Question

Identify each of the following compounds as a nonelectrolyte, a weak electrolyte, or a strong electrolyte: (a) lactose \(\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\right),(\mathrm{b})\) lactic acid \(\left(\mathrm{HC}_{3} \mathrm{H}_{5} \mathrm{O}_{3}\right),\) (c) dimethylamine \(\left[\left(\mathrm{CH}_{3}\right)_{2} \mathrm{NH}\right]\), (d) barium hydroxide \(\left[\mathrm{Ba}(\mathrm{OH})_{2}\right]\)

Short answer

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

Step-by-step solution

Understanding Electrolytes

Compounds are classified into three types based on their ability to conduct electricity when dissolved in water: nonelectrolytes, which do not conduct electricity, weak electrolytes, which partially ionize and partially conduct electricity, and strong electrolytes, which completely ionize and conduct electricity efficiently.

Analyze Lactose

Lactose is a sugar with the molecular formula \(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\). Sugars are covalent compounds that do not ionize in solution, making them nonelectrolytes.

Analyze Lactic Acid

Lactic acid \(\left(\mathrm{HC}_{3} \mathrm{H}_{5} \mathrm{O}_{3}\right)\) is a weak acid. Weak acids partially ionize in water; thus, lactic acid is a weak electrolyte.

Analyze Dimethylamine

Dimethylamine \(\left[\left(\mathrm{CH}_{3}\right)_{2} \mathrm{NH}\right]\) is a weak base. Similar to weak acids, weak bases partially ionize in solution, classifying dimethylamine as a weak electrolyte.

Analyze Barium Hydroxide

Barium hydroxide \(\left[\mathrm{Ba}( ext{OH})_{2}\right]\) is a strong base which fully dissociates into barium ions and hydroxide ions in solution, making it a strong electrolyte.

Key concepts

Nonelectrolyte

Nonelectrolytes are substances that do not produce ions or electric currents when dissolved in water. Simply put, they do not conduct electricity in a solution. These compounds typically consist of molecules without charge, such as sugars and many types of organic compounds.
For instance, lactose, with the formula \(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\), is a nonelectrolyte. Even when dissolved, lactose doesn't break into ions. It remains as whole, neutral molecules in the solution.

• Examples: Sugar, Ethanol, Urea
• Does not ionize or dissociate in water
• Cannot conduct electricity in solution

Weak Electrolyte

Weak electrolytes are compounds that partially ionize in solution. They exist in a state of equilibrium between the ionized and non-ionized forms. This partial ionization means they only partially conduct electricity.
Taking lactic acid, \(\mathrm{HC}_{3} \mathrm{H}_{5} \mathrm{O}_{3} \), as an example, in solution, it does not completely break into its ions. This quality makes it a weak electrolyte.

• Partially ionizes in water
• Weak acids and bases are common examples
• Conducts electricity poorly compared to strong electrolytes

Strong Electrolyte

Strong electrolytes are substances that fully ionize or dissociate in solution. They break down completely into ions, ensuring efficient electrical conduction.
A strong base like barium hydroxide \( \mathrm{Ba(OH)}_{2} \) is a strong electrolyte. In water, it dissociates entirely into barium \( \mathrm{Ba}^{2+} \) and hydroxide ions \( \mathrm{OH}^{-} \), allowing for excellent electrical conductivity.

• Completely ionizes in solution
• Includes most salts, strong acids, and strong bases
• Conducts electricity very efficiently

Dissociation

Dissociation refers to the process where ionic compounds separate into positive and negative ions. This process is crucial for substances to act as electrolytes in solution.
Dissociation occurs in strong electrolytes like barium hydroxide, \( \mathrm{Ba(OH)}_{2} \), where the compound splits into \( \mathrm{Ba}^{2+} \) and \( \mathrm{OH}^{-} \) ions.

• Applies mainly to ionic compounds
• Drives the conductivity in strong electrolytes
• Complete dissociation results in full electrical conduction

Ionization

Ionization is the process by which a neutral molecule produces charged ions. It is particularly relevant for acids and bases that do not naturally exist as ions. Unlike dissociation, which involves already-ionic substances, ionization can turn neutral molecules into ions.
Consider dimethylamine \(\left[\left(\mathrm{CH}_{3}\right)_{2} \mathrm{NH}\right]\), which ionizes weakly in water. It forms a small number of \(\mathrm{CH}_{3}\) and \(\mathrm{NH}^{+}\) ions, qualifying it as a weak electrolyte.

• Relates to the formation of ions from neutral molecules
• Important for acids and bases
• Weak ionization leads to weak electrical conduction