Chemical Reactions

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

Reactants: The elements or compounds present at the beginning of a chemical reaction

Products: The elements or compounds produced at the end of a chemical reaction

Chemical reactions: Always involve changes in the chemical bonds that joins atoms in compounds.

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

6CO 2 This Molecule is called…. Carbon Dioxide Number of molecules…. 6 Number of Carbon atoms…. 6 Number of Oxygen atoms… 12

6H 2 O a) This Molecule is called…. Water Number of molecules…. 6 Number of Hydrogen atoms…. 12 Number of Oxygen atoms… 6

Glucose: C 6 H 12 O 6 b) Glucose or Sugar: Number of molecules…. 1 Number of Carbon Atoms… 6 Number of Hydrogen atoms…. 12 Number of Oxygen atoms… 6

6O 2 c) Oxygen…. Number of molecules…. 6 Number of Oxygen atoms… 12

How many TOTAL ATOMS of each element are present on the REACTANTS side of the reaction: Carbon: ___________ Oxygen: _____________ Hydrogen: ____________

How many TOTAL ATOMS of each element are present on the PRODUCTS side of the reaction: Carbon: ___________ Oxygen: _____________ Hydrogen: ____________

If you did your math correctly in step d. and e. you have observed a fundamental scientific principle called THE CONSERVATION OF MATTER. Using the information you gained in part d. and e. explain what the conservation of matter is using the sentence starter provided: The principle of the conservation of matter is demonstrated by the chemical reaction above because:

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

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

Apply what you’ve LEARNED b.) 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 c.) 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. Energy in Reactions: Energy is absorbed or released whenever chemical bonds form or are broken.

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.

The speed of a reaction depends on whether is absorbs or releases energy.

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

Enzyme Active Site pH Change: 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 2) _ Cu + _ S  _ Cu 2 S 1) _ Na + _ O 2  _ Na 2 O 3) _ CuO + _ H 2  _ Cu + _ H 2 O