Balancing Chemistry Balancing Chemistry RXNRXN

MAKING SENSE OF MAKING SENSE OF CHEMICAL EQUATIONSCHEMICAL EQUATIONS

•Communication is an important word Communication is an important word in today's world. One way chemists in today's world. One way chemists can communicate with information can communicate with information about a reaction is by writing a about a reaction is by writing a chemical equation. Chemical chemical equation. Chemical equations form an international equations form an international language. Chemists from different language. Chemists from different countries can communicate with countries can communicate with each other by equations.each other by equations.

What does an What does an equation show?equation show?

•It describes a real event.It describes a real event.

•It tells you which chemicals are It tells you which chemicals are reacting. reacting.

•It uses a chemical shorthand to It uses a chemical shorthand to describe a reaction. (symbols and describe a reaction. (symbols and formulae)formulae)

•It tells you how many particles are It tells you how many particles are involved. (atoms, molecules and ions)involved. (atoms, molecules and ions)

What does an What does an equation show? equation show?

•It tells you the number of moles of It tells you the number of moles of each substance that react together.each substance that react together.

•It tells you the number of moles of It tells you the number of moles of products formed. (These are the products formed. (These are the large numbers in front of the large numbers in front of the formulae)formulae)

•Many equations also show whether a Many equations also show whether a substance is a solid, liquid or gas or substance is a solid, liquid or gas or dissolved in water. (state symbols, dissolved in water. (state symbols, (s), (l), (g), or (aq).(s), (l), (g), or (aq).

WRITING CHEMICAL WRITING CHEMICAL EQUATIONSEQUATIONS

• Write the equation in words. Write the equation in words. Make sure you include all the reactants and all the products.Make sure you include all the reactants and all the products.

• Now write the equation in symbols, making sure you have Now write the equation in symbols, making sure you have used the correct formula for each substance. used the correct formula for each substance.

• Remember that the common gases are diatomic. ( they exist Remember that the common gases are diatomic. ( they exist as pairs) as pairs)

• Check the formula of each compound and do Check the formula of each compound and do notnot alter the alter the small numberssmall numbers that are part of the formula. that are part of the formula.

• If you cannot remember the correct formula, you will have to If you cannot remember the correct formula, you will have to work it out by the methods shown in the Chemical Formula work it out by the methods shown in the Chemical Formula Worksheet.Worksheet.