According to the provided reference, the solubility value of a substance is determined by finding the maximum concentration of the solute in a solution where some of the solute remains undissolved, known as a saturated solution.
Understanding Solubility
Solubility is a fundamental property of a substance, defining the maximum amount of a solute that can dissolve in a given amount of solvent at a specific temperature and pressure. This crucial value indicates the point at which the solution becomes saturated and can no longer dissolve additional solute.
The Method for Determining Solubility
Based on the reference, the practical method for determining solubility involves a step-by-step process to achieve a saturated solution:
- Start with the Solvent: Begin with a known quantity of the solvent (e.g., water).
- Add Solute Incrementally: Gradually add small amounts (increments) of the solute to the solvent.
- Dissolution: Allow the solute to dissolve, stirring or agitating as necessary.
- Observe for Undissolved Solute: Continue adding increments of the solute until you observe that some of the solute no longer dissolves and remains as a solid precipitate at the bottom or dispersed in the solution.
- Achieve Saturation: At this point, the solution is considered saturated. This means the solvent has dissolved the maximum possible amount of solute under the given conditions.
- Analyze Concentration: To determine the solubility value, you then analyze the concentration of the solute that is dissolved in this saturated solution. The concentration measured at this stage represents the maximum soluble quantity.
- The reference explicitly states: "Solubility can only be determined by adding increments of the solute until it no longer dissolves. Analyzing the concentration of the solute in a SATURATED solution (where some of the solute is undissolved) WILL give you an accurate value for the solubility, as it will be the maximum soluble quantity."
Why This Method Works
This method ensures you are measuring the true limit of dissolution. By ensuring there is some undissolved solute present, you guarantee that the solution is indeed saturated, and the concentration of the dissolved solute is at its maximum possible value for those specific conditions (temperature, pressure, and the specific solvent). Measuring the concentration in a non-saturated solution would give a value lower than the actual solubility.
