After reviewing my peers work there was a mix of the hypothesis that said the cold water would freeze faster. Others like myself said that hot water would freeze faster. We also took similar approaches to how experiermnts were done. I saw many people would sue a freezer over leaving the cup outside. Many of us also used faucet water from varying temperatures for our water variables.
Overall it was divided on if hot or cold water froze faster. Many used the mpemba effect to justify their hypothesis and create theories. Many of us made hypothesis that cold water froze faster. An example is Angela Hanson's hypothesis "I immediately came to a hypothesis that cold water has to freeze faster than hot water, it just made sense with the temperatures being so low from already in cold water."
We used a mix of personal experience, background knowledge, and some research to make our hypothesis. We could use them all to compare experiments and ideas. I saw a mix of results of which froze faster but after looking up information and finding an article on medium.com ( https://medium.com/the-physics-arxiv-blog/why-hot-water-freezes-faster-than-cold-physicists-solve-the-mpemba-effect-d8a2f611e853) It is found that hot water freezes faster than cool water more often. But it is not fully concrete and conclusive. Maybe future chemistry students will find the answer.
Monday, January 21, 2019
My own teacher activity. Acids and bases basics
pH in Our Lives
(This was my activity that I made based on the PHET simulations)
Many foods and items in our lives are acids and bases. We will be exploring Phet simulations to see these objects and how we can change them on the pH scale.
(This lesson is made for third through fifth grade)
SCI.CC2.3-5 Students routinely identify and test causal relationships and use these relationships to explain change. They understand events that occur together with regularity may or may not signify a cause and effect relationship.
SCI.CC6.3-5 Students understand different materials have different substructures, which can sometimes be observed; and substructures have shapes and parts that serve functions.
SCI.SEP1.A.3-5 Students ask questions that specify qualitative relationships. This includes the following: Ask questions about what would happen if a variable is changed. Identify scientific (testable) and non-scientific (non-testable) questions. Ask questions that can be investigated and predict reasonable outcomes based on patterns such as cause and effect relationships.
1. Draw the pH scale and label it with where acids bases and neutrals are. (we will use this chart during our simulation). Color in the scale using the simulation scale colors.
2. Use the pH Scale Basics simulator and fill the container with each of the liquids and measure their pH. Record the information on the scale and in the charts below. One chart is for acids and one is for bases.
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Substance
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pH
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Acid or base
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Substance
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pH
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Acid or base
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3. Order the substances on the chart according to the scale most acidic to least acidic.
4. From what you have seen on the chart what makes something an acid and what makes something a neutral?
5. How can you change the pH of a substance?
6. What does it mean to dilute something? What substance can be used to dilute substances?
7. Using the chart below write the pH of 6 substances and one mystery substance. Then find the amount of water it takes to dilute the substance until the container is full. Put .06 liters of each substance in for an accurate reading
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substance
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pH
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pH after dilution
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soda
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2.50
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Hand soap
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10
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Chicken soup
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5.80
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blood
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7.40
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Drain cleaner
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13.0
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Orange juice
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3.50
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Mystery object
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7.40
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8. What was the mystery object?
9. What do the acids and bases have in common?
10. Combine two substances together and record their pH. It will work better if you combine an acid and base. What was the result?
11. As stated at the start of the lesson these objects are found all around the home? Look up more acids and bases that can be found in your home.
Balloon and Static electricity Teacher activity (activity 8 question 1)
PHet Electricity Simulations Analysis Worksheet
Name: Leah
Balloons and Static Electricity
to the website: https://phet.colorado.edu/en/simulation/balloons-and-static-electricity and click on the “Play” symbol to open the simulation.
1. Count the number of positive and negative charges on each object in the simulation and determine the overall charge of each object.
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+ Charges
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- Charges
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Overall Charge
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Sweater
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57
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57
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0
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Balloon
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4
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4
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0
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Wall
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52
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52
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0
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2. Click on the balloon and drag it over and rub the balloon against the wall. Describe what, if anything, happens to the balloon/wall. Pull the balloon slightly away from the wall and release it, does anything happen?
When rubbed against the wall nothing happened. When pulled away from the wall and released nothing changed with the balloon.
3. Now drag the balloon over the sweater and rub it against the sweater. Describe what, if anything, happens to the balloon/sweater.
All of the negative charges moved to the balloon and the balloon stuck to the sweater
4. Count the number of positive and negative charges on each object in the simulation and determine the overall charge. (It might be easier to select “show charge differences” and count how the charges have changed and use your numbers above to answer.)
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+ Charges
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- Charges
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Overall Charge
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Sweater
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57
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0
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positve
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Balloon
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4
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57
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negative
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Wall
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0
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0
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No charge
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5. Pull the balloon back toward the middle of the simulation and let it go, describe what happens? How can you explain this occurrence?
The balloon moves back to the sweater. This happens because the balloon is negatively charged and the sweater is positively charged. Opposites attract each other.
