Multiple Choice
Which statement about solubility is true?
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6. Chemical Quantities & Aqueous Reactions
Solubility Rules
Multiple Choice
Which of the following solutions will form a precipitate when mixed with a solution of aqueous Na2CO3?
A
CaCl2(aq)
B
KNO3(aq)
C
NaCl(aq)
D
Li2SO4(aq)
Verified step by step guidance1
Identify the ions present in the aqueous sodium carbonate (Na2CO3) solution. It dissociates into 2 Na\(\textsuperscript{+}\) ions and 1 CO\(\textsubscript{3}\)\(\textsuperscript{2-}\) ion.
For each given solution, write down the ions it dissociates into when dissolved in water: CaCl\(\textsubscript{2}\) \(\rightarrow\) Ca\(\textsuperscript{2+}\) and 2 Cl\(\textsuperscript{-}\); KNO\(\textsubscript{3}\) \(\rightarrow\) K\(\textsuperscript{+}\) and NO\(\textsubscript{3}\[\textsuperscript{-}\); NaCl \(\rightarrow\) Na\(\textsuperscript{+}\) and Cl\(\textsuperscript{-}\); Li\(\textsubscript{2}\)SO\(\textsubscript{4}\) \(\rightarrow\) 2 Li\(\textsuperscript{+}\) and SO\(\textsubscript{4}\]\textsuperscript{2-}\).
Consider the possible combinations of cations and anions from Na2CO3 and each salt to see if any insoluble compound (precipitate) can form. Use solubility rules to determine if a precipitate forms. For example, carbonate salts of Ca\(\textsuperscript{2+}\) are generally insoluble.
Check the solubility rules: most carbonates (CO\(\textsubscript{3}\)\(\textsuperscript{2-}\)) are insoluble except those of alkali metals (like Na\(\textsuperscript{+}\), K\(\textsuperscript{+}\), Li\(\textsuperscript{+}\)) and ammonium. Since CaCO\(\textsubscript{3}\) is insoluble, mixing CaCl\(\textsubscript{2}\) with Na2CO3 will form a precipitate of CaCO\(\textsubscript{3}\).
Conclude that only the mixture of CaCl\(\textsubscript{2}\) and Na2CO3 will form a precipitate, while the others remain soluble due to the solubility of their respective ions with carbonate.
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