Question

For each compound (all water soluble), would you expect the resulting aqueous solution to conduct clectrical current? a. \(\mathrm{Cs} \mathrm{cl} \quad\) b. \(\mathrm{CH}_{3} \mathrm{OH} \quad\) c. \(\mathrm{Ca}\left(\mathrm{NO}_{2}\right)_{2} \quad\) d. \(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\)

Short answer

CsCl and Ca(NO2)2 solutions will conduct electricity; CH3OH will conduct very little; C6H12O6 will not conduct electricity.

Step-by-step solution

Identify the Type of Each Compound

To determine if a solution conducts electricity, identify if the compound is an electrolyte. Electrolytes dissociate into ions in water, allowing the solution to conduct electricity. Ionic compounds and some polar covalent compounds are electrolytes. CsCl is an ionic compound, while CH3OH (methanol) and C6H12O6 (glucose) are covalent compounds. Ca(NO2)2 is ionic with two polyatomic ions.

Assess the Dissociation of Each Compound in Water

Ionic compounds like CsCl and Ca(NO2)2 will dissociate into ions in water. Covalent compounds like CH3OH can have polarity and thus may still conduct electricity if they can ionize or if they are polar enough to allow charge movement, although to a much lesser degree than ionic compounds. However, C6H12O6 is a sugar and does not ionize or conduct electricity in solution.

Determine the Conductivity of Solutions

CsCl and Ca(NO2)2 will dissociate fully into ions and will conduct electricity well as strong electrolytes. CH3OH will conduct very little as a weak electrolyte, and C6H12O6 will not conduct electricity as it does not provide ions in solution.

Key concepts

Electrolytes

Electrolytes are substances that can conduct electricity when dissolved in water. They are critical in many processes, both industrially and biologically, for their ability to allow the flow of electrical currents. Electrolytes are typically salts, acids, and bases that dissociate into their respective ions in an aqueous solution.

The conductivity of an electrolyte solution is due to the presence of these free ions which are charged particles. When an electrical potential is applied, these ions move towards the oppositely charged electrode, creating an electric current. Strong electrolytes, like common table salt (NaCl), dissociate completely in water, giving a high concentration of ions and thus, high conductivity. Weak electrolytes, such as acetic acid (vinegar), only partially dissociate, providing fewer ions and lower conductivity.

Understanding electrolytes is essential in explaining the electrical properties of various solutions, crucial for students studying chemistry or engaged in fields requiring such knowledge.

Ionic and Covalent Compounds

Knowing the difference between ionic and covalent compounds helps us predict whether a substance will conduct electricity when dissolved in water. Ionic compounds are formed from the electrostatic attraction between cations and anions. In a solution, these compounds typically dissociate into their individual ions. Examples include sodium chloride (NaCl) and calcium nitrite (Ca(NO2)2).

On the other hand, covalent compounds are formed when atoms share electrons, resulting in molecules with no overall charge. Methanol (CH3OH) and glucose (C6H12O6) are examples of covalent compounds. They do not dissociate into ions in solution; thus, they usually exhibit low to no conductivity. However, some polar covalent molecules can conduct a small electric current due to their polarity-induced partial charges, which may allow for some degree of charge movement.

Dissociation of Compounds

Dissociation is the process in which a compound breaks apart into its constituent ions when dissolved in water. The degree to which a compound dissociates is a key factor in determining the conductivity of its aqueous solution.

For example, ionic compounds such as CsCl (cesium chloride) and Ca(NO2)2 (calcium nitrite) dissociate almost completely in solution, producing a high number of ions that can move freely and conduct electricity. This makes them strong electrolytes. Contrastingly, many covalent compounds do not dissociate in water. Substances like glucose (C6H12O6), despite being soluble in water, remain as whole molecules and do not provide ions for conducting electricity, rendering them non-electrolytes. Methanol (CH3OH) partially dissociates, which means it can conduct electricity to some extent, classifying it as a weak electrolyte.

Understanding the concept of dissociation empowers students with the ability to predict the electrical behavior of various substances in an aqueous solution, an important skill in chemistry and related scientific studies.