Transcript Activity 19: Creating New Materials

1. Write down new vocabulary
2. Stamp Activity 17 & Isotopes
Youtube Periodic Table- Bromine
Activity 19
Title: Creating New Materials
Read B-39
Problem: How are reactants changed by a
chemical reaction? How are the products
different?
Hypothesis/Initial Thoughts:
Background:
Chemical Reactions
•occur during every day activities like cooking,
cleaning and bleaching laundry
•can’t be observed at a molecular level
•generally use indirect indicators to infer that a
chemical reaction has taken place
 Color change
 Formation of a new substance with properties different
from the original reactant
 release of a gas
 heat given off or absorbed
 light or sound given off
Iron powder and sulfur are mixed. A heated metal rod initiates an exothermic reaction
Background cont.:
• Examples of chemical reactions:
– Burning fuel to heat homes
– Combustion of gasoline to power cars
– The human body using a reaction between
food and oxygen to produce carbon dioxide
and water, releasing energy
– Baking bread or cookies
Background: Create this molecule
Vinyl alcohol
H
H
C
H
C
O
H
Draw it in your
notebook
Link your vinyl alcohols together
• 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 function of a model is to make simple
representations of complex systems
• Molecular models allow us to visualize what
is happening at the molecular level
We made Polyvinyl Alcohol
• You will be using Polyvinyl Alcohol today.
• The long chain is called a polyvinyl
alcohol, because “poly-” means many. In
any reaction like this, the starting subunit
part is called a monomer, which means
“one part”, and the resulting chain of many
parts is called a polymer, which means
“many parts”
Background cont.:
• One Vinyl Alcohol Molecule = monomer
• Long Chain Polyvinyl Alcohol = polymer
– 1,000-10,000 monomers form a polymer.
• “Poly” means many
• “Mono” means one
Polyvinyl Alcohol
More
monomer
links
H
C
H
H
H
C
C
O
H
H
H
More monomer
links
C
O
H
Draw it in
your
notebook
Background cont.:
Reactants + Reactant
Product + Product
Sodium and Water Demo:
2Na + 2H2O
2NaOH + H2
Reactant: a substance that undergoes change in a
chemical reaction
Product: a substance formed as a result of a
chemical reaction
Examples of Plastics
•
•
•
•
Polypropylene (Blue)
Polyvinyl Chloride (Green)
High Density Polyethylene (Red)
Polystyrene (Yellow)
What do you notice about the names of
these materials?
Read Steps 1-8 on B40 to B41
• LEAVE ROOM (AT LEAST 10 LINES)
FOR YOUR DATA TABLE!!
What will be our evidence of a
chemical reaction?
What are some of the rows that we will need
to label on our data table??
What will be our evidence of a
chemical reaction?
Color
How does it pour?
Can it be stirred?
Stickiness
Bounciness
Stretchiness
Other Observations
• 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.
• Stir the mixture constantly and slowly
until a gel forms
• Clean and dry the materials quickly!!!!
• Everyone wash your hands after you
have put away your goggles and gloves
Follow-up
It is the number of cross-links that determines the
properties of a polymer
• Which do you think is a harder substance, a polymer
with more cross-links or a polymer with fewer crosslinks?
The sodium borate created the cross-links with the
polyvinyl alcohol
• What do you think would happen to the final polymer
if you continued to add sodium borate?
Cross-linked plastics are more rigid
Follow-up
• What are the physical properties of the
reactants?
• Describe the physical properties of the
product.
• What evidence show a new substance
was formed?
– change in physical properties indicates an
new substance has been formed