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Activity1Growingcrystals

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ANGELES UNIVERSITY FOUNDATION

Angeles City

INTEGRATED SCHOOL

ACTIVITY 1:

Growing Crystals in the Lab

Year/Section: _____________

Group #: ___ Leader: _________________ _________

Date:____________________

Teacher: _________________

Members: Names

1. _____________________________________

2. ______________________________________

3. ______________________________________

4. ______________________________________

5. ______________________________________

Signature

__________________________

__________________________

__________________________

__________________________

__________________________

Introduction

According to Tarbuck, 2006, “crystal form is the visible expression of a mineral’s internal arrangement of atoms,” As a mineral grows or forms, the atoms that make up that mineral arrange themselves in a certain pattern. If a mineral is given much time and space to form, a crystal with well-identified sides, top, and bottom (called faces) will form. However, most of the time, minerals grow in cramped spaces which result in crystal shapes that are difficult to identify because of their intergrown mass of smaller crystals. You can grow single, large crystals that look like gems by using a seed crystal.

Objectives

To understand on how will crystals formed in the laboratory setup.

To able identify factors needed in growing crystals.

Materials

Lab materials: beaker (100 or 250 mL), graduated cylinder (100 mL), stirring rod, tripod, Bunsen burner, crucible tongs, thermometer.

Reagents or chemical to be used: distilled water, salts, alum (powdered tawas) and other salts (to be identify by the teacher.

Other materials: 6 inch piece of thread, 2 Wide-mouth jar. wood stick, food coloring or dye

Procedure

1. In a 250 mL beaker, heat 100 mL of distilled water to the temperature of 80 o

C.

2. Add the salt (assigned salt) to the water a little at a time stirring the solution constantly. This creates a saturated solution, meaning no more salt can dissolve in the water. (Some undissolved crystals will be at the bottom of the glass.)

3. Add a couple drops of food coloring if you want your crystals to be colored.

4. Filter the solution to remove some impurities. And pour the filtered solution in a wide-mouth jar and label it. Let it stand in a cool dry place.

5. The next day you should see small crystals growing in the bottom of the jar. When they look to be a good size, carefully pour off the solution in a clear wide-mouth jar.

Find a seed crystal with perfect edges (no chips or cracks in the small seed crystal) and tie one end of the thread around the wood stick and the other end around the seed crystal. See Figure 1.1

6. Make sure that the crystal does not touch the bottom of the jar by wrapping excess thread around the wood stick. Wait 7 – 10 days for the crystal to develop.

Figure 1.1 Set-up in growing crystals

7. Make a daily growth record of your crystals. Don’t forget to take pictures for your crystals. This will serve as your documentation during presentation in the class.

NOTE: Cover the jar with a paper towel to keep out the dust and let your crystal grow until you are happy with its size. When you take it out of the solution, set it on some plastic wrap to dry. if you see other crystals growing in the jar, transfer the solution and seed crystal to another clean jar.

Observations (Growth Record of the crystals)

Analysis

1. Describe your crystal—how many sides or faces does it have? What general shape does it resemble?

2. Based in the physical properties of minerals, decide what crystal form (assigned salts and or alum) best resembles. What other minerals have this crystal shape?

3. What is a supersaturated solution? Describe how you made a supersaturated solution.

4. What factors allowed the crystal to form? What factors interfered with the crystal growth?

5. What was the purpose of the seed crystal?

6. Read the major processes by which minerals form. Which of those processes do you think we simulated in the lab? Explain your answer. Think of a situation in the Earth where this might occur.

Summary of Results

Conclusions

References

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