Level 3

	Level 3 Lab Activity
Advanced Chemistry I, Chemistry II, and Organic

Objective:

To prepare four polymer elastomers in the laboratory
To examine physical properties of the elastomers
To describe the role of bonding and crosslinking in organic molecules
To compare addition and condensation polymerization.

Applicable Science Concepts:

The terms polymer, elastomer, and crosslinking should be researched prior to this lab, along with the concepts of addition and condensation polymerization.

Materials:

Elmer's® White Glue-All
(30 mL per ball)
Elmer's® Blue Glue Gel
(30 mL per ball)
Borax powder (solid sodium tetraborate decahydrate), Na₂B₄O₇•10H₂O(s)
(1 g per ball)
Liquid latex rubber, from local craft or hobby store
(15 mL per ball)
5% acetic acid solution, CH₃COOH(aq), (household vinegar)
(15 mL per ball)
Saturated sodium silicate solution, Na₂SiO₃(aq)
(12 mL per ball)
50% ethanol solution, C₂H₅OH(aq)
(3 mL per ball)
Small disposable plastic cups
Plastic stirring rod or wooden stick
Tap water
Small sealable plastic bags

Equipment:

Balance
Weighing boats or weighing paper
Meterstick and/or metric ruler
Small length of string
Graduated cylinder

Safety:

Safety goggles and lab aprons should be worn to protect eyes and clothing. This is especially important when working with the latex and sodium silicate polymer experiments.
If a chemical gets into eyes, immediately flush eyes with water.
Elmer's® White Glue-All and Blue Glue Gel are nontoxic, but should not be ingested.
Borax is sodium tetraborate decahydrate. It is an eye irritant.
Liquid Latex is preserved in ammonia and has a very strong odor. Do not inhale. It may also irritate skin, so handle with gloves. If it comes in contact with skin, wash thoroughly with soap and water.
5% acetic acid solution is the same as household vinegar.
Sodium silicate solution is irritating to skin. Handle with gloves.
Ethanol is flammable. Keep away from flames.
For Material Safety Data Sheets (MSDS) on these chemicals, click here.

Experiment:

Preparation: Construct polymer balls according to procedures in the table below.

Polymer Balls

Ball #1
Elmer's® White Glue-All and Borax Powder Ball #2
Elmer's® Blue Glue Gel and Borax Solution Ball #3
Liquid Latex and Acetic Acid Solution Ball #4
Sodium Silicate Solution and Ethanol Solution

Procedure for Ball #1

Measure 30 mL (2 tbsp) of glue into a plastic cup with the 30 mL level marked.*

Add approximately 1 gram (1/2 tsp) of Borax powder to the glue.

Stir until the mixture clumps and sticks to the stirring rod or stick.

Remove the clump of polymer from the stick. Hold it under running water and shape into a ball.

Pat the ball dry and bounce it on the table top.

Save for activities.

*Prior to use, the 30 mL (or 15 mL) mark can be determined by adding 30 mL (or 15 mL) of water, (measured in a graduated cylinder) to the cup. The level can be marked, and the cup emptied and dried. Procedure for Ball #2

Measure 30 mL (2 tbsp) of glue into a plastic cup with the 30 mL level marked.*

To prepare borax solution, add approximately 1 gram (1/2 tsp) of borax powder to 2.5 mL (1/2 tsp) of tap water. Stir until powder is wet.

Add borax solution to the glue.

Stir until the mixture clumps and sticks to the stirring rod or stick.

Remove the clump of polymer from the stick. Hold it under running water and shape into a ball.

Pat the ball dry and bounce it on the table top.

Save for activities.

Procedure for Ball #3
NOTE: This procedure should be done under a fume hood or in a well-ventilated area.

Measure approximately 15 mL (1 tbsp) of liquid latex rubber into a marked plastic cup.*

Pour 15 mL (1 tbsp) of water into the liquid rubber and stir to mix.

Using a dropper, slowly add 15 mL (1 tbsp) of 5% acetic acid solution (household vinegar) to the latex, while continuously stirring.

