Science 8 Unit A Mix and Flow of Matter

1.1 WHMIS Symbols and Safety Procedures Hazard symbols found on items in your home have a safety symbol and a shape to indicate how hazardous a substance is The shapes: A yellow triangle: ‘caution’ An orange diamond: ‘warning’ A red octagon: ‘danger’

The symbols: flammable toxic electrical explosive irritant corrosive biological

WHMIS (Workplace Hazardous Materials Information System) WHMIS symbols are used to protect people at work. They are: Compressed gas Dangerously reactive material Oxidizing material

Poisonous and infectious causing immediate and serious toxic effects Flammable and combustible material Biohazardous infectious material Corrosive material Poisonous and infectious causing other toxic effects

Safety Rules Read all written instructions before doing an activity Listen to all instructions and follow them carefully Wash your hands carefully after each activity and after handling chemicals Wear safety goggles, gloves, or an apron as required Think before you touch; equipment may be hot and substances may be dangerous

Smell a substance by fanning the smell toward you with your hand; do not put your nose close to the substance Do not taste anything in the lab Tie back loose hair and roll up loose sleeves Never pour liquids into containers held in your hand; place a test tube in a rack before pouring substances in it Clean up any spilled substances immediately as instructed by your teacher Never look into test tubes or containers from the top; always look through the sides

Never use cracked or broken glassware; make sure you follow your teacher’s instructions when getting rid of any broken glass Label any container you put chemicals in Report all accidents and spills immediately to your teacher If there are WHMIS safety symbols on any chemical you will be using, make sure you understand all the symbols **Show respect and concern for your own safety and the safety of others**

1.2 Many Uses of Fluids A fluid is anything that has no fixed shape and flows Slurry technology uses water to transport solids Ex. Washing sand off your driveway; transporting oil sands in a pipeline

Many items are originally prepared as a fluid Ex. Glass is heated until it is a fluid, allowing it to be shaped Fluids can hold other materials Ex. Toothpaste holds detergent and fluoride

2.1 Pure Substances and Mixtures * All matter is either a pure substance or a mixture Pure Substances Made up of one type of matter Have a unique set of characteristics Cannot be separated into different substances Ex. aluminum foil, baking soda, distilled water Mixtures Two or more substances combined together Ex. pop, mixed vegetables, cookies

Types of Mixtures Mechanical Mixture (or Heterogeneous Mixture) – in this type you can see the different parts that make the mixture; ex. soil and mixed vegetables Solutions (or Homogeneous Mixture) – a mixture that appears to be one substance; difficult to tell the difference between a solution and a pure substance without performing tests; ex. pop and vinegar

Suspension – is a cloudy mixture in which droplets of one substance are held within another substance; if you leave the substance undisturbed, its parts will usually separate out; ex. muddy water, tomato juice Colloid – also a cloudy mixture but the droplets are so small that they will not separate out easily; ex. milk

2.2 Concentration and Solubility Dissolving one substance into another is called a solution The substance that dissolves is called the solute The substance that does the dissolving is called the solvent

There will almost always be more of the solvent than the solute ex. making orange juice from concentrate - add the concentrate (solute) to a large amount of water (solvent)

Measuring Concentration The concentration of a solution tells you the amount of solute dissolved in a specific amount of solvent For example, a solution with 50 g of solute dissolved in 100 mL of water has a concentration of 50g/100mL of water

Saturated and Unsaturated Solutions An unsaturated solution is one in which more solute can dissolve A saturated solution is a solution in which no more solute can dissolve at a given temperature The saturation point is the point where an unsaturated solution changes to a saturated solution

Paper Chromatography The paper chromatography test can be used to determine if something is a pure substance or a solution Place a piece of filter paper in a substance If the fluid moves up the filter paper and stops at one level, it is a pure substance If it moves up to different levels, it is a solution

