Activity 19Activity 19Creating New MaterialsCreating New Materials

Read B-39Challenge Question:

How are reactants changed by a chemical reaction? How are the products different?

In this activity you will start with the polymer known as polyvinyl alcohol (PVA) and see how its properties change when it is mixed and reacts chemically with another compound, to change its molecular composition.

Background Information• Chemical reactions occur in everyday life during such

activities as cooking, cleaning, and bleaching laundry. However, chemical reactions cannot be observed at the molecular level, and people generally use indirect indicators to infer that chemical reactions have taken place. For example, the appearance of bubbles when acid is added to aluminum is evidence that a new substance—a gas—is formed. In this activity, a chemical reaction between polyvinyl alcohol (a polymer) and sodium borate will occur. We cannot directly observe the rearrangements of atoms at the molecular level, so we must look for evidence of new chemical or physical properties that indicate a new substance has formed. Evidence that a chemical reaction may be occurring includes the following:

• color change• formation of a new substance with properties different

from the original reactants• emission of a gas• emission or absorption of heat (detected by a change in

temperature)• emission of light or sound

Iron powder and sulfur are mixed. A heated metal rod initiates an

exothermic reaction

Create this molecule- vinyl alcohol

H H C C H O H

Polyvinyl Alcohol Molecule• You can use all of these single molecules

to build a long chain.• Use extra bonds to link your molecule to

the other molecules.• You modeled a chemical reaction between

vinyl alcohol molecules.• One Vinyl Alcohol Molecule = monomer• Long Chain Polyvinyl Alcohol = polymer• 1,000-10,000 monomers form a polymer.• You will be using Polyvinyl Alcohol today.

Examples of Plastics

• Polypropylene (Blue)• Polyvinyl Chloride (Green)• High Density Polyethylene (Red)• Polystyrene (Yellow)

• What do you notice about the names of these materials?

We made Polyvinyl Alcohol

• “Polymers” are long chains made up of smaller molecules called “monomers”

• “Poly” means many

• “Mono” means one

Safety:

Wear safety goggles at all times during this lab. Do not allow solutions to touch your skin or clothing. Clean up any spills immediately. If accidental contact occurs, inform your teacher, and rinse exposed areas.

Procedure:

Follow procedure on pages B-40 to B-41.

Clean and dry the materials quickly!!!!

Data/Evidence:

Glue table provided into your Glue table provided into your notebook. Don’t forget to put a notebook. Don’t forget to put a capital E in a blue circle in the capital E in a blue circle in the margin of your table.margin of your table.

Clean up

• Each Bin Needs:4 cleaned and dried

cups2 clean spoons2 stir sticks2 paper towel (KEEP

IT DRY!)1 bottle of PVA1 bottle of Sodium

Borate

• Return finished bins to side benches

• Wash hands (all students)

• Wipe off desk with paper towel

• Atoms– 4 white, 2 black, 1 red, and 7 white plastic “bonds”

Analysis:

Do analysis questions 1 and 2.Do analysis questions 1 and 2.

If time allows, go over the analysis If time allows, go over the analysis questions as a group to get ideas and questions as a group to get ideas and discuss/compare results. Write well discuss/compare results. Write well developed thorough answers. Use as developed thorough answers. Use as much evidence as possible to much evidence as possible to support your answers.support your answers.

Follow-up:Follow-up:

• Which do you think is a harder Which do you think is a harder substance, a polymer with more substance, a polymer with more cross-links or a polymer with fewer cross-links or a polymer with fewer cross-links?cross-links?

• What do you think would happen to What do you think would happen to the final polymer if you continued to the final polymer if you continued to add sodium borate?add sodium borate?