Lab 8: Chemical Reactions I Pre-lab Questions 1. Name the chemical that makes up teeth. 2. How does plaque harm teeth? 3. How does fluoride promote dental health? 4. Write two solubility rules that are used in this lab. Experiment: Battle of the Mouth Rinses Some mouth rinses contain fluoride, usually in the form of sodium fluoride, which is soluble in water. In this lab, you will determine which one of two mouth rinses would be better at preventing cavities by replacing lost minerals with fluoride. You will do this by determining which rinse contains fluoride. Procedure **Take photographs of your experiment set up and your results. Submit them with your laboratory report.** 1. Label the two test tubes with a permanent marker as A and B. HINT: Make sure to write down which rinse is A and which is B. 2. Pour 10 mL of Rinse A into the test tube marked A. 3. Pour 10 mL of Rinse B into the test tube marked B. HINT: If using the same graduated cylinder to measure your rinses, wash the cylinders WELL between pours to prevent cross-contamination. 4. Pour 3 mL of 1 M Ca(C2H3O2)2 solution into each of the test tubes. Gently stir each test tube with a stir rod to mix. Be sure to clean your stir rod each time before placing it in a solution. CAUTION: Mixing should be done gently to prevent glass breakage and injury. 5. Observe and record initial observations immediately after adding calcium acetate to the test tubes. 6. Observe the reactions for at least 10 minutes to ensure it is finished. HINT: A positive test is indicated by a cloudy appearance of the solution. The precipitate formed can be more easily seen if the test tube is held up to the light. The precipitate will eventually settle to the bottom of the test tube. 7. Let the test tubes sit for an hour. After an hour, record final observations. 8. Record all observations in the Data section. 9. To clean up, you can rinse the small amount of precipitate down the drain. Data · Observations of NaF and Ca(C2H3O2)2 (see sequence of pictures below) · Observations of Rinse A and Ca(C2H3O2)2 · Observations of Rinse B and Ca(C2H3O2)2 Post-lab Questions 1. Take photographs of your experiment set up and your results. Submit them with your laboratory report. 2. Did either of the mouth rinses contain fluoride? How did you know? 3. Which mouth rinse would be better at fighting cavities? Why? 4. Based on the solubility rules learned in this lab, could you use potassium nitrate to test for fluoride in mouth rinses? Explain your answer. ©eScience Labs, 2013 Lab 7: Polar Bonding Pre-lab Questions 1. What two conditions are considered when determining whether a molecule is polar or non-polar? 2. What determines if a bond is polar? 3. List several examples of polar molecules. 4. List several examples of non-polar molecules. 5. What is the rule when using polar and non-polar solvents? Experiment: Slime Time Some inks are polar while others are non‐polar. A ...

1. Lab 8: Chemical Reactions I
Pre-lab Questions
1. Name the chemical that makes up teeth.
2. How does plaque harm teeth?
3. How does fluoride promote dental health?
4. Write two solubility rules that are used in this lab.
Experiment: Battle of the Mouth Rinses
Some mouth rinses contain fluoride, usually in the form of
sodium fluoride, which is soluble in water. In this lab, you will
determine which one of two mouth rinses would be better at
preventing cavities by replacing lost minerals with fluoride.
You will do this by determining which rinse contains fluoride.
Procedure
**Take photographs of your experiment set up and your results.
Submit them with your laboratory report.**
1. Label the two test tubes with a permanent marker as A and B.
HINT: Make sure to write down which rinse is A and which is

2. B.
2. Pour 10 mL of Rinse A into the test tube marked A.
3. Pour 10 mL of Rinse B into the test tube marked B.
HINT: If using the same graduated cylinder to measure your
rinses, wash the cylinders WELL between pours to prevent
cross-contamination.
4. Pour 3 mL of 1 M Ca(C2H3O2)2 solution into each of the test
tubes. Gently stir each test tube with a stir rod to mix. Be sure
to clean your stir rod each time before placing it in a solution.
CAUTION: Mixing should be done gently to prevent glass
breakage and injury.
5. Observe and record initial observations immediately after
adding calcium acetate to the test tubes.
6. Observe the reactions for at least 10 minutes to ensure it is
finished. HINT: A positive test is indicated by a cloudy
appearance of the solution. The precipitate formed can be more
easily seen if the test tube is held up to the light. The
precipitate will eventually settle to the bottom of the test tube.
7. Let the test tubes sit for an hour. After an hour, record final
observations.
8. Record all observations in the Data section.
9. To clean up, you can rinse the small amount of precipitate
down the drain.
Data
· Observations of NaF and Ca(C2H3O2)2 (see sequence of
pictures below)
· Observations of Rinse A and Ca(C2H3O2)2

3. · Observations of Rinse B and Ca(C2H3O2)2
Post-lab Questions
1. Take photographs of your experiment set up and your results.
Submit them with your laboratory report.
2. Did either of the mouth rinses contain fluoride? How did you
know?
3. Which mouth rinse would be better at fighting cavities?
Why?
4. Based on the solubility rules learned in this lab, could you
use potassium nitrate to test for fluoride in mouth rinses?
Explain your answer.
©eScience Labs, 2013
Lab 7: Polar Bonding
Pre-lab Questions
1. What two conditions are considered when determining
whether a molecule is polar or non-polar?
2. What determines if a bond is polar?

4. 3. List several examples of polar molecules.
4. List several examples of non-polar molecules.
5. What is the rule when using polar and non-polar solvents?
Experiment: Slime Time
Some inks are polar while others are non‐polar. A polar solvent
will pick up polar inks, while a non‐polar solvent will pick up
non‐polar inks. In this lab 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
**Take photographs of your experiment for Parts 1, 2, and 3;
and your results. Submit them with your laboratory report.**
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 stirring rod for at least 3
minutes and until the guar gum is dissolved.

5. 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 right consistency.
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.
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. Space the marks at least one
inch apart. Use a pencil to label each mark with its description.
a. Water soluble inks include those in highlighters and certain
pens.
b. Water insoluble inks include those in permanent
pens/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. Break off a small piece of slime that is 3 - 5 cm in diameter.
Gently place this piece on top of the newspaper print, and 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, and 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.

6. 7. Before performing ink tests on silly putty, in the Data
section, hypothesize which inks the silly putty will pick up.
8. Perform ink tests on silly putty in the same manner as above.
Record your 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 4).
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.
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 3/4 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:

7. Part 2
Table 1: Results of Ink Testing for Slime
Name of Ink
Picked up (dissolved)
Did not pick up
Test 1
Test 2
Test 3
Test 1
Test 2
Test 3
Newsprint
Highlighter
Roller ball pen

8. Sharpie marker
Dry-erase marker
· Hypothesis for Silly Putty (Procedure Part 2, Step 7):
Table 2: Results of Ink Testing for Silly Putty
Name of Ink
Picked up (dissolved)
Did not pick up
Test 1
Test 2
Test 3
Test 1
Test 2
Test 3
Newsprint

9. Highlighter
Roller ball pen
Sharpie marker
Dry-erase marker
Part 3
· Observations of inks following chromatography:

10. Post-lab Questions
1. Take photographs of your experimental set up for Parts 1, 2,
and 3 and your results. Submit them with your laboratory
report.
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. Was your hypothesis
correct?
4. Were the inks you used properly classified as soluble and
insoluble? Use evidence from your results to explain your
answer.
© eScience Labs, 2013