Solubility curve is a plot of solubility against

Analysis

The question asks for the definition of a solubility curve. To answer this, we need to understand how the solubility of a substance (usually a solid) changes in relation to external conditions.

Concept Explanation

A solubility curve is a graphical representation used in chemistry to show the relationship between the solubility of a solute and a specific variable.

For most solid solutes in a liquid solvent (like water), solubility is highly dependent on temperature. As the temperature of the solvent increases, the kinetic energy of the molecules increases, which generally allows more solute to dissolve. By plotting the mass of the solute that can dissolve in 100g of water (solubility) on the y-axis against the temperature on the x-axis, we create a curve that helps us determine how much of a substance will dissolve at any given temperature.

Step-by-Step Solution

1. Identify the variables: Solubility is defined as the maximum amount of solute that can dissolve in a given amount of solvent at a specific temperature.
2. Evaluate the options: • Pressure: While pressure significantly affects the solubility of gases (Henry's Law), it has a negligible effect on the solubility of most solids and liquids. Solubility curves are primarily used for solids. • Volume: Volume is a measure of the amount of solvent, not a factor that changes the solubility limit of a substance. • Concentrate: Concentration is a measure of how much solute is already dissolved; it is not the independent variable plotted against solubility. • Temperature: This is the primary factor that dictates how much solute can be held in a saturated solution.
3. Conclusion: Since the solubility of solids changes predictably with temperature, the graph of solubility versus temperature is the standard "solubility curve."

Correct Answer

The correct option is A.

Exam Tip

When you see "Solubility Curve" in your JAMB exam, immediately think of a Temperature-Solubility graph. If the curve goes upward, it shows that the substance's solubility increases as the temperature rises (which is true for most salts like Potassium Nitrate). If the curve is flat, the solubility is barely affected by temperature (like Sodium Chloride).