Supersaturated Solutions and Crystallization

Ronn Fieldhouse, a Chemistry Curriculum Specialist at PASCO scientific, explains and demonstrates a supersaturated solution. He defines it as a solution containing more solute than can be dissolved under normal conditions. Using sodium acetate trihydrate, he creates a supersaturated solution and demonstrates how adding a crystal initiates crystallization, causing a temperature change. The process illustrates the conservation of energy, as the energy used to dissolve the solute is released during crystallization.

What is a supersaturated solution?

• A solution that is completely stable and permanent.

• A solution with less solute than it can hold at a given temperature.

• A solution that cannot dissolve any solute.

• A solution with more solute than it can hold under set conditions.

How much sodium acetate trihydrate was used to create the supersaturated solution?

• 50 g

• 100 g

• 25 g

• 10 g

What is the role of the crystal added to the supersaturated solution?

• It dissolves completely.

• It changes the color of the solution.

• It stabilizes the solution.

• It initiates crystallization.

What happens to the temperature of the solution when crystallization begins?

• It decreases significantly.

• It fluctuates randomly.

• It remains constant.

• It increases.

Why should the solution not be boiled during the preparation?

• Boiling degrades the acetate.

• Boiling makes the solution too thick.

• Boiling causes the solution to evaporate completely.

• Boiling makes the solution too cold.

What is the initial temperature reading of the solution before crystallization?

• 30.4 degrees

• 40.4 degrees

• 25.4 degrees

• 35.4 degrees

What should be avoided to maintain the stability of the supersaturated solution before crystallization?

• Adding more solute

• Adding more solvent

• Shaking or bumping the container

• Heating the solution

What is the significance of the temperature probe in the demonstration?

• It adds heat to the solution.

• It measures the temperature changes.

• It stabilizes the solution.

• It prevents crystallization.

What concept does the supersaturated solution demonstration also illustrate?

• Conservation of charge

• Conservation of momentum

• Conservation of energy

• Conservation of mass

What is the final temperature change observed during the demonstration?

• 5 degrees

• 10 degrees

• 20 degrees

• 15 degrees