Balancing Polyatomic Reactions with Color

General Chemistry Index

Balancing Polyatomic Reactions with Color

Once you have identified that the polyatomic chunks of an equation go through the reaction intact—that is they do not, in the products, appear differently than they did in the reactants—you can balance the equation by chunks and not actually keep up with the individual elements.

Color coding the chucks is one way to make this visually easier.

Fe(NO3)3 + (NH4)2CO3 → Fe2(CO3)3 + NH4NO3   <<<--- Unbalanced reaction

 

Fe(NO3)3 + (NH4)2CO3 → Fe2(CO3)3 + NH4NO3   <<<--- Unbalanced colorized reaction

 

            Reactant Side                    Product Side

Fe                 1                                           2

NO3              3                                            1

NH4              2                                            1

CO3              1                                            3

Color-coded, it becomes a matter of getting the same number of each color on each side. For instance, each side ends up with 6 "reds" and 6 "greens." This visual tool enhances awareness of the polyatomic ions moving across intactly.

2Fe(NO3)3 + 3(NH4)2CO3 → Fe2(CO3)3 + 6NH4NO3    <<<--- Balanced reaction

            Reactant Side                    Product Side

Fe                 2                                           2

NO3              6                                           6

NH4               6                                           6

CO3              3                                           3