Chemical Equations
Chemical Equation Uses symbols and formulas to represent the products and reactants in a chemical reaction Equation must contain correct formulas of the reactants and the products
Word Equation Reactants and products represented by words Methane + Oxygen → Carbon dioxide + water “→” is read as yields
Formula Equation Formulas are substituted for words The equation below is the same as the last word equation with formulas instead CH4 + O2 → CO2 + H2O
Phases On Equations Phases of reactants and products can also be indicated in the equations (s) – solid (l) – liquid (g) – gas (aq) – aqueous (↑) – gas product (↓) – precipitate – solid product
Example HCl(aq) + Zn(s) → ZnCl2(aq) + H2(↑)
Law of Conservation of Matter Must always be satisfied in chemical reactions Number of each type of atom must be the same on both sides of the equation Atoms are neither created nor destroyed
Balancing Making the number of each type of atom the same on both sides of an equation Coefficient – whole numbers placed in front of the formulas You can only change coefficients when balancing – you can never change subscripts
Balance The Following CH4 + O2 → CO2 + H2O Fe + H2O → Fe3O4 + H2