By: LoudElectronicFerocious & vballchiica Chemical Equations By: LoudElectronicFerocious & vballchiica

Law of Conservation of Mass In a chemical reaction, matter cannot be destroyed or created, though it can change form. It relates to balancing equations because when balancing an equation, you must end with the same amount of atoms as you started with. The law of conservation of mass was created by Antoine Laurent Lavoisier (1743-94)

Balancing Chemical Equations When balancing a chemical equation, first you must know what is the chemical formula. You cannot change that. Second, notice which atoms need to be doubled or tripled, any atoms with different subscript numbers. Write coefficients in front of the chemical formula, and only there. Do not put them in the middle of the formula.

Balancing Chemical Equation Balance the chemical equation. Double or triple the equation until the subscript number multiplied by the coefficient . Do not change the subscript numbers! Once the subscript numbers are equal when multiplied by the coefficient, rewrite it with the correct coefficient and the subscript numbers you started out with, and you have balanced an equation!

Examples H2 + O2 H2O Al + CuCl2 AlCl3 + Cu ^2 atoms^ 2 atoms^ ^1 atom 2^ 2^ 4^ 2^ 2 H2 + O2 2H20 4^ 2^ 4^ 2^ K + Br2 KBr 1^ 2^ ^1^ K + Br2 2KBr 1^ 2^ ^2^ 2K + Br2 2KBr2 2^ 2^ 2^ 2^ Al + CuCl2 AlCl3 + Cu 1^ 1^ 2^ 1^ 3^ 1^ 2Al + 3CuCl2 2AlCl3 + 3Cu 2^ 3^ 6^ 2^ 6^ 3^ 2Al + 3CuCl2 2AlCl3 + 3Cu 2^ 3^ 6^ 2^ 6^ 3^ N2 + H2 NH3 2^ 2^ 1^ 3^ N2 + H2 2NH3 2^ 2^ 2^ 6^ N2 + 3H2 2NH3 2^ 6^ 2^ 6^

Bold Definitions Chemical Equation- A representation of what happens to the chemicals in a chemical reaction. Chemical Formula- A formula in which only the elements and number of atoms of each element are shown. Subscript Number- A number below the line that represents the number of atoms of a particular element. Coefficient- The number that expresses the change or addition of atoms in the chemical formula.

Links http://misterguch.brinkster.net/eqnbalance.html http://dbhs.wvusd.k12.ca.us/webdocs/Equations/Conserv-of-Mass.html http://dbhs.wvusd.k12.ca.us/webdocs/Equations/Balance-Equation.html http://www.mikeblaber.org/oldwine/chm1045/notes/Stoich/Equation/coeff.gif http://everythingbio.com