This demonstration shows how the size of solid particles affects the rate at which they dissolve. By comparing the dissolving times of crushed and uncrushed table salt in water, students can observe that smaller particles dissolve faster due to greater surface area contact with the solvent.

1. Prepare two equal amounts of table salt (about one teaspoon each).
2. Leave one sample as uncrushed salt crystals.
3. Crush the second sample into smaller particles using a mortar and pestle or the back of a spoon.
4. Pour equal amounts of warm water (about 100 mL) into two clear glasses or beakers.
5. Add the uncrushed salt to one glass and the crushed salt to the other at the same time.
6. Stir both solutions gently and observe which sample dissolves faster.
7. Record observations and note the time taken for each sample to dissolve completely.

The Effect of Particle Size on Solubility - Joedelyn Cruz:

Effect of particle size on dissolution of a substance in water - Learning Factory:

• Repeat the experiment with sugar or other soluble solids.
• Try using cold and hot water to observe how temperature affects solubility rate.
• Use different crushing degrees (fine powder vs coarse grains) to see how surface area impacts dissolving time.

• Handle glassware carefully to prevent breakage.
• Use warm, not boiling, water to avoid burns.
• Do not taste the solutions.
• Clean all equipment thoroughly after the experiment.

• Which sample dissolved faster—crushed or uncrushed salt? (Crushed salt.)
• Why did the crushed salt dissolve faster? (Smaller particles have a greater surface area exposed to water molecules.)
• Does particle size affect how much solute can dissolve in water? (No, only the rate of dissolving changes, not the total solubility.)
• What other factors besides particle size can affect dissolving rate? (Temperature, stirring, and solvent type.)