Polar vs. Non-polar Lab
Chemistry
VS.
Objective:
Part I: Determine the polarity of some common substances.
Part II: Use the polarity of water to separate “inks”.
Materials: water, Vegetable oil, 3 Q-tips, 1 Crayon, 1 washable marker, 1 permanent marker, 1
piece of filter paper, 250-mL beaker, ruler
Part I: “Like Dissolves Like”
Procedure:
1. In your data table:
a. Using a Crayon, color in the two squares in the Crayon column that is also in the
“testing” rows (the squares with the squiggly border).
b. Using a washable marker, color in the two squares in the washable marker column
that is also in the “testing” rows (the squares with the squiggly border).
c. Repeat the coloring using a permanent marker.
2. Dip a Q-tip in water and then rub it over the first square. Record your observations in the
“observation” square below.
3. Use another Q-tip (or the opposite end) and repeat for the other two “water testing”
squares; record observations in the squares below.
4. Dip another Q-tip (or the opposite end) into paint thinner and then rub it over the first
“Vegetable oil testing” square. Repeat the procedure for the final two squares.
Part II: Paper Chromatography
Background
Chromatography is a method used to separate substances in a mixture. It is based upon the
differences in the polarity of solutes dissolved in a particular solvent.
Procedure:
1. Read the entire procedure so that you know what you are doing before wetting your filter
paper.
2. Obtain a piece of chromatography paper (filter paper) and cut into a 2inch wide strip.
3. Make a dot 2 cm from the bottom of the strip.
4. Fill the beaker 1-cm high with tap water.
5. Place the chromatography paper in the beaker so that the bottom is in the water, touching
the bottom. Fold the remaining paper over a stir rod. Place the stir rod on top of the
beaker. Make sure the paper isn’t touching the sides of the beaker.
6. Observe what happens when the water is absorbed up the paper. When the waterline is
about 0.5 cm from the stir rod, carefully remove the paper from the water and set it on the
desk to dry.
Post-Lab Questions: Answer the following in complete sentences.
1. What is the chemical definition of a polar molecule?
2. Draw a water molecule and label the positive and negative sides.
3. In what type of solvent will a polar solute dissolve? In what type of solvent will a
nonpolar solute dissolve?
4. A Crayon is a (polar / non-polar) substance because…
5. Washable marker “ink” is a (polar / non-polar) substance because…
6. Permanent marker “ink” is…because…
7. Suggest 2 other common substances to test with water and paint thinner to determine
their polarity. Based on your knowledge of these substances, predict their polarity.
8. Explain, in terms of the properties of water:
a. Why water moved up the filter paper,
b. Why washable marker “ink” moved up the filter paper with the water, and
c. Why some ink colors moved different distances than others.
9. Based on your results from Part I, how could the chromatography experiment be adapted
for use with a crayon?
Part I- Data:
Solvent
Crayon
Washable Marker
Water testing
Water
observations
Vegetable Oil
testing
Vegetable Oil
observations
Part II- Chromatography paper (attached)
Permanent Marker