University:
Winston-Salem Forsyth County Schools
Course:
AP Chemistry
Academic year:

2015
Views:

30

Pages:

28
Author:

geraudservin2kur

Why are chemical reactions important???  Chemical reactions allow living things (cells, animals, people, insects) to grow, develop, reproduce, and adapt. What is a chemical reaction??  The process in which atoms or groups of atoms in substances are reorganized into different substances. How do you know when a chemical reaction has occurred???    Change in appearance Production of heat or light Formation of a new gas, liquid, or solid Why Chemical Formulas?  Scientists write chemical formulas to describe the substances in a reaction with arrows indicating the process of change. CO2 + 2H2O → CH4 + 2 O2 carbon dioxide and water = Methane + oxygen What is that the chemical equation for?!?!? CO2 + 2H2O → CH4 + 2 O2 It’s a fart!  The chemical equation shows the reactants, or the starting substances, on the left side of the arrow. CO2 + 2H2O → Carbon dioxide and water  The products are the substances formed during the reaction. These are the end results of the reaction and so are shown to the right side of the arrow. → CH4 + 2 O2 Methane and Oxygen  The arrow is read as “yields” or “react to form.”  Remember, matter cannot be created or destroyed! (The Law of Conservation of Mass) Therefore, it is important that we balance our chemical equations!!!  All chemical equations must show this balance of mass (things must be equal on each side.) But, HOW???  Coefficients are used to make the number of atoms on each side of the arrow equal!!! Let’s Try One!!!  C6H12O6+O2 CO2+H2O Glucose and Oxygen react to form Carbon Dioxide and Water C6H12O6+O2  On the reactant side, how many carbons do we have??? C6H12O6+O2  How many hydrogen atoms do we have? C6H12O6+O2  And how many Oxygen atoms?? •Don’t forget to add all of them together… So we must have 6 Carbon, 12 Hydrogen, and 8 Oxygen on the Products side.   CO2 + H2O Carbon Dioxide and Water What coefficient would need to be placed in front of the carbon to make it 6? 6CO2 + H2O So we must have 6 Carbon, 12 Hydrogen, and 8 Oxygen on the Products side.   But now you must multiply the coefficient by the # of Oxygen which is 2. 6x2=12… Hang on to this one. How many Hydrogen do we need? 6CO2 + H2O So we must have 6 Carbon, 12 Hydrogen, and 8 Oxygen on the Products side.   How can we have 12 Hydrogen??? Multiply the hydrogen by the coefficient… So, C6H12O6+__ O26CO2+6H2O     On Reactants Side: 6 Carbon 12 Hydrogen 8 Oxygen     On Products Side: 6 Carbon 12 Hydrogen 18 Oxygen What # + 6 = 18???? 12!!!  Can we multiply O2 by any number and get 12???  Balanced Equation is…  C6H12O6 + 6O2  6CO2 + 6H2O How do reactions occur???  The key to starting a chemical reaction is energy. Think baking cookies!!!  Most compounds in living things cannot undergo chemical reactions without energy!!! Activation Energy is…   The minimum amount of energy needed for reactants to form products in a chemical reaction. Ex: Burning a candle Animal Chemistry- Our Catalysts   Remember, a catalyst is a substance that lowers the activation energy needed to start a chemical reaction. Also, remember that the special proteins that act as biological catalysts are called enzymes. What should I know???   All chemical reactions in living things need catalysts called ENZYMES. The reactants that bind to the enzyme in a chemical reaction are called substrates.   And, the specific location where a substrate binds on an enzyme is called the active site. Once the substrate binds to the enzyme, bonds in the reactants are broken down quite easily and new bonds form- the substrates react to form products.