Here's why:
* Qualitative vs. Quantitative: This method tells you *if* the solution is saturated (if the solid settles) or unsaturated (if it dissolves). It doesn't tell you *how* saturated the solution is.
* Solubility Dependence: Solubility of a solid in a liquid is affected by factors like temperature, pressure, and the specific nature of the solute and solvent. Just observing if the solid settles doesn't account for these variables.
A Better Approach:
To determine the degree of saturation, you need a more quantitative method. Here are some common techniques:
1. Solubility Tables/Graphs: Look up the solubility of your specific solute in your specific solvent at the relevant temperature. This will tell you the maximum amount of solute that can dissolve per unit of solvent.
2. Titration: This involves gradually adding a solution of known concentration (titrant) to a solution of unknown concentration (analyte) until a specific reaction endpoint is reached. This can be used to determine the concentration of the solute in the original solution.
3. Spectrophotometry: This technique measures the absorbance of light by a solution, which can be related to the concentration of the solute.
Example:
Let's say you're trying to determine the degree of saturation of a sugar solution. You add a spoonful of sugar, and it dissolves. This tells you the solution is unsaturated. However, you don't know how much more sugar you could add before it becomes saturated.
To determine the degree of saturation, you could use a solubility table to look up the maximum amount of sugar that dissolves in water at room temperature. This would give you a quantitative measure of how much sugar could still dissolve in the solution.
In summary: While adding a solid to a solution can give you a basic understanding of its saturation, a more precise approach requires quantitative methods like solubility tables, titration, or spectrophotometry.
