Experiment 1: Slime Time

Inks can be polar or non-polar. Polar solvents pick up polar inks, while non-polar solvents pick up non-polar inks. In this experiment, you will use inks to identify slime and silly putty as polar or non-polar. You will also use paper chromatography to verify the inks are correctly identified as polar or non-polar.

Procedure:

Part 1: Making Slime

1. Weigh out 0.5 g of guar gum into a 250 mL beaker.
2. Measure 50.0 mL of distilled water into a 100 mL graduated cylinder and pour it into the 250 mL beaker that contains the guar gum.
3. Rapidly stir the mixture with a wooden stir stick for three minutes, or until the guar gum is dissolved.
4. Measure 4.00 mL of a 4% Borax solution into a 10 mL graduated cylinder and add it to the guar gum and water.
5. Stir the solution until it becomes slime. This will take a few minutes. If the slime remains too runny, add an additional 1.0 mL of the 4.0% Borax solution and continue to stir until the slime is the slightly runny or gooey.
6. Once you are satisfied with the slime, pour it into your hands. Be sure not to drop any of it on to the floor.
7. Manipulate the slime in your hands. Write down observations made about how slime pours, stretches, breaks, etc. in Part 1 of the Data section.CAUTION: Slime is slippery and if dropped it can make the work area slick.
8. Place the slime back into the beaker and WASH YOUR HANDS.

Part 2: Slime and Putty Ink Tests

1. On a piece of notebook paper make one 20 – 25 mm long mark of each of the inks you are testing (permanent marker, highlighter, Dry Erase, and Uni-ball® Roller Pen). Space the marks at least one inch apart. Use a pencil to label each mark with its description.
   1. Water soluble inks include those in highlighters and certain pens.
   2. Water insoluble inks include those in a permanent pen/markers, newsprint, and a dry-erase markers.
2. While the inks are drying, select a passage or a picture in the newspaper to test with the slime.
3. Develop a hypothesis stating whether or not you believe the slime produced in Part 1 will pick up newsprint ink. Record this hypothesis in the Post-Lab Questions section. Then, break off a small piece of slime that is 3 – 5 cm in diameter. Gently place this piece on top of the newspaper print, then carefully pick it up again.
4. Observe and record in Table 1 whether or not the ink was picked up onto the slime.
5. Break off another small piece of slime. Once the inks from Step 1 have dried gently place the slime on top of the first spot on the notebook paper, then carefully pick it up. Repeat this for each of the inks. Observe and record which inks were picked up (dissolved) by the slime in Table 1.
6. Repeat this ink testing two more times for accuracy.

Hypothesize which inks the silly putty will pick up in the Part 2 of the Data section. Then, perform the ink tests with the Silly Putty® according to the procedure outlined in Steps 3 – 6. Record results in Table 2.

Part 3: Chromatography of Ink Samples

1. Use a pencil or scissors to poke a small hole in the center of a piece of filter paper (see Figure 7).
2. Spot the filter paper evenly spaced approximately 2 cm from the small hole with the two insoluble inks and the two soluble inks that were used in Part 2, Step 1.
3. Obtain a ½ piece of filter paper. Fold the paper in half several times so that it makes a narrow wick.
4. Insert the wick into the hole of the spotted paper so that it is above the top of the filter paper by approximately 2 cm.
5. Fill a 250 mL beaker ¾ full with water.
6. Set the filter paper on top of the beaker so that the bottom of the wick is in the water. The paper should hang over the edge of the beaker with the spotted side up.
7. Allow water to travel until it is approximately 1 cm from the edge of the filter paper. Remove the filter paper from the beaker.
8. Observe which inks moved from where they were originally spotted. Record your observations in Part 3 of the Data section.

Data

Part 1

• Slime Observations:

Part 2

• Hypothesis for Silly Putty® (Procedure Part 2, Step 7):

Part 3

• Observations of inks following chromatography:

Post-Lab Questions

1. Record your hypothesis regarding the slime’s ability to pick up newsprint ink here.
2. Did the slime pick up water soluble or water insoluble inks? From these results, what can you conclude about the polarity of slime molecules?
3. Explain how you determined your hypothesis about whether or not silly putty would pick up water soluble inks. Was your hypothesis correct?
4. Were the inks you used properly classified as soluble and insoluble? Explain your answer.