Chemical Reactions

Chemical Reactions and Enzymes

• What does a chemical formula tell you? ________________________

____________________________________Draw and label a chemical formula:

CO2 + H2O H2CO3

symbols, states, conditions, balanced

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

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

B. example:

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.chemical equation:

CO2 + H2O C6H12O6 + O2

balanced chemical equation

6CO2 + 6H2O C6H12O6 + 6O2

Using the Equation for Wood Burning: Answer the questionsWrite this equation down!

• 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 = 36This 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

C6H12O6 + 6O2 6CO2 + 6H2O

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 EnzymesIII. Label the graph:

Reactants

Products

Products

Activation Energy

Activation energy

Energy Absorbing Energy Releasing

Reactants

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

Enzyme

Active Site Reactants

III. How does an enzyme work?A. substrate binds to the enzyme

Substrate

Enzyme

Active Site

III. How does an enzyme work?A. substrate binds to the enzyme

Substrate

Enzyme

Active Site

III. How does an enzyme work?B. reactants converted to product

Product

Enzyme

Active Site

III. How does an enzyme work?C. products are released – enzyme is free to bind new substrate

Product

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 + O2 H2O

H=2 O=2 H=2 O=1

2. Place a coefficient next to each formula that needs to be increased and recount the atoms

H2 + O2 2H2O

H=2 O=2 H=4 O=2

3. Continue to add coefficients until the number of atoms is the same on both sides of the equation.

2H2 + O2 2H2O

H=4 O=2 H=4 O=2

Enzyme

Active Site

pH Change or boiling:

Product

No Product Made

Enzyme

Active Site

Inhibitor Molecules:

Product

Enzyme

Active Site

Enzyme: Peroxidase in liver cellsReactants: Hydrogen peroxide

ReactantsHydrogen Peroxide

Enzyme

Active Site

Enzyme: Peroxidase in liver cellsReactants: Hydrogen peroxide

Reactants=Substrate

Enzyme

Active Site

Enzyme: Peroxidase in liver cellsProducts: Water and Oxygen

Product

O2 H2O

Enzyme

Active Site

Product

Enzyme: Peroxidase in liver cellsProducts: Water and Oxygen

More Hydrogen Peroxide

O2

H2O

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) _ Cu + _ S _ Cu2S

2) _ Na + _ O2 _ Na2O

3) _ CuO + _ H2 _ Cu + _ H2O

2 1 1

214

1 1 1 1