Question

What is meant by a strong electrolyte? Give two examples of substances that behave in solution as strong electrolytes.

Short answer

A strong electrolyte is a solute that completely dissociates or ionizes into its ions when dissolved in a solvent, typically water. They have high solubility in water, fully ionize in an aqueous solution, and are ionic compounds or strong acids and bases. Strong electrolytes exhibit good electrical conductivity due to the presence of free ions in the solution. Two examples of strong electrolytes are sodium chloride (NaCl) and hydrochloric acid (HCl). The dissociation reactions in an aqueous solution for these substances are: \[NaCl_{(s)} \rightarrow Na^+_{(aq)} + Cl^-_{(aq)}\] \[HCl_{(g)} \rightarrow H^+_{(aq)} + Cl^-_{(aq)}\]

Step-by-step solution

Definition of Strong Electrolyte

A strong electrolyte is a solute that completely dissociates or ionizes into its ions when dissolved in a solvent, typically water. In solutions with strong electrolytes, the electrical conductivity is very high due to the presence of a large amount of free-moving ions. This results in a stronger flow of electric current in the solution.

Properties of Strong Electrolytes

Some characteristics of strong electrolytes are: - They have high solubility in water. - They fully ionize in an aqueous solution, meaning that none or very little of the undissociated solute is present. - They are ionic compounds or strong acids and bases. - They exhibit good electrical conductivity due to the presence of free ions in the solution.

Example 1: Sodium Chloride (NaCl)

Sodium chloride (NaCl) is an example of a strong electrolyte. It is an ionic compound and, when dissolved in water, it dissociates fully into sodium (Na⁺) and chloride (Cl⁻) ions. The dissociation reaction in an aqueous solution is: \[NaCl_{(s)} \rightarrow Na^+_{(aq)} + Cl^-_{(aq)}\] This complete dissociation allows the solution to conduct electricity efficiently due to the presence of free ions.

Example 2: Hydrochloric Acid (HCl)

Hydrochloric acid (HCl) is another example of a strong electrolyte. Being a strong acid, it fully ionizes when dissolved in water, producing hydrogen (H⁺) and chloride (Cl⁻) ions. The dissociation reaction in the aqueous solution is: \[HCl_{(g)} \rightarrow H^+_{(aq)} + Cl^-_{(aq)}\] In this case, the solution exhibits good electrical conductivity due to the presence of a large number of hydrogen and chloride ions that are free to move and participate in the conduction of electricity.

Key concepts

Ionization

Ionization is a fundamental process in which a molecule or compound splits into its constituent ions. When a substance ionizes, it forms charged particles that can conduct electricity in a solution.

• This process is particularly important for understanding how strong electrolytes work.
• For instance, when table salt (NaCl) dissolves in water, it breaks down into sodium ions (Na⁺) and chloride ions (Cl⁻).
• The ease with which a compound ionizes determines whether it is a strong or weak electrolyte.

In the case of strong electrolytes, the process of ionization is complete, meaning very few to no original molecules remain intact in the solution. This ability to fully break down into ions results in increased electrical conductivity.

Electrical Conductivity

Electrical conductivity, in the context of solutions, refers to the ability of the solution to carry an electric current. This property is largely dependent on the presence of ions in the solution.

• Solutions with a high concentration of free ions can conduct electricity well.
• Strong electrolytes, due to their full ionization, show excellent conductivity.
• Measuring a solution's ability to conduct electricity can indicate the presence and concentration of ions.

Therefore, strong electrolytes are particularly important in various applications, from batteries to biological systems, where efficient electrical conductivity is vital.

Ionic Compounds

Ionic compounds are chemical compounds composed of ions held together by electrostatic forces termed ionic bonds. These compounds usually consist of a metal and a non-metal.

• In a solid state, ionic compounds are typically structured in regular lattice arrangements.
• They dissolve in water, disassociating into cations and anions.
• The ions formed are crucial for the solution's electrical conductivity.

Sodium chloride (NaCl) is a classic example of an ionic compound. Its properties, like high melting and boiling points, and the ability to conduct electricity when molten or in solution, stem from the strong ionic bonds.

Hydrochloric Acid

Hydrochloric acid (HCl) is a strong acid known for its full ionization in water. This property makes it a prime example of a strong electrolyte.

• Upon dissolving in water, it dissociates completely into hydrogen (H⁺) and chloride (Cl⁻) ions.
• Its high acidity and ionization potential allow it to efficiently conduct electricity.
• HCl is used industrially and in laboratories, valued for its reactivity and strong acidic nature.

The presence of a large number of ions renders HCl solutions highly conductive, making them useful in various fields, from industrial etching to pH regulation.

Sodium Chloride

Sodium chloride, commonly known as table salt, is an excellent representative of strong electrolytes. It is an ionic compound that dissociates fully in solution.

• In an aqueous solution, its dissolution can be seen in the reaction: \[NaCl_{(s)} \rightarrow Na^+_{(aq)} + Cl^-_{(aq)}\]
• This complete breakdown into separate ions allows for high electrical conductivity.
• NaCl's properties make it essential in different contexts, such as food preservation, seasoning, and as a component in IV solutions.

By understanding the behavior of sodium chloride in solution, one can better appreciate how its ionic nature influences its function as a strong electrolyte.