Chemical Reactions

Chemical Reactions and Enzymes What does a chemical formula tell you? ________________________ ____________________________________ Draw and label a chemical formula: CO 2 + H 2 O  H 2 CO 3 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 ReactantsProducts

How many molecules are in a chemical formula/equation? Photosynthesis: Put a box around the products and circle reactants carbon dioxide + water  glucose + oxygen ReactantsProducts chemical equation: CO 2 + H 2 O  C 6 H 12 O 6 + O 2 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: CO 2 + H 2 O  C 6 H 12 O 6 + O 2 balanced chemical equation 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2

Using the Equation for Wood Burning: Answer the questions Write this equation down! C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O

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 C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O

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 ! C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O

C. 3) How many elements are on the: Reactant Side: 3 Product Side: 3 What are the elements? Carbon Hydrogen Oxygen C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O

Apply what you’ve LEARNED 4.) 2 H 2 O 2  2H 2 O + O 2 # of reactant molecules: 2 # of product molecules: 3 a.) What are the molecules: Hydrogen Peroxide Water Oxygen

Apply what you’ve LEARNED 5.) 2 H 2 O 2  2H 2 O + O 2 # of reactant atoms: 8 (4 H and 4 O) # of product atoms: 8 (4H, 2O, 2O)

Apply what you’ve LEARNED 6.) 2 H 2 O 2  2H 2 O + O 2 # 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: Reactants Products Activation Energy Activation energy Energy AbsorbingEnergy 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. H 2 + O 2  H 2 O 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 H 2 + O 2  2H 2 O 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. 2H 2 + O 2  2H 2 O 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 cells Reactants: Hydrogen peroxide Reactants Hydrogen Peroxide

Enzyme Active Site Enzyme: Peroxidase in liver cells Reactants: Hydrogen peroxide Reactants=Substrate

Enzyme Active Site Enzyme: Peroxidase in liver cells Products: Water and Oxygen Product O2O2 H2OH2O

Enzyme Active Site Product Enzyme: Peroxidase in liver cells Products: Water and Oxygen More Hydrogen Peroxide O2O2 H2OH2O

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  _ Cu 2 S 2) _ Na + _ O 2  _ Na 2 O 3) _ CuO + _ H 2  _ Cu + _ H 2 O