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Balancing Chemical Equations

Definitions

Law of Conservation of Mass- Mass is not created nor destroyed just transferred

                                     A balanced equation demonstrates that reactants are completely converted to products.

Reactants-the compounds that exist before a reaction has occurred.

Products-The compounds that exist after the reaction has occurred.

Coefficients-The number in front of a compound, element or ion. Determines the number of moles of that species.

Note-Chemist do not write 1's, we just write the formula. It does count as a 1, but it is not there.

             First let's read a chemical reaction.

2H_2(g) + O_2(g) ^==> 2H₂O_(l)

_{2 moles of hydrogen gas reacts with 1 mole of oxygen gas to form 2 moles of liquid water.}

+ means reacts with             ==> means to form

Past Regents Balancing Questions- Follow link for answers

Aug 2010-7 A balanced equation representing a chemical reaction can be written using
(1) chemical formulas and mass numbers
(2) chemical formulas and coefficients
(3) first ionization energies and mass numbers
(4) first ionization energies and coefficients

June 2006-7 Given the balanced equation representing a reaction:
F_2(g) + H_2(g) ==> 2HF_(g)
What is the mole ratio of H_2(g) to HF_(g) in this reaction?
(1) 1:1      (3) 2:1
(2) 1:2      (4) 2:3

Here are some videos to help you through this.

Chemical Demonstration Videos