Rubber Latex

Author(s): Craig Didden & Brandon Duran
Instrumentation - Teacher's Guide
SED 695B; Fall 2005
Overview: This experiment looks at the properties and chemistry of rubber latex. Rubber latex comes from the sap of rubber trees and is made of tiny particles or globules of rubber that are held suspended in water. When sap is collected, ammonia is added as a preservative to keep it from coagulating or clumping before use. When vinegar is added, an acid, to the latex, the vinegar reacts with the ammonia and neutralized it. Then the rubber coagulated.

This a picture of the instructional manual that comes with the kit.

     

Topics addressed:

Chemistry High School:

Students know definitions of solute and solvent.

Students know the atoms and molecules in liquids move in a random pattern relative to one another because the intermolecular forces are too weak to hold the atoms or molecules in a solid form.

Physical Science 8th grade 5:Students know reactant atoms and molecules interact to form products with different chemical properties
   
 

Procedure: 1. In one cup add one tablespoon of vinegar and two spoons of water.

2. Fill the other cup half way with water.

3. Add1/2 teaspoon of Rubber Latex into the cup with vinegar.

4.Stir with the spoon and try to form a glob of rubber into a ball.

5.Use the spoon and put the rubber ball in the cup from step 2 to wash it.

 

 

 

Questions: 1. List three characteristics of a solid, a liquid, and a gas.

2. What is a polymer?

3. Is the rubber latex a liquid or a soild after you placed it into the vinegar & water bath? Give evidence to support your claim.

4. How does the water & vinegar bath change the chemical make up of the rubber latex?

 

 
This picture shows a spoonful of Rubber latex before it was submerged in the cup of water and vinegar. Notice that the latex seems to be a liquid.
This picture shows a spoon ful of the Latex rubber after it was submerged in a cup of vinegar and water. Notice that the latex has clumped together to form a semi-solid substance.
This picture shows the Latex Rubber both before it was put into the vinegar and water, sample B, and after it was put into the vinegar and water, sample A. Notice the change in the shape of the Rubber Latex.
   

References & Links

What is a polymer?

http://www.google.com/search?hl=en&lr=&oi=defmore&defl=en&q=define:Polymer

Science Bits Chemisrty Kits

http://www.macnanbio.com/index.asp?PageAction=VIEWPROD&ProdID=1279&HS=1