Chemical Equations
     Reactants – the substances that undergo change in a 
     chemical reaction. 
     Products – The new substances formed as a result of 
     a chemical reaction
           Reactants             Products
     Chemical Equation – a representation of a chemical 
     reaction in which reactants and products are 
     represented as formulas
    Conservation of Mass
     The law of conservation of mass states that mass 
     neither created nor destroyed in a chemical 
     reaction.
     Example: How is the law of conservation of mass 
     represented with a piece of charcoal?
  Conservation of Mass (Cont.)
    Balancing Equations
     Water is formed by the reaction of hydrogen and 
     oxygen. The reaction can be described by a 
     chemical equation. 
               H₂  + O₂                    H₂O
     A chemical equation must be balanced in order to 
     show that mass is conserved in a chemical reaction. 
    Balancing equations (Cont.)
     Coefficients – The numbers that appear before the 
     formulas; these can be changed to balance the 
     equation.
     When there is no coefficient in front of the chemical 
     formula, then it is understood to be 1.
     ***Subscripts should never be changed !!!