What are some common mistakes students make with stoichiometry of reactions between ions in solutions?

1 Answer
Jan 7, 2016

A failure to realize that BOTH mass and charge MUST be conserved in any chemical reaction.


Not only must mass be balanced in a chemical reaction, but charge must be balanced as well. If I start with 10 g, I must end with 10 g. Likewise, if the reactants have a certain charge, positive or negative, the products MUST have that same charge.

For example:

Lead nitrate + sodium chloride #rarr# Lead chloride#darr# + sodium nitrate.

As a net ionic equation:

#Pb^(2+) + 2Cl^(-) rarr PbCl_2(s)darr#

The reactants were neutral (#2^(+) + 2xx1^(-)#); so too the products!