Convection

1. Convection Investigation 5

2. Density of Solutions • Part 1

3. Density of Fluids • Demo Bottles • Draw these two bottles in your journal and label the page Density Demo Bottles • What is happening? • Can you explain why the liquids behave the way they do? • We’ll come back to these bottle after we investigate the behaviors of liquids when they are put together. Leave plenty of space in your journal for you to add more information to this spot later.

4. A Layer of Inquiry • I have four liquids for you to investigate. • Your challenge today is to layer all four liquids in a section of straw without them mixing.

5. Materials • 4 liquids • Straws • Straw holder • Pipettes – 1 per liquid – don’t mix • Waste cup • Paper towels • Colored pencils • Lab page 21

6. Are you up to the Challenge? • Who did it? • Draw your solution on the whiteboard – one person from each table. • Color the correct solution in your journal –the title of your page should be Density of Fluids • What do you think caused the salt solutions to layer in this way? • All of the solutions are made with the same materials, water and salt. How is it that some salt solutions can be heavy and some light if they are made with the same materials?

7. Thinking about layers • Why did the fluids layer like they did yesterday? • Did you have to have it in a certain order? • Why? • All of the solutions were made out of the same materials, so why would they behave differently?

8. Density • Let’s take a look at these demonstration bottles again. • Go back to your Density Demo Bottle Page • After doing the investigation yesterday, think about and answer these questions. • How are these bottles like the investigation you did yesterday? • How are they different?

9. Frustration Bottle • This bottle has blue beads and white beads in it. • Draw a picture of the bottle and the beads. • Shake it! • Now draw the bottle again. What’s different? Why did that happen? • But wait, what is it doing now? Why? • Let’s try it again… • Explain in your journal why the stuff in this bottle behaves the way it does

10. Weight and Volume • Which is heavier, gold or feathers? Why? • Draw these two jars with their contents in your journal. • Which of these is heavier, this cup of foam cubes or this cup of beans? • How do you know? • How could you find out for sure? • The cups are the same size and they are both full. How can one be heavier than the other?

11. Class, meet Density • When you have equal volumes of material, and one is heavier than the other, the heavier material is denser. • Density is the amount of matter in a volume of material. There is a lot of matter in a volume of rock, steel, or gold. There is far less matter in an equal volume of cotton, cork, or air.

12. Density, meet my class • Density is a property of matter. All matter has density, including all solids, liquids, and gases. If you compare equal volumes of matter, and one is heavier (has more mass), the heavier volume is denser. • In the salt-solution layering activity you discovered how to layer all four solutions. • Do you think density played a role in the layering phenomenon? How?

13. Salt Solution Densities • I need 25 ml of this color in this cup • And 25 ml of this color in this cup • And 25 ml of this color in this cup • And 25 ml of this color in this cup • Label a page in your journal like above. • Draw and color in these two cups. • Will these four identical volumes of salt solutions have the same mass? If not, which one will have the greater mass? • Make a prediction for each color and write it in your journal

14. Truth Time • Weigh each of the solutions – record their masses in your journal. • Is that the exact mass of the salt solution? • What else do we have to measure? • Write the actual masses of the solutions in your journal.

15. Relative Densities • Which solution is denser? • How do you know? • If you were to layer these solutions which would be on the bottom and which would be on the top – draw and color your answer in your journal. • Is this the same as your straw layers?

16. Density Table Predict the relative densities of each of the different solutions. Add these densities to Lab Sheet 21 – Liquid Layers

17. Density Problem • I have here – two samples of salt water. Sample 1 is 45 ml, and its mass is 54 g. Sample 2 is 120 ml and its mass is 132 g. Which sample is denser? • Why?

18. So, What is Density? • Density is the ratio b/t the mass of a sample of matter and its volume. • The mass of a sample is the amount of stuff in it. You find the mass of an object or sample of material by weighing it. Mass is measured in grams.

19. And Volume too! • Volume is how much space a sample of matter occupies. All matter has volume. We measured the volume of liquids with a graduated cylinder. Solids and gases are measured in cubic centimeters. Cubic centimeters and milliliters are the same. • Density is the amount of mass per cubic centimeter. Density can be expressed as an equation We can use the equation to calculate the density of anything for which we know the mass and volume of a sample. • Density = Mass/Volume D = M/V

20. Calculating Salt Densities • Density = mass/volume • Density 1 weighs 54 g and its volume is 45 cc. What is its density. Write the formula first, then show all your math. • Density 2 weighs 132 g and its volume is 120 cc. What is its density? • Lab Sheet 23 – Pull out Lab Sheet 21 and 23, use the data from 21 to help you calculate density on 23 for each color. • Complete Lab Sheet 21/23 and turn in. • Homework – Density WS

21. Reviewing Density HW cont. • The red solution was pure water with red coloring. What is the density of water? • Which solution was densest? How do you know? • What is the relationship b/t layering and density? • What happens when you try to layer a denser solution on top of a less-dense solution?

