by Louisa Petti
1. What is a crystal?
A crystal is a solid that solid or substance that has a natural occurrence of geometric form with the features of symmetrically arranged plane faces.
2. What substances can be used to make crystals?
There are many substances used to create different types of crystals, and Aluminium Potassium Sulphate, Copper sulphate, Ammonium Chloride, salt and Sodium borate are some examples of chemicals that can grow crystals.
3. What are some examples of crystals in nature? What household items can you also grow crystals from?There are many types of naturally occurring crystals, such as amethyst, quartz, citrine, topaz and agate. Some household items can also produce crystals, such as Sodium (salt), Aluminium potasium sulfate (Alum) and sugar. (for Potash Alum solution)
4. Explain the process of crystal growth.
When a clear solution of chemicals and hot water have been mixed, overnight, small geometric granules form on the bottom of the beaker. These small granules can grow into a large sized crystals and can be connected together or dissolve, but within about a week, the crystal will begin to grow the sizes of 1.5cm to 2cm.
5. Explain how crystals can grow in different shapes and sizes.
Crystals can grow in different shapes and sizes, because of the ranging temperature, pressure and chemical conditions. These variants, especially temperature and pressure and cause a crystal to shrink and even dissolve.
6. What effect do crystals have on light travelling through them? (relate to reflection, refraction, dispersion and diffraction)
Crystals effect light quite differently, compared with other objects, and often have high refraction rates because of how many edges the crystal has. Crystals that have been cut with many edges have higher refraction rates, as well as the diffraction of light, which shows the many reflections of the light on the inside of the crystal. The light dispersion of a crystal is also high, because with the amount of reflected light inside the crystal, it gets very bright and excess light spills out the crystal.
7. What are the optimum conditions for crystal growth?
The optimum conditions of a crystal to grow in, are ones that don't change temperature often and don't have too much sunshine, as you don't want your solution to heat up and dissolve your crystal. Also, keeping a crystal somewhere where there is no movement on the surface, because a crystal needs to be very still to grow. Another way to enhance the way to grow a crystal is to place a nylon thread over the solution.
Put about 25 g of potash alum in a beaker of 250 ml of water and then add approximately 170 ml of hot water. Stir the warm mixture so all the granules have dissolved. The solution may appear to be cloudy.
Then, put the solution through a filter funnel (with filter paper inserted inside) and let it filter into another clean beaker. Cover the new beaker of solution with a watch glass or fresh filter paper and set aside inside a cupboard (somewhere cool) and make sure it goes in there until the next morning. In the next day, a few big crystals should form inside the beaker of solution, and take this crystal out of the beaker and into a new glass jar including the solution, so you can transport it home and grow it up to 10 weeks.
Tuesday – The crystals has grown a lot since last week, the smaller crystals have not grown bigger though. The larger crystal and the smaller crystal have grown to a size about 1-1.5 cm. The solution was 4 cm high. (first pic)
Wednesday – The solution was 3.6 cm high meaning -4 cm less. The crystals stayed the same , it was a bit warm where the crystals were placed and my cat jumped on my shelf and shook up the water a bit loosing more solution. (third pic)
Thursday – The solution did not change at all and the crystals did not grow and the temperature changed and my cat disturbing the solution. (second pic)
-Crystal growth stage & Final Crystal stage-
Solution was about 30 cm high, and the solution evaporated slower and slower during the weeks until the last week (4th). The shape of the first crystal was wide, not really geometric and edgy(like in the 1st pic below). It measured 2.0 cm (length) and 0.9 cm (wide) The crystal's growth seemed to have boomed in the first 2 weeks, but stopped; In the first week the crystal was already quite large measuring at around 0.9 cm length. The second crystal was very geometric and square like with a sharp edge (like in the 2nd pic below). It measured 1.5 cm (length) and 1.1 cm (wide) And shared the same growth rate as its sibling.
The solution first measured out to be 4.3 cm high in the jar in the first day, but a week later, on Tuesday it was about 4 cm high. On the following day it became 3.6 cm because it was warm where the crystals sat and my pet shook the shelf and caused some more of the solution evaporating. In the next week the solution didn't really change until the second last week when it dropped to 3. cm because of the crystals growing a little bit more. When the crystals were removed, the solution finally measured at 2.7 cm, with a 0.3 cm drop. *A table of the results are in another file with activity with caution report :)
I think the way the crystals are photographed show how they are mysteriously different to most objects are because of how they form form a clear solution in a mater of weeks. The contrast of the blue light gives a tense mood of the chemicals used, yet the yellow light with shadows shows how to grow a crystal in a constant envionment.