Q 4. Two experiments are carried out to investigate energy transfer in water. In Experiment 1, cold water is gently heated at the top of a glass boiling tube. A block of ice trapped at the bottom remains solid even when the water at the top begins to boil. In Experiment 2 , cold water is gently heated at the bottom of the tube. Ice at the top of the tube melts before the water boils. a. What is the process through which thermal energy travels through the glass? b. What is the principal process in Experiment 2 which takes the energy from the water at the bottom of the ice at the top? c. Describe how the process in b) occurs? d. Suggest two reasons why the ice in Experiment 1 does not melt, even when the water at the top begins to boil?
Answers
Explanation:
Fill one of the jars with very hot tap water. Add a drop of red food coloring. What happens to the drop? Watch for a minute, then put the red jar into the baking pan.
2Fill the other jar with cold water. Add a drop of blue food coloring. What happens to that drop?
Tips for Home Scientists
This experiment can be tricky--and messy. You may want to practice step 6. Get a grown-up to help.
3Cut about 2 inches off one short side of the index card. You should end up with a square about 3 inches on a side.
4Slowly add more water to the blue jar until you can see a bulge of water over the rim of the jar.
Add water till you see the bulge
6This part is very tricky. You may want to practice it a few times over the sink with a jar of plain water. Pick up the blue jar and turn it straight upside-down. You don't need to put your hand on the card. The water will hold the card in place. (Just flip the jar over. Don't hesitate. If the jar is tilted but not turned over completely, the water will gush out and make a mess.)
Removing the card
Lay the card on top 5Lay the square card carefully onto the top of the blue jar. Tap the card gently with your finger. (Don't poke it. You want the card to be flat and form a seal with the water and the jar.)
Flip the jar over
7Put the upside-down blue jar right on top of the red jar.
8Have someone hold onto both jars while you very slowly and carefully pull the card out.
9What happens? What color is the water in the top jar? What color is the water in the bottom jar?
10Empty both jars. Rinse them. Repeat steps 1 through 6--but put the jar with the blue-colored cold water in the baking pan and put the card on top of the jar with the red-colored hot water. Turn the red jar upside-down and put it on top of the blue jar.
Slowly pull out the index card. What happens? What color is the water in the top jar? What color is the water in the bottom jar?