Speed of Dissolving
To demonstrate how water temperature affects the dissolving of sugar in liquid.
Theory & Background
Have you ever wondered about this fascinating scientific process? Everything in this universe is made of particles which are in constant motion. In a solid state particles move the slowest (the least), while in a liquid state particles move at their fastest (the most). Under the right conditions, solids particles (the solute) inter-mixed with liquid particles (the solvent) can form a "solution". This occurrence is known as dissolving.
Required Materials
- Sugar
- 3 glasses of the same size
- Water
- Spoon
- Pen
- Notebook or journal (to record your results)
Estimated Time
About 30 minutes
Step-By-Step Procedure
Fill one glass about two-thirds full with cold water from the refrigerator. The water should be icy-cold to the touch.
Add two heaping teaspoons of sugar to the glass and stir with the spoon. Keep stirring until the sugar dissolves, making sure to note the time it takes for it to dissolve (either count or use a stop-watch). Write the results in your journal.
Fill another cup about two-thirds full with warm water from the faucet. Make sure the water is neither hot nor cold. It should be room temperature or slightly warm.
Once again add two heaping teaspoons of sugar into the glass with warm water and stir with the spoon. Stir until the sugar dissolves, making sure to note the time it takes to dissolve in your journal.
Boil some water and pour it into the last glass so that it's two-thirds full.
Once again follow the steps of putting in two heaping teaspoons of sugar, stirring, and notating the amount of time it takes the sugar to dissolve.
What did you discover about the rate of dissolving?
Experiment Tips
- Be very careful when boiling the water! You may need the assistance of an adult before handling hot liquid. Also keep in mind that the glass you pour the boiling water into WILL be very hot! Take the necessary precautions to avoid injury.
Observation
Which of the glasses dissolved the sugar the fastest? Can you explain why the sugar dissolved the fastest? Do you think you would get the same results if you tried to dissolve something other than sugar, such as salt?
Result & Conclusion
The warmer the water, the faster the particles are moving around. This means the faster the water and sugar particles will mix together, so the boiling water should have dissolved the sugar fastest. The cooled water should have dissolved the sugar the slowest because the particles will be moving around much more slowly.