p. 178  Q2: Why does water change from a solid to liquid when it is heated? (WRT particle theory)  Q3: 3 examples of a pure substances.  Q4: 3 examples of a mixture  Q5: describe mechanical mixture  Q6: describe a solution.

p. 178  Q8: MM or S?  Pane of clear glass  Chocolate chip ice cream  Clear apple juice  A pizza  Garbage in a garbage can  Q9: what kind of alloy makes an effective solder material? (Sn and Pb)  Q10: Lead is not used in solder anymore, why?

Making Observations and Inferences

Observations Observations: Using our senses to gather information about the world around us. There are two types of observations.

Qualitative Qualitative observation: (quality) Usually made with our senses. Color, shape, feel, taste, sound. Examples: Olivia is wearing a blue sweater. The lab tabletop is smooth. The dog’s fur is shiny.

Quantitative Quantitative observation: (quantity) How many. Will always have a number. Based on exact measurement. Examples: The room is 8 meters across. Sarah is 141 cm tall. Sam weighs 450 Newtons.

Inferences Inference: A logical interpretation of an event that is based on observations and prior knowledge.

Making Inferences You are at the counter in the office to get a bus pass signed. You see a student leave the principal’s office crying and upset. We could make an inference as to why the student is upset.  Could be in trouble  Student not feeling well  Student has poor grades

Observation vs. Inferences  Observation – Based on the five senses: Sight, Smell, Touch, Taste, Hearing  Inference – Based on prior knowledge or opinion  In laboratory exercises, record observations NOT inferences  Inferences may be used when writing the conclusion in your lab report.

Observation vs. Inferences

Does the square have curved sides?

Where are those dots coming from?!

Can you pick the tallest soldier?

These circles are not moving!

Are these dots moving?

Take a good look at the following picture

Questions: Q1: Are there cars parked on the sides of the road? Q2: What color is the pickup truck driving in the road? Q3: Are there any minivans around? Q4: What does the blue sign say? Q5: What’s the speed limit? Q6: Are there any pedestrians on the road?

Questions: Q1: Are there cars parked on the sides of the road? YES Q2: What color is the pickup truck driving in the road? BLUE Q3: Are there any minivans around? YES Q4: What does the blue sign say? Yard Sale Q5: What’s the speed limit? 35 mph Q6: Are there any pedestrians on the road? No

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Variables  Independent variable: The variable being tested  Dependent variable: The variable that changes (what happens during the experiment)  Control variable: A ‘normal’ variable. Used for comparison.  Hypothesis: An educated guess If INDEPENDENT VARIABLE, then DEPENDENT VARIABLE

The Problem/Purpose Mrs. Soloman (the Principal) believes that a special juice from GNC health foods will increase the productivity of teachers at John Fraser SS. She creates two groups of 50 teachers each. One group will drink the 'special juice' and the other will drink water with blue food colouring. The task she asks them to complete is stapling sets of paper together. After one hour Mrs. Soloman counts how many sets of papers were stapled by each group.

Identifying Important Information Mrs. Soloman (the Principal) believes that a special juice from GNC health foods will increase the productivity of teachers at John Fraser SS. She creates two groups of 50 teachers each. One group will drink the 'special juice' and the other will drink water with blue food colouring. The task she asks them to complete is stapling sets of paper together. After one hour Mrs. Soloman counts how many sets of papers were stapled by each group. Control variable:Group that drinks water Independent variable:Special juice Dependent variable:Productivity of teachers What would be an appropriate hypothesis for this experiment?

The Problem/Purpose Mr. Chawla notices that his shower is covered in green slime. Miss. Adams suggests that Mr. C use coconut oil to get rid of the slime. Mr. C decides to use the coconut oil on half the shower and plain water on the other. After three days of 'treatment' there is no improvement with respect to the slime. Identify the control variable; independent variable and dependent variable What should Mr. C's conclusion be?

The Problem/Purpose Mr. Miller wants to test whether a new hair growth treatment works. He decides to use Hair for the Head (hair growth cream) on half of his head and leaves the other side bare. Identify the control variable; independent variable and dependent variable What would be an appropriate hypothesis for this problem? REMEMBER THE RULE FOR WRITING HYPOTHESIS! If independent variable, then dependent variable

Observations and Inferences Examples 1. The concert was loud 2. There are 35 students in the class 3. When a student gets sent to the office it means they are in trouble 4. Yao Ming is 7 feet 6 inches tall 5. The chemical smelled like sulfur 6. First period on day 1 is 115 minutes 7. Students at Stephen Lewis are smart 8. The water is cold 9. Tall people are good at sports 10. A large coffee from Tim Horton's costs $1.52

Chemical Versus Physical Properties Chemical Properties  A characteristic of a substance that is determined when the composition of the substance is changed and one or more new substances are produced.  Examples: combustibility, reactivity Physical Properties  A characteristic of a substance that can be determined without changing the composition of that substance.  Examples: Lustre (shininess/dullness), optical clarity (transparent, translucent, opaque), brittleness (breakability), viscosity (resistance to flow)

Chemical Versus Physical Changes Chemical Changes  Bubbles form (gas production)***  A new colour appears  Heat or light is given off  A precipitate forms ***  The change is difficult to reverse Physical Changes  A change that affects the size, shape or colour of a substance but does not affect its composition

Activities Stations 1-5  Identify the particular chemical/physical property of the substance at each station.  Write one sentence explaining your answer Stations 6-10  Follow the procedures at each station.  Identify the reaction as physical or chemical  Write one sentence explaining you answer P. 182 Q: 2, 4, 5 P. 186 Q: 2 - 7