Condensation: Puddle Trouble

We have spent the last couple of days reading about water.  We learned about water on earth and that it cycles through three states, or phases:  solid, liquid, and gas.

When the students came in after lunch,  I was talking to the students as I shuffled with papers until I announced, "What's with the puddle?" (phenomenon)  to my desk, which had my cup of iced tea from lunch.  Around it was a puddle of water that had soaked the surrounding papers - one of which I was sending to the office!  "Where did all this water come from?"

What's With the Puddle?

Students shared their claims...

How can we test your claim.  Remember you have to have data to support your claim.

Take out your science journal. Our problem, where did the water around the cup come from?

  

I showed students that another cup from the morning was not puddling.  They noticed that it did not contain ice. 

Students discussed in groups how they could design a test to determine where the water came from.  

Then based on that, they began to make "I think" statements (predictions).  from inside the cup, from the ice, from the air, were some of their responses.

The experiment: (from one group)

Claim: the water came from inside the cup and evaporated to the surrounding air, and condensed on the cup.

materials:

2 plastic cups

250 mL water

food coloring

ice

2 thermometers

saran wrap

1.  Set up 2 cups.  1a.  Take temperature of water

2.  Put 100mL  ice in one cup.  

3.  Pour 100mL water over ice to top line below rim.  

4.  Fill 2nd cup to same amount - 100mL water.  4a. we need to see the water, so we will add 5 drops of food coloring.

4b.  We need to measure if the water level lowers (because it will evaporate) so we will mark with a sharpie starting level.

5. wait 10 minutes

collect data - What type of measurable data can we collect?  temperature, amount of water in cup (mark water level, with sharpie, mark again after amount of time, measure any change between the marks), amount of condensation (any water outside cup by using a grid system.  Draw the side of the cup on graph paper and mark the amount of droplets - count the squares). 

6.  make observations

Students recorded their data by making drawings and writing noticings.

Results:  We noticed that in the cup without ice, nothing happened.  The temperature stayed the same.  The water level stayed the same.  The level of the water stayed the same.

The cup with ice, changed.  The temperature decreased.  The water level was higher.  The water was lighter in color.  There was a fog above the ice and on the outside of the cup.  There were droplets of water on the outside of the cup.

We discussed our results and looked up some information in our books, then wrote our conclusion.

Conclusion: We claim that the water on the cup came from the air around us.  It did not come from inside the cup (through the cup), because the water was clear, not red.  The cooler temperature (less heat energy) caused the air to condense on the cup.  This is similar to what happens in the atmosphere as a cloud.  Also, on the grass in the morning as dew.

New questions:  Did the water inside the cup evaporate into the air?  Would we have the same result at night as during the day?  What is the temperature difference where condensation occurs? (inside water/outside air).  What if the air was cold and the cup was hot?

Next steps:  Develop a test to retest making only one change (variable).  

One group - We would like to test the cup with a zip bag around it to prevent air from getting on the cup.  We believe that there would not be condensation.

(Same amount of water, same temperature air, same amount ice)

Revisit - Engineering connection:  We decided that we should develop a device to prevent this from happening. The kids thought of a few that already exist - insulator, double cup, and tested which worked best.  They compared it to the plastic bag around the cup.  We found out that they all worked because it works as a barrier keeping the cold temperature of the cup away from condensing with the water vapor.
Design a new product to prevent the puddle on the paper.  Identify the problem as 1. Prevent condensation from forming on the outside of the cup.  or 2. Prevent the condensation from dribbling to the paper.  Interesting how creative they are!

Here is a great link for reading 
http://www.ck12.org/physical-science/Condensation-in-Physical-Science/#all