Syllabus Point: Material World

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Focusing on:

• Properties of solids, liquids, gases
• Reversible and irreversible changes to materials
• Properties of materials and their related uses

[AnnabelleBuda]

Material World

• Properties of solids, liquids, gases

• Reversible and irreversible changes

• Air and mass

• Properties and uses

• Reasons and benefits of solid, liquid and gas fuels

Ideas:

• Making bath bombs: baking soda, citric acid, magnesium sulfate (unnecessary), oil

• Hot ice (change of state: provide sodium acetate and vinegar, teacher demonstration)

• Fizzybombs

• Capture carbon dioxide gas in balloons: Where is it coming from?

• Use CO2 as an engine to propel a mini vehicle: Uses from properties of materials/ reactions

• Can look at gas having mass? Weight of solutions before and after reaction.

• Change of state from solid to liquid/gas and irreversible reactions

• Hot ice as a reversible reaction (recrystallisation) Uses/properties of hot ice (pocket hand warmers and bath bombs)

• Modelling particles with analogy: comparing macroscopic and microscopic properties of substances (eg sand, sugar, salt).

• Is sand/ flour a liquid? Properties apply at a molecular level.

Science Analogies

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Method, Equipment and Costing

Practical 1

1. Make bath bombs/ fizzy bombs.
2. Make/ assemble mini gas-powered vehicle.
3. Capture carbon dioxide gas from bath bombs in balloons.
4. Use gas to power mini-vehicle.

Equipment

https://www.scientificamerican.com/article/sudsy-science-creating-homemade-bath-bombs/ https://www.scientificamerican.com/article/build-a-balloon-powered-car/

• Cornstarch (2 tbs) $5/ kg
• Citric acid (1 ⅓ tbs) $3.31/ 100 g
• Sodium bicarbonate (2 ⅔ tbs) $0.36/ 100 g
• Water (1 tsp)
• Vegetable oil (1 tsp) $0.22/ 100 mL
• Food colouring (1-2 drops) $4.02 four pack
• Baking molds/ plastic cups (1) $3-4 20 cups
• X2 bowls for mixing

Amounts for 1 bath bomb.

• Balloons $5.00 hundred pack
• Plastic bottle
• Straws $1.00 hundred pack
• X4 bottle caps
• Tape
• Scissors
• Wooden Skewers $3.00 hundred pack

Method

1. Combine the dry ingredients (cornstarch, citric acid, sodium bicarbonate) for the bath bombs in a bowl and mix well.
2. Combine the wet ingredients together in a separate bowl and mix well.
3. Add the wet ingredients to the dry ingredients slowly and dropwise. Stir the mixture when it fizzes and don’t add too fast. You may not need to add all the wet ingredients!
4. Spoon the mixture into the baking mold, pressing down as you go. Make sure it is pressed down very firmly.
5. Leave the bath bomb to dry overnight/ for a few hours.
6. Make your plastic bottle car.
7. When the bath bomb is dry put it in a cup with a funnel over the top.
8. Attach a balloon to the funnel.
9. Add water to the bath bomb and quickly seal the funnel on top of the cup with parafilm/ tape.
10. Shake it a bit and watch the balloon fill up as the bath bomb dissolves.
11. Pinch the balloon shut before removing it.
12. Keeping the end pinched shut, attach the balloon to the straw on the plastic bottle car.
13. Release the balloon to start the car.

Costing

• Cornstarch (2 tbs) $5/ kg
• Citric acid (1 ⅓ tbs) $3.31/ 100 g
• Sodium bicarbonate (2 ⅔ tbs) $0.36/ 100 g
• Water (1 tsp)
• Vegetable oil (1 tsp) $0.22/ 100 mL
• Food colouring (1-2 drops) $4.02 four pack
• Baking molds/ plastic cups (1) $3-4 20 cups
• X2 bowls for mixing $4.00 twenty pack
• Balloons $5.00 hundred pack
• Plastic bottle
• Straws $1.00 hundred pack
• X4 bottle caps
• Tape
• Scissors
• Wooden Skewers $3.00 hundred pack

Total approximate cost: $40-50 (whole class kit)

