Red Hot Knife vs Ice

Introduction

Today you are going to see what happens when hot meets cold!

Last week you learned how to calculate the energy it takes to change the temperature of something.

Don't forget that any time sometime changes states/phases it also takes a lot of energy!

What do we call the hidden energy it takes to boil a substance
LIQUID ←→ GAS (Vapour)
The of CHOOSE magic phase change fusion states evaporization vaporization freezing condensation

 

What do we call the hidden energy it takes to melt a substance
LIQUID ←→ SOLID
The of CHOOSE magic phase change fusion states evaporization vaporization freezing condensation

 

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1) Hot Water vs Cold Water

1. Eye Protection On
2. Measure 50g of cold water
3. Measure 50g of hot water
4. Measure the initial Temperature of cold water: °C
5. Measure the initial Temperature of hot water: °C
6. Predict the Temperature of mixed water: °C
7. Predict the "winner": CHOOSE Hot Water Tie (within 10°) Cold Water
8. Pour them both into a cup
9. Mix with the themometer for a minute
10. Measure the final Temperature of mixed water: °C

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ΔT = T_final - T_initial
+ Positive = Temperature went up (Gained Heat)
- Negative = Temperature went down (Lost Heat)

How much did the temperature of the cold water change?
ΔT_cold = °C

How much did the temperature of the hot water change?
ΔT_hot = °C

 

Which was the "winner": CHOOSE Hot Water Tie (within 10°) Cold Water

What is your theory for why that happened?
Told Mr Dash your theory CHOOSE Yes No

 

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2) Hot Water vs Ice

1. Eye Protection On
2. Measure 50g of ice
3. Measure 50g of hot water
4. Measure the initial Temperature of ice: °C
5. Measure the initial Temperature of hot water: °C
6. Predict the Temperature of mixed water: °C
7. Predict the "winner": CHOOSE Hot Water Tie (within 10°) Ice
8. Mix them both in a cup
9. Mix with the themometer until all ice has melted
10. Measure the final Temperature of mixed water: °C

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ΔT = T_final - T_initial
+ Positive = Temperature went up (Gained Heat)
- Negative = Temperature went down (Lost Heat)

 

How much did the temperature of the ice change?
ΔT_ice = °C

How much did the temperature of the hot water change?
ΔT_hot = °C

 

Which was the "winner": CHOOSE Hot Water Tie (within 10°) Ice

What is your theory for why that happened?
Told Mr Dash your theory CHOOSE Yes No

 

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3) Hot Metal vs Water

1. Eye Protection On
2. Get a 10¢ coin
3. Measure the mass of the coin g
4. Measure 10g of cold water (from the fridge) into a small cup
5. Measure the initial Temperature of cold water: °C
6. Temperature of red hot metal: 825C
7. Predict the Temperature of water: °C
8. Predict the "winner": CHOOSE Hot Metal Tie (within 10°) Cold Water
9. Gloves on
10. Ask Mr Dash to help you heat a coin until it is red-hot!
11. Drop the red-hot coin into the cup of water
12. Mix with the themometer until equilibrium is reached
13. Measure the final Temperature of the water: °C

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Which was the "winner": CHOOSE Hot Metal Tie (within 10°) Cold Water

What is your theory for why that happened?
Told Mr Dash your theory CHOOSE Yes No

 

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4) Red Hot Knife vs Ice

1. Eye Protection On
2. Get an ice cube
3. Measure the mass of the ice cube g
4. Temperature of red hot metal: 825°C
5. Predict what percentage of the ice you will be able to melt with the red-hot knife: %
6. Predict the "winner": CHOOSE Hot Knife (metal) Tie (within 10°) Ice
7. Gloves On
8. Ask Mr Dash to help you heat the knife until it is red-hot!
9. Now melt as much of the icecube as possible
   

 

Which was the "winner": CHOOSE Hot Knife (metal) Tie (within 10°) Ice

What is your theory for why that happened?
Told Mr Dash your theory CHOOSE Yes No

 

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Clean-up

1. Empty all water and ice into the sink
2. Remove the coin from the water and return it
3. Return all equipment
4. Remove Eye Protection, place in bag, and place in the container

 

Did you tidy everything? CHOOSE Yes No

 

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