balancing equations



A balancing act.

What are they for?!?!

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

Why Do We Have to Balance?

• The law of conservation of matter states matter cannot be created or destroyed but can change from one form to another.

• Therefore, equations must be balanced!

• 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.

These numbers are found in a chemical equation:

Subscripts - The small numbers to the lower right of chemical symbols.

– Subscripts represent the number of atoms of each element in the molecule.

• PRACTICE.. #s 1 and 2 on notes sheet

Coefficients - The large numbers in front of chemical formulas. Coefficients represent the number of molecules of the substance in the reaction.

• PRACTICE… #3 on notes sheet

Chemical equations give information in two major areas

• First they tell us what substances are reacting and what substances are being produced.

Reactants  Products

• PRACTICE… #s 4 and 5 on notes sheet

How do we balance equations?

• Balance equations by changing coefficients

Never by changing formula subscripts

STEPS for Balancing!

1. Write all reactants on the left and all products on the right side of the equation arrow. Make sure you write the correct formula for each element.

2. Use coefficients in front of each formula to balance the number of atoms on each side.

3. Multiply the coefficient of each element by the subscript of the element to count the atoms.

Then list the number of atoms of each element on each side and make sure they are EQUAL!

Now… Let’s Practice

• #6 – 10 on notes sheet

• Website on laptops



– Write answers in comp book!