2.3 Factors Affecting Solubility Recall: Solubility is the maximum amount of solute you can dissolve in a given amount of solvent Solubility depends on three factors: type of solute, type of solvent, and temperature Types of Solutes and Solvents Water is the universal solvent because it is so commonly used; the term aqueous solution means the solvent is water Solutions can be made of solids, liquids, or gases

Temperature Solubility of liquids and solids usually increases as the temperature of the solvent increases For gases, as the temperature increases, solubility decreases

Thermal Pollution Industrial plants use water from rivers and lakes Before they return the water, it is stored in a cooling pond If the returned water is warmer, the solubility of oxygen decreases  there will be less oxygen

2.4 Particle Model of Matter and Mixtures The Particle Model of Matter 1. All matter is made up of tiny particles. Different substances are made of different particles. In a given volume, there are more particles (that are too small to be seen) of a solid than of a liquid or gas.

2. The tiny particles of matter are always moving and vibrating. For solids, this movement is a vibration in place. For liquids, the particles slide around and over each other. For gases, the movement is as far as the space allows.

4. The particles have spaces between them. 3. The particles in matter may be attracted to each other or bonded together. 4. The particles have spaces between them. More space between particles of a gas than in a solid or liquid.

Explaining Mixtures When two substances are mixed together, the smaller particles of one substance fill in the spaces between the larger particles of the other; this is why the volume might not change In a solution, if the particles of the solute are attracted to the particles of the solvent, the solute will dissolve in the solvent (seems to disappear)

Factors Affecting the Rate of Dissolving Temperature Particles move faster in higher temperatures, bumping into each other more often Size of Pieces Smaller pieces dissolve faster since they have more surface area for the solvent to bump into Stirring Moves particles around, causing solvent and solute particles to bump into each other

3.1 Viscosity and Temperature ** Remember: Fluids are anything that flow and have no fixed shape – can be liquids, gases, etc. Think of three fluids you have used and what they would be like if they were thicker or thinner Fluid Thicker Thinner

Viscosity refers to how quickly fluids flow; it is determined by internal resistance or friction that keeps it from flowing The more the particles rub together, the greater the friction and the greater the viscosity A high viscosity means fluids do not flow easily Ex. juice – low viscosity; ketchup – high viscosity

What effect does temperature have on viscosity? Cooking oil placed in the fridge Syrup poured over hot pancakes Engine oil poured into a hot engine Hot tar spread on a road

As the temperature of a fluid increases, the viscosity decreases and vice versa When energy (heat) is added, the particles move around more; when the temperature falls, the particles slow down The ‘ramp method’ is used to measure viscosity – pour a fluid down a ramp and time how long it takes to get to the bottom

http://www.youtube.com/watch?v=7Ft9VD DPWb4&feature=related http://www.youtube.com/watch?v=vNzTYzj LgKE

3.2 Density Density is the amount of matter in a given volume; depends on the type of particles If the density of an object is greater than the density of the fluid it is in, the object will sink; if the object is less dense than the fluid, the object will float Ex. Wood floats and rocks sink in water

To calculate: Density (d) = Mass (m) Volume (V) Units g/mL or g/cm3 Ex. You have 3.5 mL of oil and it has a mass of 6.5 g. What is the density? Answer = 1.9 g/mL

http://www.youtube.com/watch?v=fqLCwu KMBMA “Egg Density Experiment” http://www.youtube.com/watch?v=5HCmR CGv37s&feature=related “Float or Sink”

If a boat is heavier than water, why does it float If a boat is heavier than water, why does it float? It has to do with average density. Each of the materials making up the boat might sink in water but the average density of the whole boat is less than the density of water. The average density of the boat includes not only the solid parts but also the air throughout the boat.