22. Consider the following… • Pine wood has a density of 0.60 g/cc. Will it be a floater or sinker in water? Why? • Styrene plastic has a density of 1.7 g/cc. Will it be a floater or a sinker in the red solution? Why? • Now for the big test – explain these demonstration bottles using your new knowledge. • Clue – there is water in both bottles

23. Let’s Review! • The density of any object can be calculated if you know its volume and mass. • Volume can be measured in milliliters or in cubic centimeters. The unit most often used is cubic centimeters, but ml can be used with fluids. • Mass can be determined by weighing. • Density is mass per unit volume. • Always, always include units with your calculations and answers!!!!

24. Density of Solids Labs • We’re going to mess with density a little more. • Activity 1 - Pop demonstration • Activity 2 - In this lab there are two boxes of cubes made of different materials but all of the same size. All of you will need to share the cubes in order to measure the mass and volume. There are 12 cubes and four tables will share that box having 3 cubes each time. • How will you measure mass? • How will you determine volume?

25. But Wait! • You will learn to use both the triple beam scale and the electronic scale. There will be a quiz soon where you will be given an object to weigh perzactly – so make sure you are comfortable using both types.

26. Challenge • What if you had an object like this – that is not a perfect cube. How could you figure out it’s volume? • Come up with a plan with your table and be ready to share your idea. • Use the old water volume trick – • Now try it out – I have 8 objects up here that you are going to determine their density. What tools do you need? • Complete the table – you will have a limited time to determine the density of an object before I say PASS! • Use your tub for water overflow issues.

27. Weird Densities

28. Response Sheet • Let’s give you another challenge. See if you can help Rico out. • When you finish – turn it in and Read Pg. 27-31 in your green book. • Complete the Discovering Density Worksheet.

29. Convection in water • Part 2

30. Heat transfer review • Light is one type of radiation we get from the Sun. • Radiant energy travels through space as waves. • Visible light, ultraviolet, and infrared radiation are responsible for most of the heating of Earth’s surface. • When the Sun’s radiant energy hits Earth’s surface, some of it is absorbed. Molecular motion of the material increases. Molecular motion is heat.

31. continued • Heat can transfer from one material to another when they come in to contact. • The atmosphere is heated by conduction when air molecules contact Earth’s surface, and by reradiation from Earth’s surface. • Heat transfers from warmer to a cooler area or material. • So what about heat in solids and liquids?

32. Heat in solids • In solids, the atoms or molecules are pretty much locked into positions in relationship to one another. When a radiant energy is absorbed by one area in a solid, the molecules begin to vibrate more. The vibration impacts neighboring molecules, and the motion spreads. That’s how heat is conducted through a solid material – by vibrational energy, one molecule to the next.

33. Heat in liquids • In fluids, both liquids and gases, molecules are not locked into position with respect to one another. They can move toward, away from and past one another. • Heat can transfer from one place to another in liquid or gas by conduction, molecules hitting one another – and by absorption of radiant energy. • There’s another way, however, that energy moves in fluids. That’s what we will observe today.

34. Water Inquiry • We figured out how to make layers with salt water solutions. Today is a new challenge. Layer water – with different temperatures. • Lab Worksheet 27 – Layering Hot and Cold Water. • You are going to predict and record how to layer different water temperatures,

35. General Directions • Fill a vial about ¾ full with room-temperature water. I have that set out in jugs so we are all using the same temperature. • Use the bulb pipettes and colored water to create three layers in the vial, red, blue, and clear. • Red is dang hot and blue is the water on ice. • Go to the water station to get water as you need it. Use the small vials for the red hot water and cold blue water. • Keep each vial in its own styrofoam cup to maintain the temperatures.

36. Continued… • Your third vial will be your experimental vial. Fill it about ¾ full with the room temperature water. Create your own layers inside the experimental vial. • Helps

37. Helpful hints • Use the clear plastic cup for failed layering attempts. • A piece of white paper held behind the experimental vial will make it easier to see layers. • Don’t jostle, move, bump, breathe on or even touch a layering experiment in progress. • After refilling the experimental vial with room-temperature water, wait a full minute for the water to become still before adding colored water. • Add old blue water to the chilled water, or red water back to the hot water if you can.

38. Howdja do? • Write how you accomplished your temperature layering in your journal. • Include these if you didn’t already write them. • Wait for the room-temperature water to stop moving. • Use a pipette to carefully introduce blue water under the room temperature water. • Use the other pipette to place hot water on top of the room-temperature water.

39. What Happens Next? • Predict what will happen if your let your layered vial sit for five minutes or more… • Watch • Write down what happens – explain why that happens. • Complete Density WS for tomorrow.