Growing Crystals

Elsa McConville

Questions:

1. What is a crystal?

A crystal is a translucent, hard object with many faces. A crystal is formed when molecules form together in a precise regular repeating pattern. Different bonds of molecules are in different crystals.

2. What substances can be used to make crystals?

Potassium Alum, Ammonium Chloride, Sodium Borate, Calcium Cholride, Sodium Nitrate, Cupric Acetate and many, many more. Each substance can grow different types of crystals with colour, size and shape varying.


3. What are some examples of crystals in nature? What household items can you grow crystals from?

Crystals can be formed in many different ways. Some crystals such as rubies or tapaz, are formed in the holes of volcanic rock these are called magmatic crystals. Others are formed when they are in water and then the water evapourates leaving them behind. Crystals like this include salt crystals in salt water.

4.  What is the process of crystal growth?

Most of the time, crystals are formed by gradually cooling molten rock. This can happen during a volcano. Jewels like diamonds and rubies are formed this way. You can get salt crystals when water evaporates.

5. Explain how crystals can grow in different shapes and sizes:
Crystals grow in different shapes and sizes when they grow from different substances and the bonds of molecules differ in each crystal.

6. What are some Different types of crystals?

Rocks, snow flakes, salt and sugar crystals, etc.

7. What effects to crystals have on light?

Crystals refract light when it moves through the crystal. Because all crystals are more dense than air, they refract light towards the normal the the light enters them. Diamonds are cut a special way so that when light enters them, it does total internal reflection, and this is why diamonds sparkle so much.

8. What conditions are optimum for growing crystals?

Warmth is best when growing crystals, and keeping the beaker away from light. You must cover the beaker as well. Vibrations stop/slow down the crystal growing process.

Plan

Day 1:

Place approximately 25 g of potash alum in a beaker (250 ml or bigger) and add approximately 170 ml of hot water. Stir the mixture until all the crystals have dissolved. The solution may have a slightly cloudy or milky appearance due to impurities in the technical grade of alum used.

(NOTE: don’t use all the alum you have been given – keep a few crystals back in reserve in case you need to "seed" the solution later.)

Filter the warm solution through a filter funnel (in which filter paper has been inserted) into another clean beaker. Cover the beaker of solution with the watch glass or fresh filter paper and set aside in a cool sheltered place and allow it to stand undisturbed overnight. take photo

Day 2:

The bottom should have become covered with a layer of smallish crystals which formed spontaneously as the solution cooled. Carefully decant (pour off) the clear solution above the crystals into a clean beaker and set it aside for later, leaving the crystals behind in the other beaker. If for any reason, no crystals have formed after leaving the solution to stand overnight, the solution can be "seeded" by adding a crystal from the original alum. Let it stand overnight again and observe the formation of crystals. Alternatively, if nothing has happened, crystal growth may also be induced by scratching the bottom of the glass beaker with a glass stirring rod.

From the bed of crystals, one good symmetrical crystal or group of crystals needs to be selected to act as "seed" for your big crystal. Using a plastic spoon, spatula, tongs or tweezers, transfer the selected crystal to the beaker containing the decanted solution, trying to place it centrally in the beaker.

Take a picture (if possible) of the crystal, preferably close to a ruler so that you can measure its size, and mark the level of the liquid in the beaker. Record the date in your diary.

Cover the solution with a loose-fitting paper hat that permits water to evaporate slowly whilst keeping out dust. Allow the solution to stand in a draft free location, not in direct sunlight or near a heater. The aim is to keep the temperature as constant as possible.

Day 3:

Take a photo of crystal/crystals, continue observations at home.

Observations

Day 1: Took Crystals home today. I placed the jar in a cool dry area away from the sun.

Day 3: Moved crystals outside under veranda roof. Crystals have grown quite a bit and the largest one's tip is now poking out of the liquid.

Day 7: Came back form holiday and crystals had grown a lot. New crystals had formed at the bottom and had sort of clumped together. There are now two large ones and both of them are taller than the the liquid now.

Day 10: Have not grown that much, but the changes are still noticeable. More have formed along the bottom but the largest crystals haven't grown much.

Day 13: Got home from holidays and was unable to find my crystals. No evidence of broken glass or jar where I left it. :(

How To Grow Crystals Crossword

ACROSS

2: What you put on top of your beaker to stop dust getting in, and so that the substance can evaporate.

5: A breach in safety that could pose as a potential risk.

7: Clear, sparkly and famous crystal.


DOWN

1: What happens when light travels through crystals?

3: What chemical substance is used in step 1?

4: Famous transparent red crystal formed in volcanic rock.

6: A small crystal that is placed in a fresh beaker to grow a bigger one in step 2.

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