Activity 1: Surface Tension
Drops of water on a penny will create a "bubble" effect before breaking and spilling over the sides due to the bonds between molecules at the surface of the water. (see image to left)
However, trying the same thing with soapy water will not have the same results. Soap breaks down bonds between many types of molecules, and water is not able to create surface tension when soap is added.
On your data sheet:
a. In 2-3 sentences, compare the two trials.
b. What was different about the trials?
c. Explain what happened to the surface tension of water when the soap was added.
d. What force acted on the plain water to finally break the surface tension?
However, trying the same thing with soapy water will not have the same results. Soap breaks down bonds between many types of molecules, and water is not able to create surface tension when soap is added.
On your data sheet:
a. In 2-3 sentences, compare the two trials.
b. What was different about the trials?
c. Explain what happened to the surface tension of water when the soap was added.
d. What force acted on the plain water to finally break the surface tension?
Activity 2: Capillary Action
If a paper towel is placed in water, the water will very quickly spread through the paper towel in any direction, including up- away from gravity.
If a paper towel is placed in oil, the oil will spread through the paper towel much, much more slowly- in fact, you can barely see any movement of the oil in a short period of time.
As seen in the image above, paper towels placed between different colors of water will transport water from one cup to the next, blending colors.
On your data sheet:
a. Sketch and label your observation of EACH scenario above (plain water, oil, and colored water)
b. Compare the movement of the water through the paper towel to the movement of the oil.
c. Oil does not adhere to other substances as well as water does. How might this influence oil's ability to move through the paper towel?
If a paper towel is placed in oil, the oil will spread through the paper towel much, much more slowly- in fact, you can barely see any movement of the oil in a short period of time.
As seen in the image above, paper towels placed between different colors of water will transport water from one cup to the next, blending colors.
On your data sheet:
a. Sketch and label your observation of EACH scenario above (plain water, oil, and colored water)
b. Compare the movement of the water through the paper towel to the movement of the oil.
c. Oil does not adhere to other substances as well as water does. How might this influence oil's ability to move through the paper towel?
Activity 3: Cohesion + Adhesion
Part 1: Cohesion
A droplet of water placed on wax paper will slide easily around the surface without breaking apart. If it is broken, moving the smaller drops together will cause them to come back together forming a single drop. The drop is mostly spherical and stays together as it moves.
On your data sheet:
a. Record your observations of the water drop in detail. Describe the shape of the drop as it moves and tell if it moves as one large drop or if it naturally breaks into smaller pieces.
b. Explain how this demonstrates the cohesive property of water.
Part II. Adhesion
Drops of water placed on a laminated card will make it slightly more difficult to slide the cards against each other. You can press the two cards together and let go of one, but it will stay in place, "sticking" to the other card without you having to hold it.
On your data sheet:
a. Describe your observations in detail.
b. Explain how this demonstrates the adhesive property of water.
A droplet of water placed on wax paper will slide easily around the surface without breaking apart. If it is broken, moving the smaller drops together will cause them to come back together forming a single drop. The drop is mostly spherical and stays together as it moves.
On your data sheet:
a. Record your observations of the water drop in detail. Describe the shape of the drop as it moves and tell if it moves as one large drop or if it naturally breaks into smaller pieces.
b. Explain how this demonstrates the cohesive property of water.
Part II. Adhesion
Drops of water placed on a laminated card will make it slightly more difficult to slide the cards against each other. You can press the two cards together and let go of one, but it will stay in place, "sticking" to the other card without you having to hold it.
On your data sheet:
a. Describe your observations in detail.
b. Explain how this demonstrates the adhesive property of water.
Activity 4: Solubility/Universal Solvent
Consider the following data:
Salt will dissolve in water.
Sugar will dissolve in water.
Oil will NOT dissolve in water.
Sugar will NOT dissolve in oil.
Salt will NOT dissolve in oil.
On your data sheet:
a. Record your observations of each scenario.
b. Water is the universal solvent in part because of its polarity. Oil, however, is not a polar substance. Given this information, explain on your data sheet why you think the oil did not dissolve in the water. Be specific.
Salt will dissolve in water.
Sugar will dissolve in water.
Oil will NOT dissolve in water.
Sugar will NOT dissolve in oil.
Salt will NOT dissolve in oil.
On your data sheet:
a. Record your observations of each scenario.
b. Water is the universal solvent in part because of its polarity. Oil, however, is not a polar substance. Given this information, explain on your data sheet why you think the oil did not dissolve in the water. Be specific.
Activity 5: Density
a. Sketch and label the density column.
b. Write the density of each liquid beside its name on your diagram.
c. What do you notice about liquids whose densities are less than that of water?
d. What do you notice about the order of the liquids (in relation to their densities)? Where are the liquids with the greatest densities?
^^ Density Colum ^^
Light yellow, bottom: Corn Syrup
Blue: Water
Clear, pale yellow: Vegetable oil
Green (top): Rubbing alcohol
Densities: (given in grams per cubic centimeter)
Water: 1.00 g/cm3
Rubbing Alcohol: 0.79 g/cm3
Corn Syrup: 1.37 g/cm3
Vegetable Oil: 0.93 g/cm3
Activity 6: Specific Heat
On your lab data sheet, explain what happens in the following video. Why did the second balloon, which has only air inside, pop when placed over the candle but the first balloon, which has water inside, did not?