Problem 17 - Chemistry and Chemical Reactivity

Question

What is an electrolyte? How can you differentiate experimentally between a weak electrolyte and a strong electrolyte? Give an example of each.

Step-by-Step Solution

Answer

An electrolyte conducts electricity in solution. Strong electrolytes fully dissociate, weak ones do not. NaCl is strong; acetic acid is weak.

Step 1: Understanding Electrolytes

An electrolyte is a substance that dissociates into ions when dissolved in water, allowing the solution to conduct electricity. Electrolytes include acids, bases, and salts.

Step 2: Differentiating Electrolytes Experimentally

To differentiate between a strong and a weak electrolyte experimentally, you can measure the electrical conductivity of their aqueous solutions. Strong electrolytes fully dissociate into ions and thus have high conductivity, while weak electrolytes partially dissociate and have lower conductivity.

Step 3: Example of a Strong Electrolyte

Sodium chloride (NaCl) is an example of a strong electrolyte. In aqueous solution, it fully dissociates into sodium \( Na^+ \) and chloride \( Cl^- \) ions, resulting in high conductivity.

Step 4: Example of a Weak Electrolyte

Acetic acid (CH₃COOH) is an example of a weak electrolyte. In aqueous solution, it only partially dissociates into acetate \( CH_3COO^- \) and hydrogen \( H^+ \) ions, resulting in lower conductivity compared to strong electrolytes.

Key Concepts

Strong Electrolytes

Strong electrolytes are substances that completely dissociate into ions when dissolved in water. This means that in aqueous solutions, they break apart fully to form freely moving ions which can conduct electricity efficiently. The full dissociation provides a clear path for electrical current, making these solutions perfect for applications needing high conductivity.

Common examples of strong electrolytes include:

• Sodium chloride (NaCl), which dissociates into sodium \( Na^+ \) and chloride \( Cl^- \) ions.
• Hydrochloric acid (HCl), which dissociates into hydrogen \( H^+ \) and chloride \( Cl^- \) ions.
• Sulfuric acid \((H_2SO_4)\), which dissociates into hydrogen \( H^+ \) and sulfate \( SO_4^{2-} \) ions.

These substances provide high electrical conductivity in their respective solutions, an important property for various chemical and industrial processes.

Measuring conductivity is one method to identify strong electrolytes, as they typically show a high conductivity reading due to the complete dissociation of ions in solution.

Weak Electrolytes

Weak electrolytes only partially dissociate into ions in solution. This incomplete dissociation results in fewer ions available to carry electrical current, leading to lower electrical conductivity when compared to strong electrolytes. As such, weak electrolytes somewhat "struggle" to conduct electricity due to the limited formation of ions.

Examples of weak electrolytes include:

• Acetic acid (CH₃COOH), which partially dissociates into acetate \( CH_3COO^- \) and hydrogen \( H^+ \) ions.
• Ammonium hydroxide \((NH_4OH)\), which partially dissociates into ammonium \( NH_4^+ \) and hydroxide \( OH^- \) ions.
• Carbonic acid \((H_2CO_3)\), known to dissociate slightly to hydrogen \( H^+ \) and bicarbonate \( HCO_3^- \) ions.

Such weak electrolytes do not provide the same level of conductivity as strong electrolytes, making them less suitable for applications requiring high electrical flow.

Electrical Conductivity

Electrical conductivity refers to the ability of a solution to conduct electricity, usually by allowing the flow of ions. Solutions with a high concentration of ions typically conduct electricity better than those with fewer ions.

Conductivity is measured using instruments known as conductivity meters, which provide a reading based on the ease with which electricity can pass through the solution. This property is crucial in determining whether a substance is a strong or weak electrolyte.

Factors affecting electrical conductivity include:

• The concentration of ions: More ions results in higher conductivity.
• The temperature of the solution: Higher temperatures can increase conductivity by providing more energy for ion movement.
• The type of ions: Some ions carry more charge or move more easily, affecting conductivity.

Understanding electrical conductivity is essential in fields like chemistry and environmental science, where monitoring ionic solutions is critical.