Question

Classify the following compounds as electrolytes or nonelectrolytes. (a) potassium chloride, \(\mathrm{KCl}\) (b) hydrogen peroxide, \(\mathrm{H}_{2} \mathrm{O}_{2}\) (c) methane, \(\mathrm{CH}_{4}\) (d) barium nitrate, \(\mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}\)

Short answer

Question: Classify the following compounds as electrolytes or nonelectrolytes: Potassium chloride (KCl), Hydrogen peroxide (H2O2), Methane (CH4), and Barium nitrate (Ba(NO3)2). Answer: Potassium chloride (KCl) is an electrolyte. Hydrogen peroxide (H2O2) and Methane (CH4) are nonelectrolytes. Barium nitrate (Ba(NO3)2) is an electrolyte.

Step-by-step solution

1. Potassium chloride, \(\mathrm{KCl}\)

Potassium chloride consists of ions: one potassium ion (\(\mathrm{K}^{+}\)) and one chloride ion (\(\mathrm{Cl}^{-}\)). When potassium chloride dissolves in water, it dissociates into these ions, making it an electrolyte, as ions are able to conduct electricity.

2. Hydrogen peroxide, \(\mathrm{H}_{2} \mathrm{O}_{2}\)

Hydrogen peroxide is a covalent compound that consists of two hydrogen atoms and two oxygen atoms bonded together, forming a molecule. When hydrogen peroxide dissolves in water, it does not dissociate into ions. Therefore, it is a nonelectrolyte, unable to conduct electricity.

3. Methane, \(\mathrm{CH}_{4}\)

Methane is an organic compound formed by one carbon atom bonded to four hydrogen atoms, creating a covalent molecule. In water, methane does not dissolve or dissociate into ions. Consequently, methane is classified as a nonelectrolyte, since it cannot conduct electricity.

4. Barium nitrate, \(\mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}\)

Barium nitrate is an ionic compound consisting of a barium ion (\(\mathrm{Ba}^{2+}\)) and two nitrate ions (\(\mathrm{NO}_{3}^{-}\)). When dissolved in water, barium nitrate dissociates into its respective ions, thus being an electrolyte, as these ions can conduct electricity.

Key concepts

Ionic and Covalent Compounds

Understanding the difference between ionic and covalent compounds is fundamental in chemistry.

Ionic compounds are formed when metals transfer electrons to nonmetals, resulting in positively charged ions, known as cations (such as \(\mathrm{K}^{+}\) from potassium), and negatively charged ions, known as anions (such as \(\mathrm{Cl}^{-}\) from chlorine). This electron transfer leads to the electrostatic attraction between ions, binding them together in a crystal lattice structure. Common examples include sodium chloride (table salt) and barium nitrate.

Covalent compounds, on the other hand, occur when two nonmetals share electrons, creating a bond. Molecules like hydrogen peroxide (\(\mathrm{H}_{2} \mathrm{O}_{2}\)) and methane (\(\mathrm{CH}_{4}\)) are prime examples of covalent bonding, where atoms are held together by shared pairs of electrons in a more discrete molecular form.

Understanding the nature of these chemical bonds aids in predicting how these compounds will interact with water and whether they can conduct electricity when dissolved.

Dissociation in Water

Dissociation in water is a process that involves the separation of molecules or ionic compounds into smaller particles, such as ions. This occurs when a substance is soluble in water.

Ionic compounds display a notable tendency to dissociate in water, given that water is a polar solvent. For instance, when potassium chloride (\(\mathrm{KCl}\)) is dissolved in water, it separates into potassium ions (\(\mathrm{K}^{+}\)) and chloride ions (\(\mathrm{Cl}^{-}\)).

In contrast, covalent compounds do not generally dissociate into ions in water; rather, they dissolve as whole molecules if they are polar and water-soluble, like sugar or hydrogen peroxide (\(\mathrm{H}_{2} \mathrm{O}_{2}\)). Nonpolar molecules like methane (\(\mathrm{CH}_{4}\)) are largely insoluble in water and do not dissociate or dissolve to any significant extent.

The extent of dissociation is crucial for the electrical conductivity of the solution, which relies on the presence and mobility of ions.

Electrical Conductivity in Solutions

Electrical conductivity in solutions is closely linked to the presence of free-floating ions that are capable of carrying electrical current.

Electrolytes are substances that produce ions when dissolved in water, thus allowing the solution to conduct electricity. For instance, the dissociation of potassium chloride (\(\mathrm{KCl}\)) in water produces \(\mathrm{K}^{+}\) and \(\mathrm{Cl}^{-}\) ions, which can move freely in the solution and carry charge, making it an electrolyte. Similarly, barium nitrate (\(\mathrm{Ba}(\mathrm{NO}_{3})_{2}\)) dissolves to release \(\mathrm{Ba}^{2+}\) and \(\mathrm{NO}_{3}^{-}\) ions that also confer electrolytic properties to the solution.

Nonelectrolytes, such as hydrogen peroxide (\(\mathrm{H}_{2} \mathrm{O}_{2}\)) and methane (\(\mathrm{CH}_{4}\)), either do not dissolve in water or do not produce ions when they do. Thus, their solutions lack the charged particles necessary for electrical conductivity. This fundamental characteristic of electrolytes and nonelectrolytes plays a significant role in various chemical applications, from biological systems to industrial processes.