6. Drag the balloon over to the wall. As you bring the balloon near the wall, what happens within the wall? Why do you think this happens?
The balloon sticks to the wall but all negative charges move away. The negative charges are trying to balance out to the wall and do not require extra charges.
7. Hold the balloon just away from the wall and release it. What happens? Why do you think this happens?
The balloon moves back to the wall to balance out its charge.
8. Hold the balloon a little further from the wall and release it, keep repeating this moving the balloon a little bit further from the wall each time until the balloon stops being attracted to the wall. What eventually happened? Is the balloon more attracted to the sweater or the wall? Why?
It took less than half the distance for the balloon to return to the sweater because it has such a strong positive charge unlike the wall that has no charge. The balloon is more attracted to the sweater.
Click “Reset Balloon” then click on the picture with two balloons. Lastly click on “remove wall” to remove the wall.
9. Determine the number of positive charges, negative charges and the overall charge of each object. (Sweater number should not have changed.)
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+ Charges
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- Charges
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Overall Charge
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Sweater
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57
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57
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No charge
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Green Balloon
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4
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4
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No charge
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Yellow Balloon
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4
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4
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No charge
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10. Take the green balloon and rub it gently against the sweater. Then determine the new charges.
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+ Charges
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- Charges
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Overall Charge
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Sweater
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57
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49
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postive
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Green Balloon
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4
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12
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negative
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Yellow Balloon
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4
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4
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No charge
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11. Drag the green balloon over to the yellow balloon, does it have any effect on the yellow balloon? Why or why not?
It has no effect to the yellow balloon because the yellow balloon has no charge
12. Release the green balloon, what happens? Why?
The green balloon moves to the sweater because it has a positive charge
13. Now drag the yellow balloon and rub it against the sweater. Determine the new charges.
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+ Charges
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- Charges
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Overall Charge
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Sweater
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57
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39
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postive
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Green Balloon
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4
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12
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negative
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Yellow Balloon
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4
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14
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negative
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14. Pull the green balloon off the sweater and put it all the way across the room. Quickly grab the yellow balloon and bring it near the green balloon? What happens when the balloons are brought together? Why does this happen?
The green balloon moves away from the yellow balloon and quickly moves back to the sweater. The yellow balloon sinks down and moves back to the sweater. Both are negatively charge and will not attract one another. When brought together they move apart.
15. Try to find a way to get the 2 balloons to stick to each other.
Both will stick together when they are placed on the sweater next to eachother
16. What would you need to do in order to get the balloons to stick together? After completing this activity is it possible to do that? Why or why not?
You would need more positive charges on one balloon to have them stick together. With this simulation it is not possible to do that.
Analysis
17. When an object becomes charged which charge is transferred between the objects?
Positive and negative ions
18. How does an object become positively charged?
All the negative or most are removed
19. How does an object become negatively charged?
All the positive ions or most are removed
20. In order to repel each other two objects must have the same charge(s).
21. In order to attract each other two objects must have opposite charge(s).
22. When the balloon was brought near the wall, the wall technically stayed neutral, but the balloon was still attracted to the wall. How can this be explained?
The balloon was attracting the positive ions but the wall was not completely positive.
Part B: John Travoltage!
Go to the following: http://phet.colorado.edu/en/simulation/john-travoltage and click Play! (sound on makes it more fun!)
1) Click on John Travoltage’s arm and move his finger by the doorknob. What happens?
Nothing happens
2) Move his finger away from the doorknob and rub John Travoltage’s FOOT across the carpet. Describe what happens!
Negative ions move up his foot and to his finger.
3) Move his finger toward the doorknob again. Describe what happens this time. Why does that happen?
He is shocked. The positive charge from the doorknob has extra ions that want to move to his hand and it shocks him.
4) Move his finger away again and drag his foot across the carpet multiple times. Then bring his hand toward the doorknob again. What do you notice about the distance between his finger and the doorknob this time compared to the first time? Why do you think its changed.
His hand is further away but the shock gets longer. He is still shocked because the number of negative ions increased greatly and still want to “jump” to the source.
5) Before John Travoltage approaches the doorknob is the doorknob charged or neutral? What evidence do you have to support your claim?
The door knob is positively charged because it is made of metal. Metal is postivly charged.
6) a) Why does carpet tend to produce differences in static electricity more than hardwood or tile floors (think!)?
The carpet is not as smooth and can build up negative charges from movement.
b) Why do you sometimes feel a shock when you touch metallic objects (like the doorknob)?
Metal is positively charged and we collect more negative ions.
7) Why doesn’t John Travoltage get a shock if he touches the doorknob without rubbing his foot on the carpet?
He is neutrally charged
8) Charge John Travoltage up a lot and observe which direction the spark travels when John Travoltage’s finger comes close to the metal doorknob.
a) Draw a diagram of his finger and the doorknob below.
b) Label the CHARGES (positive, negative, neutral) of both objects and show the direction the spark is traveling!
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