Question

Identify each of the following substances as a strong electrolyte, weak electrolyte, or nonelectrolyte: (a) \(\mathrm{H}_{2} \mathrm{O},\) (b) \(\mathrm{KCl}\) (c) \(\mathrm{HNO}_{3},\) (d) \(\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2},\) (e) \(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\).

Short answer

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

Step-by-step solution

Understanding Electrolytes

Electrolytes are substances that dissociate into ions when dissolved in water. Strong electrolytes dissociate completely, weak electrolytes partially dissociate, and non-electrolytes do not dissociate at all.

Analyzing Water \\(\\mathrm{H_{2}O}\\)

Water is typically considered a nonelectrolyte because, although it can ionize slightly into hydrogen and hydroxide ions, it is not significant enough to label as an electrolyte.

Analyzing Potassium Chloride \\(\\mathrm{KCl}\\)

Potassium chloride is a strong electrolyte. When dissolved in water, it dissociates completely into potassium ions \(\mathrm{K^+}\) and chloride ions \(\mathrm{Cl^-}\).

Analyzing Nitric Acid \\(\\mathrm{HNO_{3}}\\)

Nitric acid is a strong electrolyte. It completely dissociates in water to produce hydrogen ions \(\mathrm{H^+}\) and nitrate ions \(\mathrm{NO_3^-}\).

Analyzing Acetic Acid \\(\\mathrm{HC_2H_3O_2}\\)

Acetic acid is a weak electrolyte. It partially dissociates into hydrogen ions \(\mathrm{H^+}\) and acetate ions \(\mathrm{C_2H_3O_2^-}\) in water.

Analyzing Sucrose \\(\\mathrm{C_{12}H_{22}O_{11}}\\)

Sucrose, a type of sugar, is a nonelectrolyte. It dissolves in water but does not dissociate into ions.

Key concepts

Strong Electrolyte

A strong electrolyte is a substance that, when dissolved in water, completely dissociates into its constituent ions. This means that no molecules of the original substance remain intact once it is in solution. This behavior is common in ionic compounds and strong acids or bases. For example, potassium chloride \(\mathrm{(KCl)}\) is a strong electrolyte. Upon dissolving in water, it fully separates into potassium ions \(\mathrm{(K^+)}\) and chloride ions \(\mathrm{(Cl^-)}\).

Characteristics of strong electrolytes include:

• High electrical conductivity in solution due to the abundance of free-moving ions.
• Complete ionization, meaning 100% of the compound dissociates.
• Examples include substances like \(\mathrm{HNO_3}\) (nitric acid) and \(\mathrm{NaOH}\) (sodium hydroxide).

Understanding the complete dissociation helps predict behaviors in chemical reactions and interactions in biological systems.

Weak Electrolyte

Weak electrolytes are substances that partially dissociate into ions in water. Only a small fraction of the molecules ionize, while the rest remain as whole molecules in solution. This results in a mixture of ions and molecules that cannot conduct electricity well.

Acetic acid \(\mathrm{(HC_2H_3O_2)}\) serves as a prime example of a weak electrolyte. When it dissolves in water, only a few acetic acid molecules dissociate into hydrogen ions \(\mathrm{(H^+)}\) and acetate ions \(\mathrm{(C_2H_3O_2^-)}\). The majority of the acetic acid remains undissociated as intact molecules.

Characteristics of weak electrolytes include:

• Limited electrical conductivity because of fewer ions present in the solution.
• Partial ionization, leading to equilibrium between dissociated ions and undissociated molecules.
• Common examples are weak acids, like \(\mathrm{HC_2H_3O_2}\) and weak bases like \(\mathrm{NH_3}\) (ammonia).

Comprehending these can assist in understanding reaction mechanisms and predicting the outcomes of dilutions.

Nonelectrolyte

A nonelectrolyte is a substance that does not dissociate into ions when dissolved in water. Instead, these substances dissolve by forming a solution without any ion formation. This means that the molecules remain whole, not forming any charged particles to carry electric current, making the solution non-conductive.

Sucrose \(\mathrm{(C_{12}H_{22}O_{11})}\), commonly known as table sugar, exemplifies a nonelectrolyte. When added to water, it dissolves as whole sugar molecules, without breaking up into ions.

Key traits of nonelectrolytes include:

• No ionization, hence, they do not conduct electricity in solution.
• Most often found in covalent compounds, especially organic ones.
• Examples include sugars and alcohols, like glucose and ethanol.

This understanding is vital in the realms of biochemistry and the design of non-conductive polymer materials.

Dissociation in Water

Dissociation in water is the process where compounds split into smaller particles, typically ions, when dissolved in water. This process plays a crucial role in determining whether a solution can conduct electricity. Electrolytes undergo dissociation, while nonelectrolytes do not.

When substances dissolve in water, they might behave differently depending on their chemical nature:

• Strong Electrolytes: Fully dissociate into ions, leading to a solution that can conduct electricity well.
• Weak Electrolytes: Partially dissociate, resulting in a mixture of ions and molecules with limited conductivity.
• Nonelectrolytes: Do not dissociate, so the solution remains non-conductive.

Water's polarity is key to its ability to aid in dissociation. It can stabilize ions in the solution, making it an excellent solvent for many substances. Understanding this process is fundamental to chemistry and many biological processes, aiding in the management of ionic balance.