Take Home Lab #1 spring semester

Take Home Lab #1:  Growing Crystals

Question: How are crystals of different crystals similar and different?

Safety: Do not eat any of the crystals or other materials during this activity, as mold quickly grows on some of the crystals. Mark the cups clearly and keep them out of the reach of children .Clean up spills immediately.

Materials: cups, water, sugar, salt, Epsom salt, thread

Procedure: In this lab, you will grow three different types of crystals: sugar, salt and Epsom salts. Crystals are grown by either dissolving more material than the solvent (the water) can normally hold by heating it, or by allowing the solvent to evaporate over time. In this procedure, you will do a little of both. You will put a lot of solute (the substance that dissolves) in a little solvent and heat it to dissolve; then you will let it sit for a few days to evaporate.

1. For each of the solutes (salt, sugar, Epsom salts), dissolve a large spoonful in 1 cup of boiling water in a glass cup.  (Be careful when boiling water please!) For sugar you will need to add 2-3 large spoonfuls of sugar to 1 cup of boiling water. Stir until all of the solute is gone.

2. Tie a paperclip to the end of a short thread and tie to a pencil or pen to hang in the water with the dissolved solute.  Allow it to sit on a windowsill for several days while the water evaporates. Pull the string out and let the crystals dry overnight.  Record observations of your crystals every day and include the number of crystals, size, shape and other characteristics.

3. Find a good example of each crystal and sketch its shape. Try to find a single crystal without other crystals growing out of it.

Post-Lab Questions:

1. Make a daily log for 5 days of your crystals.  Make a sketch for each(sugar, salt, Epsom salts) one during these 5 days.  Note the number and shape in your drawings. Make it as accurate looking as possible.

2. Which substance grew the largest crystals?

3. How would you describe the shape of each crystal? Describe all three and they will have different shapes!

4. You used three different chemicals to grow these crystals: salt (NaCl), sugar (C₁₂H₂₂O₁₁) and Epsom salts (MgSO₄).  Which of these molecules is the largest (hint: look at their chemical formula)? Did that substance grow the largest crystals? Did the chemical with the smallest molecule grow the smallest crystals? Explain.