• Kitchen scale $12-16 kmart (1 g graduation)

Discussion Questions

• Where does the gas filling the balloons come from?
• Compare the properties of the solid bath bomb, liquid water and the gas captured in the balloon.
• Why does the car move forward when the gas is released?
• Is the dissolving of the bath bomb in the water a reversible or irreversible change? (compare with dissolving salt/sugar in water)

[AnnabelleBuda]

Practical 3

1) Make invisible inks 2) Write spy letters using invisible inks 3) Test methods of revealing invisible inks 4) Reveal the spy letters and identify the ink

Equipment

• Lemon juice/ vinegar
• Laundry detergent (whitening)
• Iodine solution
• White crayons
• Black light
• Heat lamp, iron, candle etc

Method

1. Using the lemon juice, students will compose a short spy letter.
2. Repeat exercise with white crayons on white paper and a dilute solution of laundry detergent.
3. The students will then use trial and error on seperate pieces of paper to test which inks become visible with which solutions. The solutions are iodine solution, black light, watercolour and heat. They should keep a record of how each ink is made visible.
4. The students will then swap spy letters and attempt to make each others letters visible. From the methods they used to make the inks visible, they should be able to identify which ink was used.

Costing

• Lemon juice/ vinegar $1.65/ 500 mL
• Laundry detergent (whitening) $6.00/ 1L
• Iodine solution $15.00/ 60 mL
• White crayons
• Black light $15.00
• Heat lamp, iron, candle etc $2.00

Total approximate cost: $40-50

Discussion Questions

• Which of the methods of revealing the ink are reversible changes, which are irreversible changes?
• How can you tell whether or not they are reversible changes?
• What properties make the substances useful as invisible inks?

[AnnabelleBuda]

Practical 4

• The effect of heat/ cooling on the expansion of water/ other liquids.
• Make a homemade thermometer.
• Link to ocean currents (HSIE: Geography syllabus)

1) Create a homemade thermometer using a small jar, blu-tack and a clear straw. 2) Test the effect of heat on the expansion of water and water with salt. 3) Link the expansion of water to the expansion of the ocean leading to rising sea levels.

Equipment

• Water
• Small (250 mL) bottle
• Food colouring
• Salt
• Thermometer
• Blu-tack
• Clear straws
• Parafilm
• Permanent marker

Method

Complete Student Inquiry sheet.

Part A (Assembling the thermometer): 1) Fill the bottle to the brim with water mixed with a few drops of food dye. 2) Cover carefully with a piece of parafilm (parafin wax) and insert the straw through the parafilm into the water. 3) Make sure the seal around the straw and the neck of the bottle is airtight using more parafilm and/or blu-tack. 4) Blow gently into the straw to test the seal. The water should come up the straw a little when you stop blowing. 5) Set the thermometer on a stable surface and use a permanent marker to mark the level of the water in the straw and room temperature. 6) Attach the pre-made thermometer to your bottle using sticky tape and record the temperature.

Part B (Measuring changes in temperature): 1) Use a hairdryer to warm the bottle. Mark the new height of the water and the reading from the thermometer. 2) Measure the height difference between the original marking and the new marking. Also calculate the difference in temperature from the starting temperature to the new thermometer reading. 3) Allow the thermometer and the bottle to return to room temperature and repeat steps 1 and 2.

Part C (Repeat with salt water): 1) Dissolve 35 g of salt into 1 L of water to simulate ocean salinity. 2) Repeat Part A and Part B using the salt water instead of plain water.

Complete Student Reflection sheet.

Costing

-250 mL bottle $3.00

• Food colouring $4.02 four pack
• Salt $2.26 500 g
• Thermometer $5.00
• Blu-tack $2.50
• Clear straws $1.00 (100 pack)

Total approximate cost: $25- $30

Discussion Questions

• How do your observations relate to what you know about rising sea levels?
• Is the change shown by the water a reversible or irreversible change?
• Why do you think the water undergoes the changes you observed?
• What differences did you see between the salt water and the plain water?
• What other tests could you perform to see the difference in the effect of temperature on salt water and plain water?