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Chemical Equations. Chemical Reactions - OVERVIEW. change that occurs when atoms rearrange themselves Can absorb or release energy Heat Light Sound Chemical equations used to describe chemical reactions. Think!.
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Chemical Reactions - OVERVIEW • change that occurs when atoms rearrange themselves • Can absorb or release energy • Heat • Light • Sound • Chemical equations used to describe chemical reactions
Think! What is an equation in math? What does it look like?Chemical equations in science are similar!
Chemical Equation • describes a chemical reaction C + O2 CO2, The carbon reacts with oxygen to yield carbon dioxide.
Parts of a Chemical Equation This reads “carbon plus oxygen react to yield carbon dioxide” C + O2 CO2 PRODUCTS Molecules that are formed in the reaction. REACTANTS Molecules that are used in the reaction. The arrow is read as “yields”
Identify the reactants and products: Key: CH4 = methane, NaCl= Sodium Chloride, Al2O3 = Aluminum Oxide
Lavoisier, 1788 Law of Conservation of Mass Matter can not be created or destroyed, although it may be rearranged.
Lavoisier, 1788 Chemical Equations Because of “Conservation of Mass”, chemical equations must be balanced Must have same number of each element on both sides of equation
Balanced or Unbalanced? A chemical equation must have the sameelements and number of atoms of each element on either side of the arrow in order to be balanced 2H2 + O2 2H2O • What elements do you have? Hydrogen Oxygen Hydrogen Oxygen
Balanced or Unbalanced? A chemical equation must have the same type and amount of atoms on either side of the arrow in order to be balanced A chemical equation must have the same type and amount of atomson either side of the arrow in order to be balanced 2H2 + O2 2H2O • How many atoms of each elements do you have? Hydrogen Oxygen Hydrogen Oxygen BALANCED = 4 = 4 = 2 = 2
Balanced or Unbalanced? Al + Br2 Al2Br6 • What elements do you have? Aluminum Bromine Aluminum Bromine
Balanced or Unbalanced? Al + Br2 Al2Br6 How many atoms of each elements do you have? Aluminum Bromine Aluminum Bromine = 1 = 2 = 2 = 6 *UNBALANCED*
Chemical Reactions & Equations – PRACTICE! K3PO4 + 2HCl 2KCl + H3PO4 Is this equation balanced? Reactants = Products K = 3 K = 2 P = 1 P = 1 O = 4 O = 4 H = 2 H = 3 Cl = 2 Cl = 2 No: K and H are not the same on both sides of the equation X