Question

Classify each of the following as a strong electrolyte or nonelectrolyte. (a) \(\mathrm{KCl}\) (b) \(\mathrm{C}_{3} \mathrm{H}_{5}(\mathrm{OH})_{3} \quad\) (glycerin) (c) \(\mathrm{NaOH}\) (d) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH} \quad\) (ethanol)

Short answer

(a) \(KCl\) is a strong electrolyte. (b) Glycerin is a nonelectrolyte. (c) \(NaOH\) is a strong electrolyte. (d) Ethanol is a nonelectrolyte.

Step-by-step solution

Understanding Strong Electrolytes

Strong electrolytes are compounds that completely dissociate into ions when dissolved in water, allowing the solution to conduct electricity efficiently. Common strong electrolytes include soluble salts, strong acids, and strong bases.

Classify \(KCl\)

\(KCl\) is a salt formed from a strong acid (\(HCl\)) and a strong base (\(KOH\)). Since it is a salt and dissociates completely in water, \(KCl\) is a strong electrolyte.

Classify \(C_{3}H_{5}(OH)_{3}\) (glycerin)

Glycerin is an organic compound with multiple \(OH\) groups and does not fully dissociate into ions in water. Therefore, it is classified as a nonelectrolyte.

Classify \(NaOH\)

\(NaOH\) is a strong base that completely dissociates into \(Na^+\) and \(OH^-\) ions in water. Hence, it is a strong electrolyte.

Classify \(CH_3CH_2OH\) (ethanol)

Ethanol is an alcohol that does not ionize in water, instead dissolving as whole molecules, and thus it is considered a nonelectrolyte.

Key concepts

Electrolyte Classification

Understanding the classification of electrolytes is crucial for grasping how different substances interact with water to either conduct electricity, or not. Electrolytes are substances that dissolve in water to produce charged particles called ions, which can move freely in solution. They are usually classified into two main categories: strong electrolytes and nonelectrolytes.

Strong electrolytes, such as KCl (potassium chloride) and NaOH (sodium hydroxide), completely ionize in water. This means that if you have 100 molecules of a strong electrolyte, all 100 would separate into ions in water. In contrast, nonelectrolytes do not ionize in water. Substances like glycerin (C₃H₅(OH)₃) and ethanol (CH₃CH₂OH) are nonelectrolytes because they dissolve as molecules without forming ions.

Electrolyte classification is not only important for chemistry but also for biology and medicine, as many bodily processes depend on the careful balance of electrolytes.

Dissociation in Water

Dissociation in water is the process through which ionic compounds separate into their respective positive and negative ions. This process is vital for understanding how conductivity occurs in solutions.

When strong electrolytes like KCl or NaOH are dissolved in water, they dissociate completely. For instance, common table salt (NaCl) will dissociate into Na⁺ and Cl^- ions. This full dissociation allows the solution to conduct an electrical current effectively.

On the other hand, nonelectrolytes enter the solution as whole molecules that do not bear a charge. Because these molecules do not break into ions, they cannot carry an electric current through the solution. The tendency of a substance to dissociate in water determines its classification as a strong or weak electrolyte, or as a nonelectrolyte.

Conductivity in Solution

Conductivity in a solution refers to the ability of the solution to carry an electric current. This property largely depends on the presence and mobility of ions in the solution.

In a solution with strong electrolytes, the abundance of ions provides a path for electricity to flow through the solution. For example, when KCl is dissolved in water, it creates K⁺ and Cl^- ions that move freely and allow for effective electric conduction.

Conversely, a solution with nonelectrolytes, such as glycerin or ethanol, shows poor conductivity because these substances do not release ions when dissolved in water. Thus, in practical terms, if you were to attach electrodes to a solution and observe no flow of electricity, you could infer that the solution likely contains nonelectrolytes.

Organic Compounds in Chemistry

Organic compounds are a vast group of molecules that contain carbon atoms, usually bonded to hydrogen, oxygen, or other carbon atoms. In the context of electrolytes, it's noteworthy that many organic compounds do not dissociate into ions and are typically nonelectrolytes.

Compounds like glycerin and ethanol are organic and do not ionize when dissolved in water. Despite the many OH (hydroxyl) groups that might suggest a capacity to ionize, glycerin remains non-ionic in solution. Similarly, although ethanol has a single OH group, which is characteristic of alcohols, it also does not ionize. This is primarily due to the stable nature of the covalent bonds holding the atoms together within these molecules.

In contrast, inorganic ionic compounds—salts, acids, and bases—often dissociate in water, resulting in solutions that conduct electricity well. The understanding of organic chemistry is vital for various scientific fields, including pharmaceuticals, materials science, and biochemistry.