3.3 Density, Buoyancy, and Temperature Density does not change as long as temperature stays the same As temperature increases, density decreases Particles are moving faster, causing volume to increase Substances (except water) have a greater density as a solid than as a liquid or gas By adding more particles, you increase the density of the substance  more dense objects can float (ex. adding salt to water)

Buoyancy is the tendency of an object to float; the buoyant force is the force acting against gravity When an object is in a liquid, gravity pulls it down and the buoyant force pushes it up If the buoyant force is greater than gravity, the object floats (and vice versa)

What is a Plimsoll line? Ships have a Plimsoll line painted on their hulls. It shows how heavy a ship can be safely loaded in different water conditions (ships float lower or higher depending on the type of water).

How do hot air balloons work? Hot air balloons heat air, making it less dense than the surrounding air. The buoyant force pushes it up until the buoyant force equals the force of gravity.

3.4 – Compression of Fluids When a force pushes on an object, the object is said to be under compression Objects under compression seem to deform in shape Ex. When you kick a soccer ball, the force of your foot compresses the ball and temporarily deforms it

Differences in Compressibility Between Gases and Liquids Gases are more compressible than liquids There is more space between the particles in a gas so they have greater room to move closer together Materials in a liquid state are incompressible (they cannot be compressed easily) Ex. Pop bottle full of liquid or pop bottle full of air

Pressure (p) = Force (F) 3.5 – Pressure in Fluids Pressure is the amount of force applied to a given area Pressure (p) = Force (F) Area (A) Units: Force – Newtons (N) Area – m2 Pressure – Pascals (Pa) 1 Pa = 1 N m2 Ex. You have a force of 10 N on an area of 2 m2. What is the pressure?

Pressure and Depth “The greater the depth, the greater the pressure” If a fluid is in a container, the fluid at the bottom will have greater pressure on it than the fluid at the top The fluid at the bottom has the weight of the fluid at the top pushing down on it

Pascal’s Law Pascal’s Law states that an enclosed fluid transmits pressure equally in all directions. This is useful in hydraulic and pneumatic devices Hydraulic and Pneumatic Devices Hydraulic systems use a liquid as the enclosed fluid Pneumatic systems use air as the enclosed fluid

4.1 Technology Based on Solubility A detergent is a substance that can remove dirt from fabric They contain surfactants  particles that attach themselves to dirt and oil, separating them from fabrics Phosphates were used but damaged the environment (polluted water)

How Detergents Work There is dirt and grease on fabric Water, detergent, and clothes are agitated in the machine; dirt breaks off clothes Surfactants attach to dirt so they can’t re-attach to clothes

Diving Nitrogen gas gets dissolved into blood at a higher concentration than normal If a diver ascends to the surface slowly, the extra gas leaves the body as the pressure changes

If a diver goes too quickly, the pressure change is too rapid; called ‘the bends’ It causes nitrogen to collect in body parts, causing severe pain; death can result if untreated A hyperbaric (high pressure) chamber can be used to treat ‘the bends’

4.2 Technology Based on Flow Rate A pump is a device that moves a fluid through or into something A bicycle pump has a piston that moves up and down in a cylinder As the piston moves up, air fills the cylinder; when it is moved down, the air is compressed and the pressure increases The air moves to a lower pressure area (the object being pumped up)

In pipelines, pumps push fluids along at a steady rate In natural gas pipelines, the pressure keeps the pipeline clean A computerized unit (a ‘pig’) is pushed through the moving gas, cleaning the pipes and recording its condition

Valves regulate the amount of fluid flowing Ex. Water tap Valves can also control the level of fluid in a container Ex. A valve in a toilet tank that closes off the flow of water when the water is at the right level

4.3 Designing a Fluid-Using Device Humans cannot always dive into deep water, so underwater ships are needed The bathyscaph is an underwater ship designed to go to the deepest spot on the planet, the Marianas Trench

Submarines When the submarine is on the surface, the ballast tanks are full of air To dive, the ballast tanks release air through valves on the top; valves on the bottom open and seawater enters To resurface, compressed air is forced into the ballast tanks through the top, forcing seawater out the bottom