Year 9 Task, By Remi Oswald
What is a crystal?
A crystal is a solid substance that has been formed by a regular and repeated pattern of molecules that have connected together. In some soilds, the arrangement of the particles can often be in a random arrangement, in crystals the atoms are repeated in exactly the same arrangement over and over again throughout the entire material.
What substances can be used to make crystals?
- Aluminium potassium sulphate dodecahydrate
- Ammonium Chloride
- Calcium Chloride
- Sodium Nitrate
- Cupric (Copper) Sulphate
What are some examples of crystals in nature?
- Table Salt
.25 grams of potash alum
.2x 250 ml beaker
.170 ml of hot water
.watch glass/more filter paper
1. Place approximately 25 g of potash alum in a 250ml beaker
2. Add 170ml of hot water
3. Stir the mixture until the crystals have dissolved, the solution may be slightly cloudy which is perfectly fine.
4. Filter the warm solution through a filter funnel (with the filter paper inserted) into the second clean beaker.
5. 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.
6. The first beaker and funnel can be cleaned and dried and the waste and filter paper can be thrown out.
· 2x 250ml beaker
· stirring rod
· plastic spoon
· (left over potash alum)
· smart phone/camera
· log book/diary
· loose fitting paper hat
1. Observe the beaker containing the solution. The bottom should be covered with a small layer of crystal because the solution is cold.
2. Gently decant (pour off) the clear liquid above the crystals into the clean beaker and set aside. Make sure the crystals are left in the other beaker. If no crystals have formed overnight, you can seed the solution. Do this by adding crystals from the original alum and let it sit overnight again. You may also need to stir the solution with your stirring rod.
· 2x 250ml beakers
· smart phone
· log book
1. Choose one good symmetrical crystal or group of crystals to act as the ‘seed’ for your large crystal. Using your plastic spoon, tweezers, tongs or spatula transfer the chosen crystal into the middle of the beaker with decanted solution. NOTE: If you want the crystal to grow rapidly suspend the crystal with a nylon thread tied to a pencil resting on the rim of the beaker.
2. Take a picture of the crystal in line with the ruler so you measure its size and mark the level of liquid in the beaker.
3. Record this in your logbook.
4. Cover the solution with a loose fitting paper hat that allows water to slowly evaporate and keep out foreign particles. Keep it somewhere where the temperature will stay constant.
Over The Holidays
1. Once a week record the level of liquid in the beaker and without moving the crystal take a photograph of it next to the ruler.
2. Estimate and record how much the crystal has grown. NOTE: Try to avoid disturbing the crystal as much as possible. Don’t touch the crystal with your fingers!
3. If any isolated crystals appear you can remove them gently with tweezers. If small crystals begin to form on your main crystal dry and remove them with a tissue.
4. If the crystal isn’t growing anymore you can create a new solution using the pervious steps and gently transfer the crystal once the solution is room temperature. The solution may need to be left overnight to cool before the crystal is added.
5. Once the experiment is over, remove the crystal extremely carefully from the beaker, dry it with a tissue and measure its length, width and height with a ruler. Compare the measurement to the original size of the crystal in your logbook.
- Table Salt
Explain the process of crystal growth?
Sodium and Chlorine atoms make up an ionic bond (both share a pair of electrons). While in solution, the Sodium and Chlorine are separated by water molecules. As the water evaporates from the solution, the Sodium and Chlorine atoms begin to bond together, first as single molecules and then the molecules bond together, forming crystals. Every molecule will form the same shape crystal each time it forms. The crystal shape for salt is a cube like a six-sided die.
Explain how crystals can grow in different shapes and sizes?
Crystals can come in many shapes and sizes. For example, you can see triangle shapes in crystals like rubies and amethysts. The unit cells always stack together in a regular pattern to make a crystal. Perfect crystals have only straight edges, but most of the crystals we see in nature aren't perfect. They often grow in small compact spaces in the ground and don't have the room to grow into even directions/creases. So they may have some straight edges, but look rounded or jagged in other places.
Outline a few types of Crystals:
Rubies, Diamons, Emeralds and Sapphires have been a popular types of crystals for heaps and heaps of years. They are highly valued due to their beauty and popularity rate. There also opals which is an Australian crystal, not so rare in the outback. Plenty are gathered each week. Salt is used in day to day cooking and cleaning. Sugar is used in cooking alswell; as you can gather, salt and sugar are both common crystals.
What effects do crystals have on light travelling through them?
Light acts differently depending on where the direction of light is reflecting towards the crystal. The index of refraction depends on both the composition and crystal structure within it. When light hits the crystal at a certaint point there will be reflection. In some cases the light can be blinding (which is a distinctive value that makes some crystals so special) but it does depend on the crystal.
What are the optimum conditions for crystal growth?
Warmth is the key to forming crystals. The surrounding of the jar should be warm for the best outcome on your crystal growth. Warm air temperature helps water evaporation, causing the crystals to grow more rapidly. Crystals will still grow in colder temperatures, but it will take much longer for the water to evaporate. Crystal growth also requires light. Again, the crystals will eventually grow in the dark, but it will take a very long time. Light evaporates water as heat does.
What are some examples of crystals in household items?
- Today our group completed the practical componment of the task; we put all the ingredients together, followed the method and put on the window ceil to rest.
- We are hoping will find crystals tomorrow in class.
- Today when we went to see our crystals we found that numerous amount of small crystals rocks had been formed.
- We are very happy with the outcome so far!
Holiday Observations- Week 1:
My crystals haven't changed since my last observation, but i'm hoping they will soon they will grow!
Holiday Observations- Week 2:
My crystals have grown more!
The solution inside my jar has completely dissolved and i'm happy with my final product!