7.4 BALANCIN G CHEMICAL EQUATION S Patrick Mattoon Keller Bean Griffin Rice.

7.4 BALANCINGCHEMICAL

EQUATIONS Patrick Mattoon

Keller BeanGriffin Rice

THE LAW OF CONSERVATION OF MASS

Chemical reactions are rearranged, never added or destroyed

Each side of the equation must have an equal number of atoms for each element

The mass of the reactants must equal the mass of the products

BALANCING EQUATIONS Balanced Equation: each side of the

equation has the same number of atoms of each element

In the equation if you label the state of matter, the symbol (g,s,l,or aq) is put directly following the formulaEx.) SnO2(s)

Balance the metals before nonmetals

RULES FOR BALANCING EQUATIONS1. Write the equation (leave spaces in front of the

formulas for coefficients)

2. Add the subscripts of each separate atom on either side of the equation

3. Balance chemical formulas by placing coefficients in front of them. Do not add or change subscripts, that will change the formulas

4. Make sure all of the coefficients are in the lowest possible ratio

5. Check to make sure the number of each atom is equal on either side of the equation

http://chemistry.about.com/cs/stoichiometry/a/aa042903a.htm

D. Fe2O3+2C 2Fe+4CO2

B. 2Fe2O3+3C 4Fe+3CO2

Fe2O3+C Fe+CO2

A. 6Fe2O3+6C 3Fe+2CO2

C. 3Fe2O3+4C 6Fe+3CO2

COMBUSTION

C H O

Always balance the carbon and hydrogen atoms before the oxygen

atoms

HOMEWORK PROBLEMS

a) 2KClO3 KCl+O2

b) 2Na+Cl2 NaCl

c) P4O10+H2O H3PO4

THE ENDThe End