Video Transcript
What is the equation for the
solubility product of vanadium(III) carbonate, V2(CO3)3?
This question is asking us to
determine the equation for the solubility product of the compound given. The solubility product, or K sp, is
the product of the concentrations of the ions in a saturated solution raised to the
power of their respective stoichiometric coefficients. For example, a generic insoluble
solid can be represented with the formula MA. Even if it is considered insoluble,
a compound likely exists in equilibrium with water and some slight dissolution
occurs. We can express this dissolution
with M1+ and A1− ions as aqueous products.
In this generic equation, lowercase
𝑚 and 𝑎 represent the stoichiometric coefficients of the ions. We can use this equilibrium
reaction to write the solubility product equation. The K sp equals the concentrations
of the ions multiplied together. We show them in brackets to
represent their concentrations. Often, the unit that is used to
measure concentration is moles per liter. These concentrations are raised to
the power of their coefficients.
Let’s apply this to vanadium(III)
carbonate. We are given the chemical formula
for vanadium(III) carbonate, which is V2(CO3)3, which we can write as a single solid
reactant. The Roman numeral III in the
vanadium(III) ion name indicates that this cation has a three-plus charge state. The carbonate anion has a two-minus
charge. From the chemical formula of the
compound, we can see that for each equivalent of reactant dissolved, there are two
vanadium(III) ions produced. And for every two vanadium(III)
ions present, there are three carbonate ions in solution.
Now that we have written the
balanced equilibrium reaction for the dissolution of vanadium(III) carbonate, we can
write the equation for the solubility product. First, we write vanadium(III) and
carbonate ions multiplied by one another. We write them in brackets to
indicate their concentrations. Then, we raise the concentration of
each ion to their stoichiometric coefficient.
Therefore, the equation for the
solubility product of vanadium(III) carbonate, V2(CO3)3, is K sp equals the
concentration of V3+ raised to the second power times concentration of CO32− raised
to the third power.
