Video Transcript
Consider the following
equation. Cl2 aqueous plus two NaBr aqueous
react to form Br2 aqueous plus two NaCl aqueous. What is the net ionic equation for
the displacement reaction between aqueous chlorine and sodium bromide?
The provided equation is a balanced
molecular equation. It shows the reaction between
aqueous chlorine, often called chlorine water, and an aqueous solution of sodium
bromide. The products of the reaction are
aqueous diatomic bromine and aqueous sodium chloride. Our job in this question is to
write a net ionic equation for this displacement reaction.
There are basic rules that we can
use to transform a molecular equation into an ionic equation and then into a net
ionic equation. First, we will need to split any
acids or ionic compounds that are dissolved in aqueous solutions into ions. The reactant sodium bromide, or
NaBr, is an ionic compound dissolved in an aqueous solution. The product sodium chloride, or
NaCl, is also an ionic compound dissolved in an aqueous solution.
Let’s get started by writing the
reactants of the ionic equation. Because there were two equivalents
of aqueous sodium bromide in the molecular equation, in our ionic equation, we will
write this as two sodium ions plus two bromide ions. In the ionic equation, we must also
include the charges of any dissolved ions and use the state symbol aq after each ion
symbol.
Now, let’s write the products of
the ionic equation. Because there were two equivalents
of aqueous sodium chloride in the molecular equation, in our ionic equation, we will
write this as two sodium ions plus two chloride ions. For each ion, we write the ionic
charge as a superscript and finish by writing the state symbol aq. Now that we have an ionic equation,
we need to convert it into a net ionic equation. To do so, we need to remove ions
that do not participate in the chemical reaction from our ionic equation. These ions are called spectator
ions.
During the chemical reaction,
diatomic chlorine molecules react to form chloride ions and displace bromide ions
from the sodium bromide solution. The bromide ions also react to form
diatomic bromine molecules. In contrast, the sodium ions are
spectator ions and do not participate in the chemical reaction. Therefore, the sodium ions should
not be included in our net ionic equation.
In conclusion, the net ionic
equation for the provided reaction is Cl2 aqueous plus 2Br− aqueous react to form
Br2 aqueous plus two Cl− aqueous.