When the mixture takes on the consistency of "rubber," remove it from the cup. Hold it under running water and shape into a ball.

Pat the ball dry and bounce it on the table top.

Save for activities.

Procedure for Ball #4

Measure 12 mL of sodium silicate solution and pour into a plastic cup.

Measure 3 mL of 50% ethanol.

Add the ethanol to the sodium silicate solution. Mix until a solid substance forms.

While wearing gloves, remove the polymer and place it in the palm of one hand.

Gently press it until a ball forms that does not crumble. A mixture of ethanol and water will come out of the ball as you work with it.

Occasionally moisten the ball by holding it under running water.

Pat the ball dry and bounce it on the table top.

Save for activities.

Investigations: Compare properties of the polymer balls .

Physical Appearance:

Density:

Bounce Height:

Temperature Changes:

Exposure to Air:

Results:

Design a table to compare data collected from investigations.
Make comparisons for each type of ball.
Using structural formulas for various monomers, illustrate the two general types of polymerization.
Investigate sodium silicate solution to determine its composition.

Suggestions for Assessment:

Click Here for a Printable Quiz for Level 3
Student Journal or Report

Extensions:

Compare properties of polymer balls made in the lab to commercial rubber ball(s).
Design an inquiry lab to compare properties of polymer balls when reagent amounts are altered.
As an integrated math activity, use the CBL or CBR motion detectors and calculators to analyze graphs of ball rebound height.

Level 3 Page

Main Page

Polymer Balls
Ball #1 Elmer's® White Glue-All and Borax Powder	Ball #2 Elmer's® Blue Glue Gel and Borax Solution	Ball #3 Liquid Latex and Acetic Acid Solution	Ball #4 Sodium Silicate Solution and Ethanol Solution
Procedure for Ball #1 Measure 30 mL (2 tbsp) of glue into a plastic cup with the 30 mL level marked.* Add approximately 1 gram (1/2 tsp) of Borax powder to the glue. Stir until the mixture clumps and sticks to the stirring rod or stick. Remove the clump of polymer from the stick. Hold it under running water and shape into a ball. Pat the ball dry and bounce it on the table top. Save for activities. *Prior to use, the 30 mL (or 15 mL) mark can be determined by adding 30 mL (or 15 mL) of water, (measured in a graduated cylinder) to the cup. The level can be marked, and the cup emptied and dried.	Procedure for Ball #2 Measure 30 mL (2 tbsp) of glue into a plastic cup with the 30 mL level marked.* To prepare borax solution, add approximately 1 gram (1/2 tsp) of borax powder to 2.5 mL (1/2 tsp) of tap water. Stir until powder is wet. Add borax solution to the glue. Stir until the mixture clumps and sticks to the stirring rod or stick. Remove the clump of polymer from the stick. Hold it under running water and shape into a ball. Pat the ball dry and bounce it on the table top. Save for activities.	Procedure for Ball #3 NOTE: This procedure should be done under a fume hood or in a well-ventilated area. Measure approximately 15 mL (1 tbsp) of liquid latex rubber into a marked plastic cup.* Pour 15 mL (1 tbsp) of water into the liquid rubber and stir to mix. Using a dropper, slowly add 15 mL (1 tbsp) of 5% acetic acid solution (household vinegar) to the latex, while continuously stirring. When the mixture takes on the consistency of "rubber," remove it from the cup. Hold it under running water and shape into a ball. Pat the ball dry and bounce it on the table top. Save for activities.	Procedure for Ball #4 Measure 12 mL of sodium silicate solution and pour into a plastic cup. Measure 3 mL of 50% ethanol. Add the ethanol to the sodium silicate solution. Mix until a solid substance forms. While wearing gloves, remove the polymer and place it in the palm of one hand. Gently press it until a ball forms that does not crumble. A mixture of ethanol and water will come out of the ball as you work with it. Occasionally moisten the ball by holding it under running water. Pat the ball dry and bounce it on the table top. Save for activities.