Transcript Chemical Reactions

Chemical
Reactions
Chemical Reactions and
Enzymes
• What does a chemical formula
symbols, states,
tell you? ________________________
conditions, balanced
____________________________________
Draw and label a chemical
formula:
CO2 + H2O  H2CO3
Reactants
Products
Chemical Reactions and Enzymes
chemical reaction: process that
changes one set of compounds
(reactants) into another set of
compounds (products)
A. example:
wood + oxygen  carbon dioxide + water + energy
Reactants
Products
B. example:
How many molecules are in a chemical
formula/equation? Photosynthesis:
Put a box around the products and circle reactants
carbon dioxide + water  glucose + oxygen
Reactants
Products
chemical equation:
CO2 + H2O  C6H12O6 + O2
Reactants
Products
C. Conservation of matter: During a
chemical reaction, atoms are not
created or destroyed – just
rearranged. Therefore, chemical
equations must be balanced so there
is the same number of atoms on both
sides of the equation.
balancedequation:
chemical equation
chemical
CO22 ++ H

C
H
O
+
O
6CO
6H
O

C
H
O
+
6O
2O
6
12
6
2 2
2
6 12 6
Using the Equation for Wood
Burning: Answer the
questions
Write this equation down!
• C6H12O6 + 6O2  6CO2 + 6H2O
C6H12O6 + 6O2  6CO2 + 6H2O
C 1)How many molecules
are on the:
• Reactants side
•7
• Products Side
• 12
• What are the names of the
molecules:
• Glucose and Oxygen
• Carbon Dioxide and water
C6H12O6 + 6O2  6CO2 + 6H2O
C. 2) How many atoms
are on the:
Reactants side:
• 6 C, 18 O, 12 H
• Total = 36
• Products Side:
• 6 C, 18 O, 12 H
• Total = 36
This demonstrates the
conservation of Matter !
C6H12O6 + 6O2  6CO2 + 6H2O
C. 3) How many
elements are on the:
• Reactant Side:
•3
• Product Side:
•3
• What are the elements?
• Carbon
• Hydrogen
• Oxygen
Apply what you’ve LEARNED
4.) 2 H2O2  2H2O + O2
• # of reactant molecules: 2
• # of product molecules: 3
• a.) What are the molecules:
• Hydrogen Peroxide
• Water
• Oxygen
Apply what you’ve LEARNED
5.) 2 H2O2  2H2O + O2
• # of reactant atoms: 8
• (4 H and 4 O)
• # of product atoms: 8
• (4H, 2O, 2O)
Apply what you’ve LEARNED
6.) 2 H2O2  2H2O + O2
• # of reactant elements: 2
• # of product elements: 2
• What are the elements:
• Hydrogen
• Oxygen
II. Speed of Reactions
• The speed of a reaction
depends on whether is absorbs
or releases energy.
Chemical reactions that
Release energy….
• Often Occur Spontaneously
(without warning)
• Example: Explosion gun powder or
fireworks
Chemical reactions that
Absorb energy….
• Will not occur without a source
of energy.
• Example: Instant Ice Packs or
Photosynthesis.
Chemical Reactions and Enzymes
III. Label the graph:
Activation
energy
Products
Activation
Energy
Reactants
Energy Absorbing
Reactants
Products
Energy Releasing
A. All reactions require some energy
to start: activation energy.
Example: if some reactions that release energy did
not require activation energy, what could happen
to the pages of your text book as you sit here
reading?
They could spontaneously combust
into flames.
B. catalyst: substance that speeds up a
chemical reaction by lowering the
activation energy
Catalysts found in living things are
called enzymes
C. Enzymes
•provide a site where the reactants of
a chemical reaction can be brought
together
•are not used up or changed during
the chemical reaction
•active site: part of the enzyme where the
reactants bind (stick)
•reactants: molecules at beginning of a
chemical reaction. Called the substrate
when they encounter an enzyme.
•substrate only fits into the active site of
the correct enzyme (like a key and lock)
Labeled diagram:
Enzyme
Active Site
Reactants
III. How does an enzyme work?
A. substrate binds to the enzyme
Enzyme
Substrate
Active Site
Reactants
III. How does an enzyme work?
A. substrate binds to the enzyme
Enzyme
Substrate
Active Site
III. How does an enzyme work?
B. reactants converted to product
Enzyme
Product
Active Site
III. How does an enzyme work?
C. products are released – enzyme is
free to bind new substrate
Enzyme
Product
Active Site
IV. Enzymes
only work in specific
conditions
A. temperature: heat=destroy enzyme,
cold= slow enzyme down
B. pH: changes the shape of the enzyme
and its active site
C. coenzymes: make enzymes work better
D. inhibitor molecules: block substrate
from entering active site
Balancing Chemical
Equations
• A balanced equation shows that
every atom of the reactant
becomes part of the product.
• Atoms are never lost or gained.
• Balancing an equation may require
a coefficient, which is then given
to each atom in the formula.
Steps to Balancing an
Equation
1. Count the atoms of each
element in the reactants and
in the products.
H2
H=2
+ O2
O=2

H2O
H=2
O=1
2. Place a coefficient next to
each formula that needs to be
increased and recount the
atoms
H2
H=2
+ O2
O=2

2H2O
H=4
O=2
3. Continue to add coefficients
until the number of atoms is
the same on both sides of the
equation.
2H2
H=4
+ O2
O=2

2H2O
H=4
O=2
pH Change or boiling:
Enzyme
Product
Active Site
No Product
Made
Inhibitor Molecules:
Enzyme
Product
Active Site
Enzyme: Peroxidase in liver cells
Reactants: Hydrogen peroxide
Enzyme
Reactants
Hydrogen
Peroxide
Active Site
Enzyme: Peroxidase in liver cells
Reactants: Hydrogen peroxide
Enzyme
Reactants=Substrate
Active Site
Enzyme: Peroxidase in liver cells
Products: Water and Oxygen
Enzyme
Product
O2
H2O
Active Site
Enzyme: Peroxidase in liver cells
Products: Water and Oxygen
Enzyme
More
Hydrogen Peroxide
Active Site
O2
H2O
Product
Macromolecules
• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids
Carbohydrates
• Made of Sugar
• Main Source of energy
• Examples: Sugar
Lipids
• 1 Glycerol & 3 Fatty
Acids
• Stores energy
• Examples: Fats,
Cholesterol
Protein
• Amino Acids
• Makes up structures in
body
• Examples: Hair,
muscles, skin, bones,
etc.
Nucleic Acids
• Nucleotides
• Store genetic material
• Examples: DNA, RNA
Chemical Reactions and Enzymes
D. Practice: balance the following
equations
1) _2 Cu + _1 S  1_ Cu2S
2) 4_ Na + _1 O2  _2 Na2O
3) _1 CuO + _1 H2  1_ Cu + _1 H2O