The following aqueous solutions were tested with a light bulb conductivity apparatus, as shown in Figure 4.3. What result—dark, dim, or bright—do you expect from each? (a) 0.10 M hydrofluoric acid (b) 0.10 M sodium chloride (c) 0.10 M glucose (C6H12O6)

Verified step by step guidance

1. Identify the type of each compound: (a) hydrofluoric acid (HF) is a weak acid, (b) sodium chloride (NaCl) is a strong electrolyte, and (c) glucose (C6H12O6) is a non-electrolyte.
2. Understand the relationship between the type of compound and its conductivity: strong electrolytes fully dissociate in water, weak electrolytes partially dissociate, and non-electrolytes do not dissociate.
3. Predict the conductivity for each solution: (a) HF will produce a dim light because it partially dissociates, (b) NaCl will produce a bright light because it fully dissociates, and (c) glucose will produce a dark light because it does not dissociate.
4. Consider the concentration of each solution: all solutions are 0.10 M, which means the concentration is the same, so the differences in conductivity are due to the nature of the solute.
5. Summarize the expected results: (a) dim light for HF, (b) bright light for NaCl, and (c) dark light for glucose.

Key Concepts

Electrolytes and Nonelectrolytes

Electrolytes are substances that dissociate into ions when dissolved in water, allowing the solution to conduct electricity. Strong electrolytes, like sodium chloride, fully dissociate into ions, while weak electrolytes, such as hydrofluoric acid, only partially dissociate. Nonelectrolytes, like glucose, do not produce ions in solution and therefore do not conduct electricity.

Conductivity in Solutions

The conductivity of a solution is determined by the presence and concentration of ions. A bright light bulb indicates a high concentration of ions, resulting in strong conductivity, while a dim light suggests fewer ions. A dark result means no significant ion presence, indicating poor or no conductivity.

Concentration and Ionization

The concentration of a solute affects the number of ions available for conductivity. In the case of 0.10 M solutions, the degree of ionization is crucial; strong electrolytes like sodium chloride will fully ionize, while weak acids like hydrofluoric acid will only partially ionize, leading to different conductivity outcomes. Glucose, being a nonelectrolyte, will not contribute to conductivity regardless of its concentration.