Chemical Equation: a way to represent chemical reactions on paper.

Chemical Equation:a way to represent chemical reactions on paper. 2 H2 + O2--> 2 H2O

Reactants Products 2 H2 + O2--> 2 H2O BALANCED EQUATION 4 hydrogen2 oxygen 4 hydrogen 2 oxygen

Law of conservation of mass: “During a chemical rxn, atoms are neither created nor destroyed. The number of atoms remains constant throughout the reaction. Since the number of atoms doesn't change, the mass must remain constant as well”.

Equations must be balanced because:Atoms can be neither created nor destroyed in an ordinary chemical reaction, so there must be the same number of atoms on both sides of the equation.

Balance equations by changing coefficientsnever by changing formula subscripts

Interactive Tutorials on Balancing Equations GenChem - Balance Equation Click on this site: http://www.wfu.edu/~ylwong/balanceeq/balanceq.html

Drills 1: Balancing Equations • Na + O2 Na2O • H2 + O2  H2O • NaSO4 + CaCl2 CaSO4 + NaCl • Al2O3  Al + O2 • N2 + H2  NH3 2

Drills 2: Balancing Equations • Fe + H2O  Fe3O4 + H2 • P4 + O2 P4O10 • C2H6 + O2 CO2 + H20 • SiCl4  Si + Cl2 • C + H2  CH4

Drill # 1 2 Drill # 2

Chemical Equation: a way to represent chemical reactions on paper.