Growing Crystals (Page 2 of 3) in pdf

Growing Crystals Page 2

Student Lab Day 2

1. Carefully remove one of the largest crystals with tweezers. Tie a piece of string around it and wrap

the string around the middle of a pencil. Use tape to secure the pencil and string if necessary.

2. Send a student from your group up to the front of the

Chemical Colorings

room to pour 5-6 mL of dissolved Alum your teacher set-

The colors of gems often come from

up into your beaker. Choose a gem color if you desire,

chemical impurities, just as your

red to make a Ruby, or green to make an emerald. Use

home-grown crystals are colored by

approximately 1 drop. Then place the pencil on top and

additives. Rubies and sapphires are both varieties of

hang down the string with the crystal being suspended in

the mineral corundum, which is colorless when pure.

the solution.

Rubies get their red from chromium, while sapphires

are colored various colors by iron and titanium.

3. The crystal will grow slowly. Record observations

below.

Day 1

Day 2

Day 3

Observations/

Sketches

Day 3

1. Today you will mass your final crystal to compete with your classmates! Who grew the largest crystal?

Mass of final alum crystal _____________g

Rock Matching

1. Igneous __________

A. degree of crystallization depends on the conditions in which they

solidified (cooled slowly or rapidly)

2. Metamorphic ___________

B. re-crystallized with high temperature and pressure

3. Sedimentary ___________

C. deposited from aqueous solution

Conclusion Questions

1. On a scale of 1-10, with 10 being the best rate your crystal in terms of a. shape ___ b. clarity ___c. size ___

2. What measures could you have taken to improve the shape?

3. What measures could you have taken to improve the clarity?

4. What measures could you have taken to improve the size of the crystal?

Growing Crystals Page 2