Problem 204 - Introductory Chemistry Atoms First

Question

Indicate whether each compound is an electrolyte or a nonelectrolyte in water: (a) \(\mathrm{N}_{2}\) (b) \(\mathrm{NH}_{4} \mathrm{ClO}_{4}\) (c) \(\mathrm{HI}\) (d) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{3}\) (propane) (e) \(\mathrm{Li}_{3} \mathrm{PO}_{4}\) (f) \(\mathrm{AgNO}_{3}\) (g) \(\mathrm{CCl}_{4}\)

Step-by-Step Solution

Answer

(a) \(\mathrm{N}_{2}\): Nonelectrolyte (b) \(\mathrm{NH}_{4} \mathrm{ClO}_{4}\): Electrolyte (c) \(\mathrm{HI}\): Electrolyte (d) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{3}\): Nonelectrolyte (e) \(\mathrm{Li}_{3} \mathrm{PO}_{4}\): Electrolyte (f) \(\mathrm{AgNO}_{3}\): Electrolyte (g) \(\mathrm{CCl}_{4}\): Nonelectrolyte

Step 1: (a) Nitrogen Gas (\(\mathrm{N}_{2}\))

Nitrogen gas is a diatomic molecule and does not ionize in water. There are no free, mobile ions available to conduct electricity when it's dissolved. Therefore, \(\mathrm{N}_{2}\) is a nonelectrolyte.

Step 2: (b) Ammonium Perchlorate (\(\mathrm{NH}_{4} \mathrm{ClO}_{4}\))

Ammonium perchlorate is an ionic compound that dissociates into ammonium ions (\(\mathrm{NH}_{4}^{+}\)) and perchlorate ions (\(\mathrm{ClO}_{4}^{-}\)) when dissolved in water. This results in free, mobile ions that can conduct electricity. Thus, \(\mathrm{NH}_{4} \mathrm{ClO}_{4}\) is an electrolyte.

Step 3: (c) Hydrogen Iodide (\(\mathrm{HI}\))

Hydrogen iodide is a strong acid that undergoes ionization in water, forming hydrogen ions (\(\mathrm{H}^{+}\)) and iodide ions (\(\mathrm{I}^{-}\)). This means it contains free, mobile ions that can conduct electricity, so \(\mathrm{HI}\) is an electrolyte.

Step 4: (d) Propane (\(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{3}\))

Propane is a nonpolar covalent compound and does not ionize in water. The lack of free ions means it cannot conduct electricity when dissolved, so propane is a nonelectrolyte.

Step 5: (e) Lithium Phosphate (\(\mathrm{Li}_{3} \mathrm{PO}_{4}\))

Lithium phosphate is an ionic compound that dissociates into lithium ions (\(\mathrm{Li}^{+}\)) and phosphate ions (\(\mathrm{PO}_{4}^{3-}\)) when dissolved in water. This provides free, mobile ions for conducting electricity, making \(\mathrm{Li}_{3} \mathrm{PO}_{4}\) an electrolyte.

Step 6: (f) Silver Nitrate (\(\mathrm{AgNO}_{3}\))

Silver nitrate is an ionic compound that dissociates into silver ions (\(\mathrm{Ag}^{+}\)) and nitrate ions (\(\mathrm{NO}_{3}^{-}\)) when dissolved in water. These free, mobile ions allow it to conduct electricity, so \(\mathrm{AgNO}_{3}\) is an electrolyte.

Step 7: (g) Carbon Tetrachloride (\(\mathrm{CCl}_{4}\))

Carbon tetrachloride is a nonpolar covalent compound that does not ionize in water. As it lacks free ions to conduct electricity when dissolved, carbon tetrachloride is a nonelectrolyte.

Key Concepts

Ionic Compounds

Ionic compounds are fascinating due to their unique ability to form ions when dissolved in water. This occurs because ionic compounds consist of metals and nonmetals, where electrons are transferred from one atom to another, creating charged atoms called ions.

• These ions are held together by strong electrostatic forces.
• When placed in water, these compounds dissociate into their constituent ions.
• This dissociation allows the solution to conduct electricity, making ionic compounds electrolytes.

Examples include ammonium perchlorate (\[\mathrm{NH}_{4} \mathrm{ClO}_{4}\]) and silver nitrate (\[\mathrm{AgNO}_{3}\]), both of which dissociate into ions that freely move in solution.The presence of free ions is crucial for electrical conduction. Without them, the pathway for current flow is obstructed, and the compound would instead be a nonelectrolyte.

Covalent Compounds

Covalent compounds differ significantly from ionic compounds, as they involve the sharing of electrons rather than the transfer. This typically occurs between nonmetal atoms.

• No charged ions are formed in covalent bonding.
• The molecules of a covalent compound generally do not dissociate in water.
• Due to the lack of charged particles, these compounds do not conduct electricity.

For example, propane (\[\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{3}\]) and carbon tetrachloride (\[\mathrm{CCl}_{4}\]) are made up of covalent bonds. When dissolved in water, these molecules remain intact, resulting in no ions in solution and hence, no electrical conductivity.Covalent compounds can sometimes polarize, slightly affecting their solubility, but often, they remain poor conductors of electricity in water, marking them as nonelectrolytes.

Electrical Conductivity in Solutions

The electrolytic ability of a solution is heavily dependent on its contents and structure. Primarily, it relies on the presence of free ions in the solution.

• Electrolytes contain dissociated ions conducive to electrical flow.
• Strong acids like hydrogen iodide (\[\mathrm{HI}\]) also ionize in water, generating ions that enable electricity conduction.
• Nonelectrolytes, such as nitrogen gas (\[\mathrm{N}_{2}\]), lack free ions and cannot conduct electricity.

Ionic compounds generally serve as strong electrolytes due to the complete dissociation of ions in water. Meanwhile, covalent compounds tend to be nonelectrolytes because they do not break down into ions.
This understanding helps in predicting the behavior of various substances in solutions and their ability to conduct electricity efficiently. Comprehending these fundamental principles is key in both scientific research and practical applications, like designing batteries or treating water systems.