You're getting at the concept of solubility, which is the maximum amount of a solute (like KNO3) that can dissolve in a given amount of solvent (like water) at a specific temperature.

Here's why a 100 ml solution of KNO3 can't hold more than 37 g at a certain temperature:

* Saturated Solution: When you reach the solubility limit, the solution is called saturated. At this point, no more solute can dissolve. Any additional KNO3 added will simply settle at the bottom.

* Dynamic Equilibrium: In a saturated solution, the rate of dissolving KNO3 molecules equals the rate of KNO3 molecules crystallizing out of the solution. This creates a dynamic equilibrium.

* Factors Affecting Solubility:

* Temperature: The solubility of most solids, including KNO3, increases as temperature rises. This means you can dissolve more KNO3 in hot water than in cold water.

* Nature of Solute and Solvent: The chemical properties of the solute and solvent play a crucial role in determining solubility.

* Pressure: While pressure has little effect on the solubility of solids in liquids, it significantly impacts gases.

Example:

At room temperature (around 25°C), the solubility of KNO3 in water is about 37 g per 100 ml. If you try to dissolve more than 37 g of KNO3 in 100 ml of water, the excess KNO3 will remain undissolved.

Important Note: The exact solubility of KNO3 at different temperatures is important to consider. For precise calculations, you can look up the solubility data in a reference book or online database.