WHMIS symbols: what does WHMIS stand for? Why is it an important safety feature? Why do we use symbols and not just words? , The particle model of matter – temperature and dissolving solutes Particles within a substance will move faster when you increase the temperature. Spaces between particles Attraction forces between particles Each pure substance have their own identical particles Classification of Matter Mixtures Mechanical mixtures: Contains two of more visible parts (chocolate chip cookie) Colloids: cloudy-cause Tyndal effect. (milk, mayo, clouds, fog..) Suspension: Large particles that are uniformly mixed but will settle out with time. Can be separated by filtering (dirty air, tomato juice…) Solutions: Contains two or more particles that are uniformly scattered and appear to be one. (apple juice, clean air, …..) Pure substances: properties will always remain the same. Substances composed of one type of atom or only one kind of particle. Elements: Composed of one type of atom (oxygen, hydrogen, pure gold/silver, ..) Compounds: composed of two or more elements in a fixed ratio (baking soda, pure water, salt, sugar,…) Classify MIXTURES by: Homogeneous: Is a solution that looks as if it is all one substance. Heterogeneous: When you can see the different substances that make up the mixture. Solutions: Contains two or more particles that are uniformly scattered and appear to be one. When one substance dissolved or disappears in another substance and their properties are blended. Solutes : What is being dissolved (smaller proportion-can have many solutes) Solvents: What is doing the dissolving (largest proportion-only one) Dilute solutions (very little solute dissolved) vs. concentrated solutions (lots of solute dissolved) Unsaturated solution (can hold more solute) vs. Saturated solution (cannot hold any more solute) Super-saturated solutions: When no more solute can be dissolved in a solvent. The solution contains more solute than it can normally hold at a certain temperature. Concentration of a solution: 24grams of solute in 100mL of solvent (24g/100mL) SOLUBILITY: maximum amount of solute dissolved into a certain amount of solvent at a certain temperature. (24g/100mL @ 25˚C) What affects solubility of a solution? The type of solute, the type of solvent, temperature. Use particle theory to explain each one. Rate of Dissolving: What three factors affect the rate of dissolving? Stirring, temperature, smaller particles of solute (more surface area). Use particle theory to explain why each one increases or decreases the rate of dissolving. - Size of pieces – Small pieces of solute dissolves more quickly than large pieces. All the smaller pieces together have more surface area among them for the solvent particles to bump into. -stirring and increasing the temperature increases the speed at which the particles are moving thus allowing attractions between the solute and solvent to occur faster. Properties of Fluids: Fluids are……… Viscosity – What is it? What particle theory is responsible for viscosity? How do we measure viscosity? How does temperature affect a fluids’ viscosity? (As the temperature of the liquid increases, the particles speed up and the viscosity decreases. As the temperature of the liquid decreases, the particles slow down and the viscosity increases.) Density: Measuring density 𝑀𝑎𝑠𝑠 (𝑚) Density (d) = 𝑉𝑜𝑙𝑢𝑚𝑒 (𝑣) Unit of measurement g/mL (liquids) or g/cm3 (solids) -How do we use density to identify an unknown substance? -Can you calculate the density of a solid? Liquid? In a lab set-up? -How can you change the density of a solution? Adding salt to water increases the number of particles in a given volume. Increasing the concentration of salt, increases density Changing the temperature so particles are closer or farther apart. Which fluid has a higher density? Which fluid has a lower density? Can you calculate density from a graph? -Can you use a hydrometer to find density of a liquid? Buoyancy in lakes and oceans -how can you use density to understand buoyancy? (fresh water vs. salt water) -Less dense objects float in more dense substances. -What is Buoyant force? Pushes objects in a direction opposite to the force of gravity. -Gravitational pull vs. buoyant force. What will happen to an object when the gravitational pull on an object is greater than the buoyant force? -Plimsoll Line on boats are used for? Measuring pressure – unit of measurement is Pascals Compression of fluids: Gases can be compressed the most -A pascal equals the force of 1N (newton) over an area of 1m2. 1𝑁 -1 Pa= 1𝑚2 -1 pascal equals the force of 1 N -A fluid at rest will exert pressure in all different directions Pascal’s Law. -How is pressure affected by depth/altitude? Scuba diving vs. flying in a plane -What happens when there is a pressure change? -Hydraulic devices – How do these machines work? Hydraulics use _______ under pressure to move large objects. Can you calculate the pressure inside the hydraulic device or the force it can exert on the output piston? -Other devices that use hydraulics are: back hoe, dump truck, …. 20 000N 400N 5 cm2 ??????????? -Pneumatic systems use ________ under compression to move an object. Examples are:, jack hammer, dentist drill, bus doors … -Why are pneumatics more beneficial than hydraulics? Match the following with the correct unit of measurement: density of a solid mL volume of a liquid g/cm3 density of a liquid g/mL mass g Force N Air flow in a submarine o To dive - the submarine releases air from the ballast tanks and allow seawater to enter. The density of the submarine becomes greater than the water on the outside. o To resurface – Compressed air is forced into the ballast tanks through the valves at the top. This forces the seawater out of the bottom valves. The density of the submarine with air in the tanks becomes less than the density of the water, so the submarine rises to the surface. LABS: o Manipulated Variable : The variable that is changed in a lab o Responding Variable: the variable that you are trying to find out—the results of changing the manipulated variable. o Controlled variables: all other variables that are kept the same to ensure the responding variable is due to the manipulated variable and nothing else!!! REVIEW LAB STATIONS: STATION 1: WHMIS AND PARTICLE MODEL OF MATTER: Work through first three slides on computer—notebook (review notes for Unit Final) STATION 2: CLASSIFICATION OF MATTER: Look at the classification names and definitions. Match the definitions to the category name. Then classify the examples. When done check your answers to the answer key! Mix up sheets when done so it is ready for the next group. STATION 3: SOLUTIONS: DILUTE, CONCENTRATED, UNSATURATED, SATURATED Match the definitions to the appropriate word. Match the examples to the definitions. When done check your answers to the answer key! Mix up sheets when done so it is ready for the next group. STATION 4: SOLUBILITY-AFFECTS ON SOLUBILITY Follow the directions at the station. STATION 5: RATE OF DISSOLVING: Follow the directions at the station. STATION 6: VISCOSITY: Follow the directions at the station. STATION 7: DENSITY: Follow the directions at the station. STATION 8: BUOYANCY: Follow the directions at the station. STATION 9: PRESSURE: Follow the directions at the station. STATION 10: TECHNOLOGY: Follow the directions at the station.