Question

Classify each of the following substances as a nonelectrolyte, weak electrolyte, or strong electrolyte in water: (a) HF, (b) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COOH}\) (benzoic acid), (c) \(\mathrm{C}_{6} \mathrm{H}_{6}\) (benzene), (d) \(\mathrm{CoCl}_{3}\), (e) \(\mathrm{AgNO}_{3}\).

Short answer

(a) Weak electrolyte, (b) Weak electrolyte, (c) Nonelectrolyte, (d) Strong electrolyte, (e) Strong electrolyte.

Step-by-step solution

Define electrolytes and nonelectrolytes

Electrolytes are substances that dissociate into ions when dissolved in water. Strong electrolytes completely dissociate into ions, while weak electrolytes only partially dissociate. Nonelectrolytes do not dissociate at all and do not produce ions in solution.

Analyze HF (hydrofluoric acid)

HF is a weak acid, meaning it only partially ionizes in water. This partial ionization classifies it as a weak electrolyte.

Analyze C6H5COOH (benzoic acid)

Benzoic acid is an organic acid known for only partially dissociating in water. Therefore, it is classified as a weak electrolyte.

Analyze C6H6 (benzene)

Benzene is a nonpolar organic compound that does not ionize in water, making it a nonelectrolyte.

Analyze CoCl3 (cobalt(III) chloride)

CoCl3 is an ionic compound. Ionic compounds typically dissociate completely in water, making it a strong electrolyte.

Analyze AgNO3 (silver nitrate)

AgNO3 is another ionic compound found to dissolve completely in water, so it is classified as a strong electrolyte.

Key concepts

Nonelectrolytes

Nonelectrolytes are substances that do not dissociate into ions in solution. When they are dissolved in water, they remain intact as molecules. This means they do not conduct electricity because there are no charged particles available to carry the current. Examples include many organic compounds like sugars and alcohols. These substances are often characterized by their covalent bonds, where electrons are shared rather than transferred. Understanding nonelectrolytes is essential because they show a different behavior compared to electrolytes in aqueous solutions. In the original example, benzene (
C ) is classified as a nonelectrolyte due to its inability to ionize in water.

Weak Electrolytes

Weak electrolytes partially dissociate into ions when dissolved, resulting in a mixture of ions and undissociated molecules in the solution. Weak acids and bases are typical examples. They demonstrate limited electrical conductivity due to the lower number of ions generated. Hydrofluoric acid (HF) and benzoic acid ( 
COOH) are weak electrolytes since they only partially ionize in water. This incomplete ionization is crucial to recognize because it affects how these substances behave in chemical reactions and equilibria.

Strong Electrolytes

Strong electrolytes are substances that completely dissociate into ions in an aqueous solution. This full dissociation enhances their ability to conduct electricity effectively. Typically, strong acids, strong bases, and most ionic compounds fall under this category. Silver nitrate ( AgNO) and cobalt(III) chloride ( CoCl) in the provided examples are considered strong electrolytes because they dissolve entirely into their respective ions. Understanding strong electrolytes is critical, as they play significant roles in various chemical processes, including reactions and solution chemistry.

Ionic Compounds

Ionic compounds consist of positively and negatively charged ions held together by ionic bonds. These bonds result from the transfer of electrons between atoms, generally a metal and a non-metal. In water, ionic compounds dissociate into their component ions, making them strong electrolytes. Common examples include salts like sodium chloride ( NaCl) and our earlier mentioned AgNO and CoCl. Comprehending ionic compounds is fundamental in chemistry, as they are abundant and exhibit unique properties compared to covalent compounds.

Organic Acids

Organic acids are a type of weak acid containing carbon and having a carboxyl group (-COOH). In water, they partially ionize, forming hydrogen ions (H ) and the corresponding organic anions. Benzoic acid ( 
COOH) is an example, which only partly dissociates in solution. This partial dissociation is significant, influencing how organic acids participate in reactions and equilibria. Organic acids' strength and behavior in solutions vary, making them an interesting subject for further study in chemistry.