Question

Which (if any) of the following compounds are nonelectrolytes? (a) citric acid \(\left(\mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{7}\right)\) (b) calcium nitrate, \(\mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}\) (c) ammonium carbonate, \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{CO}_{3}\) (d) iodine tribromide \(\left(\operatorname{IBr}_{3}\right)\)

Short answer

(a) Citric acid \(\left(\mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{7}\right)\) (b) Calcium nitrate, \(\mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}\) (c) Ammonium carbonate, \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{CO}_{3}\) (d) Iodine tribromide \(\left(\mathrm{IBr}_{3}\right)\) Answer: (a) Citric acid and (d) Iodine tribromide are nonelectrolytes.

Step-by-step solution

Identify ionic or covalent bonds in each compound

Ionic compounds are typically formed when a metal bonds with a nonmetal, while covalent compounds usually occur when two nonmetals bond together. If the compound contains a polyatomic ion, consider whether the ion dissociates or not. (a) Citric acid \(\left(\mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{7}\right)\): Contains only nonmetals (C, H, O). (b) Calcium nitrate, \(\mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}\): Contains a metal (Ca) and a polyatomic ion (NO3). (c) Ammonium carbonate, \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{CO}_{3}\): Contains polyatomic ions (NH4) and (CO3). (d) Iodine tribromide \(\left(\mathrm{IBr}_{3}\right)\): Contains only nonmetals (I, Br).

Analyze solubility and dissociation of compounds

Ionic compounds and molecular compounds with polar covalent bonds are usually soluble in water. However, only ionic compounds will dissociate into ions when dissolved, making them electrolytes. Molecular compounds, despite being soluble, will not dissociate into ions, making them nonelectrolytes. (a) Citric acid: A molecular compound with polar covalent bonds; soluble but does not dissociate. It is a nonelectrolyte. (b) Calcium nitrate: Ionic compound; soluble and dissociates into ions. It is an electrolyte. (c) Ammonium carbonate: Ionic compound; soluble and dissociates into ions. It is an electrolyte. (d) Iodine tribromide: A molecular compound with polar covalent bonds; soluble but does not dissociate. It is a nonelectrolyte.

Conclusion

Among the given compounds, citric acid \(\left(\mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{7}\right)\) and iodine tribromide \(\left(\operatorname{IBr}_{3}\right)\) are nonelectrolytes, as they are molecular compounds with covalent bonds that do not dissociate into ions when dissolved in water.