Problem 37 - Chemistry The Central Science

Question

Classify each of the following substances as a nonelectrolyte, weak electrolyte, or strong electrolyte in water: (a) \(\mathrm{H}_{2} \mathrm{SO}_{3}\) , (b) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}\) (ethanol), \((\mathbf{c}) \mathrm{NH}_{3},(\mathbf{d}) \mathrm{KClO}_{3}\), \((\mathbf{e}) \mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}\).

Step-by-Step Solution

Answer

In summary: a) \(H_2SO_3\) - weak electrolyte b) \(CH_3CH_2OH\) (Ethanol) - nonelectrolyte c) \(NH_3\) - weak electrolyte d) \(KClO_3\) - strong electrolyte e) \(Cu(NO_3)_2\) - strong electrolyte

Step 1: Classifying H2SO3

Sulfurous acid (H2SO3) is a weak acid, which means it will partially ionize in water. Thus, H2SO3 is a weak electrolyte.

Step 2: Classifying CH3CH2OH (Ethanol)

Ethanol (CH3CH2OH) is an organic compound that is soluble in water but does not dissociate into ions. Therefore, ethanol is a nonelectrolyte.

Step 3: Classifying NH3 (Ammonia)

Ammonia (NH3) is a weak base that partially ionizes in water to form hydroxide ions (OH-) and ammonium ions (NH4+). Since it does not ionize completely, NH3 is a weak electrolyte.

Step 4: Classifying KClO3 (Potassium Chlorate)

Potassium Chlorate (KClO3) is an ionic compound that completely dissociates into potassium (K+) and chlorate ions (ClO3-) when dissolved in water. As a result, KClO3 is a strong electrolyte.

Step 5: Classifying Cu(NO3)2 (Copper(II) Nitrate)

Copper(II) Nitrate (Cu(NO3)2) is an ionic compound that fully dissociates into copper (Cu2+) and nitrate ions (NO3-) when dissolved in water. This makes Cu(NO3)2 a strong electrolyte. #Summary#: In summary, the given substances can be classified into nonelectrolytes, weak electrolytes, or strong electrolytes as follows: a) H2SO3 - weak electrolyte b) CH3CH2OH (Ethanol) - nonelectrolyte c) NH3 - weak electrolyte d) KClO3 - strong electrolyte e) Cu(NO3)2 - strong electrolyte

Key Concepts

Nonelectrolyte

A nonelectrolyte is a substance that does not produce ions when dissolved in water. Consequently, it does not conduct electricity. An example of this is ethanol ((CH3CH2OH)), an organic compound with polar molecules that dissolve in water but maintain their molecular integrity without generating ions. In the classroom, students can visualize nonelectrolytes by imagining the substance dissolving like sugar or urea in water; they spread out but do not break into charged particles.

Weak Electrolyte

A weak electrolyte is a substance that only partially dissociates into ions when dissolved in water. As a result, it conducts electricity, but not as well as a strong electrolyte. Sulfurous acid (H2SO3) and ammonia (NH3) are typical examples of weak electrolytes. They create an equilibrium state where both the undissociated molecule and the ions coexist in solution. For learners, it's helpful to think of weak electrolytes as having a modest split personality—part of it breaks up into ions, while part stays intact.

Strong Electrolyte

A strong electrolyte, on the other hand, completely disassociates into ions in water. This means that it is an excellent conductor of electricity. Examples from our exercise include potassium chlorate (KClO3) and copper(II) nitrate (Cu(NO3)2). These ionic compounds break apart into their constituent ions when dissolved, resulting in a solution that contains no original molecular entities. Students can imagine this as dropping a cube of salt into water where it fragments completely into sodium and chloride ions.

Ionic Compounds

Ionic compounds are made up of positively and negatively charged ions held together by strong electrostatic forces known as ionic bonds. In the context of solubility, when these compounds are introduced to water, they typically disintegrate into their respective ions. This property is what renders substances such as KClO3 and Cu(NO3)2 strong electrolytes. The educational key here is that the complete dissociation of an ionic compound in water is synonymous with the substance being a strong electrolyte.

Dissociation in Water

Dissociation in water is a process in which ionic compounds separate into ions when they are dissolved in water. This can vary from a full separation in strong electrolytes to a partial separation in weak electrolytes. The extent and nature of this dissociation process are what determine whether a solution will conduct electricity well, poorly, or not at all. In teaching, this can be illustrated by showing animations or conducting experiments that visually demonstrate how different substances behave when dissolved in water.