity) of
  the fluid displaced by the object!
• What does that mean??

32
Archimedes Principle

• Archimedes. Principle
• - states that the buoyant force acting on an
  object equals the weight (force of gravity) of
  the fluid displaced by the object.
• - used his own body (which displaced water in the
  bathtub) to prove the kings goldsmith was
  cheating the king
• - the buoyant force does not depend on the weight
  of the submerged
• object, but rather on the weight of the displaced
  fluid

33
Neutral Buoyancy

• If the water in a container is still, or at rest,
  then the water particles are neither rising nor
  sinking. An object immersed in a fluid such as
  water does not rise or sink if the amount of
  force pulling down (gravity) equals the amount of
  force pushing up (buoyancy).
• When gravity buoyancy its called neutral
  buoyancy.

34
Question??

• Why do you sink the bathtub but float in the
  ocean??

35
Pressure

• Pressure Force Area
• P F/A
• Force is measured in Newtons and area is usually
  measured in m2. The unit for pressure therefore
  is N/m2. This is also called a Pascal (Pa) for
  the man who invented it.
• A kilopascal equals???

36
Applications of Pressure

• Water hoses
• Fire extinguishers
• High heels!
• Cushioning materials
• All-terrain vehicles
• Other examples???

37
Compression of a Gas

• The gas must be enclosed in a sealed container
  with sturdy walls
• There is so much space between particles that
  even if they are squeezed together they will
  still behave as a gas
• An external or outside force is applied to the
  enclosed gas to push the particles closer
  together.
• The great thing about applying force to a
  compressed gas is that there is a counter force
  which acts as a cushion. This is used in shocks
  and airbags in a car.

38
Balanced and Unbalanced Forces

• The Earths atmosphere is 160km thick and is held
  to the earth by gravity. The pressure of the
  weight of all that air is called atmospheric
  pressure. When you change altitude, you often
  feel a pop in your ear this is the pressure
  equalizing on either side of your eardrum.
• Balanced and Unbalanced Forces In a Container
• Too much force inside, not enough outside
  EXPLOSION
• Too much force outside, not enough inside
  IMPLOSION

39
Technologies based on Solubility

• Separation Methods
• Desalination Water is separated from a solvent
  via evaporation. The solvent (water) is recovered
  but the solute isnt necessarily.
• Distillation Boiling water allows it to be
  separated from a mixture and have each collected
  in different containers, leaving a distillate
  (water) and residue.

40
More Separation Methods

• Filtering Materials are screened out leaving a
  filtrate and residue.
• Underground Solids Material is crushed and
  dissolved, waste material is removed via a system
  of filters and the wanted mineral is left behind.
  
• E.g. Gold

41
Other Technologies

• Convenience foods are often dehydrated, so they
  can be stored for long periods of time without
  spoiling (you just add water when you want to use
  it)

42
Technologies Based on Viscosity and Flow Rate

• Lipstick solvents, oils and waxes are mixed in
  such a way that their viscosity is increased so
  lipstick is solid.
• Gravy
• Paint
• Other examples???

43
Technologies for Moving Fluids

• Hydraulic Systems Are devices that apply
  force/pressure to a liquid to move something
  else. E.g. water pump, oil and gas pipeline
• Pneumatic Systems Are similar to hydraulic
  systems except gases are used instead of liquids.
  E.g. Dentist drill, jack hammer
• Compressor A device that compresses air