Name ______Date ______Period ______
Growing Crystals from Supersaturated Solutions
Pre Lab Questions:
1. What is the difference between an unsaturated, saturated and a supersaturated solution?
Unsaturated:______Saturated:______Supersaturated______
2. What is the solute in the lab? ______the solvent?______
3. Why is it necessary to heat a solvent in order to make a supersaturated solution?
______
4. Salts (ionic compounds) dissolve easily in water. Since “like dissolves like”, how do you explain the salt’s solubility in water?
______
Discussion Questions:
1. Besides increasing the temperature of the water, describe two ways you could get the salts to dissolve in water faster.
A.______
B.______
2. Describe a point in the lab where each of the following happened…
a. You had an unsaturated solution ______
b. You had a saturated solution ______
c. You had a supersaturated solution
______
Keep thinking together….
3. Talk with your group, and try to come up with one other method to create a supersaturated solution that does not involve heating. (How can you remove more solvent?)
______
4. You dissolved 450.0 g of sugar (C12H22O11) in 150 mL of water. The density of water is 1.00g/mL
a. calculate the molarity of the solution (moles of solute/ liters of solution) SHOW YOUR WORK!!!
b. calculate the molality of the solution (moles of solute/ kg of solvent) SHOW YOUR WORK!!!
Conclusion:
1. Describe how you created a supersaturated solution and how you formed borax crystals.
______
2. Describe the general shape of the crystals (are they round, jagged, smooth etc.), and how they compare to the salt crystals you started with.
______
3. Did any crystals form on places other than the string? Were any stuck to the jar? Explain how you think these problems could be avoided.
______
4. If you had the perfect crystal, then explain why you think yours turned out so much better and explain how you think you can make even larger crystals.
______