You choose to investigate some of the solubility guidelines for two ions not
listed in Table 4.1, the chromate ion \(\left(\mathrm{CrO}_{4}{ }^{2-}\right)\)
and the oxalate ion \(\left(\mathrm{C}_{2} \mathrm{O}_{4}{ }^{2-}\right)\). You
are given \(0.01 \mathrm{M}\) solutions (A, B, C, D) of four water-soluble
salts:
$$
\begin{array}{lll}
\hline \text { Solution } & \text { Solute } & \text { Color of Solution } \\
\hline \mathrm{A} & \mathrm{Na}_{2} \mathrm{CrO}_{4} & \text { Yellow } \\
\mathrm{B} & \left(\mathrm{NH}_{4}\right)_{2} \mathrm{C}_{2} \mathrm{O}_{4} &
\text { Colorless } \\
\mathrm{C} & \mathrm{AgNO}_{3} & \text { Colorless } \\
\mathrm{D} & \mathrm{CaCl}_{2} & \text { Colorless } \\
\hline
\end{array}
$$
When these solutions are mixed, the following observations are made:
$$
\begin{array}{lll}
\hline \text { Expt } & \text { Solutions } & \\
\text { Number } & \text { Mixed } & \text { Result } \\
\hline 1 & \mathrm{~A}+\mathrm{B} & \text { No precipitate, yellow solution }
\\\
2 & \mathrm{~A}+\mathrm{C} & \text { Red precipitate forms } \\
3 & \mathrm{~A}+\mathrm{D} & \text { No precipitate, yellow solution } \\
4 & \mathrm{~B}+\mathrm{C} & \text { White precipitate forms } \\
5 & \mathrm{~B}+\mathrm{D} & \text { White precipitate forms } \\
6 & \mathrm{C}+\mathrm{D} & \text { White precipitate forms } \\
\hline
\end{array}
$$
(a) Write a net ionic equation for the reaction that occurs in each of the
experiments. (b) Identify the precipitate formed, if any, in each of the
experiments. (c) Based on these limited observations, which ion tends to form
the more soluble salts, chromate or oxalate?
