Crystals are regular shaped solids particularly with shiny faces. It was first reported by Robert Hooke in 1664 that the appearance is a reflection of a high degree of internal order. Crystals are one of the substances that vary in shape considerably; Steno observed in 1671 that this is not because their internal structure varies but because some faces develop more than others do. You may observe that the angels between different crystals of the same substance are always identical. Each crystal is derived from a basic building block that is continuously repeated in all directions, this is known as the unit cell.
Secondly, growing seed crystals when you are trying to grow a large crystal you must obtain a seed crystal. One of the methods of getting a seed crystal is to pour a small amount of your saturated solution in a plat, let the drop evaporate and scrape the crystals formed on the bottom to use as seed crystals. Another method is to pour saturated solution in a smooth container then dangle a rough object into the solution the same method that you use to make the bigger crystal.
Furthermore, what is Alum?
Alum is a salt that in chemistry is a combination of an alkali metal, such as sodium, potassium, or ammonium and a trivalent metal, such as aluminium, iron or chromium. The potassium based alum has been used to produce crisp cucumber and watermelon-rind pickles as well as maraschino cherries, where the aluminium ions strengthen the fruits’ cell wall.
Finally forming the solution, in order to make a crystal you need to make a solution which can maximize the chances for the solute particles to come together and form a nucleus, which will then grow into crystals. Which means you will need a concentrated solution with as much solute as you can dissolve in it. It is best to start your crystals with a saturated solution. A more dilute solutions the air evaporates some liquids; it will be much quicker if your solution is saturated to begin with. If your solution isn’t saturated well, it will undo your work. Make a saturated solution by adding your crystal solute (e.g. Alum). You should finally stir the mix to help dissolve the solution. Now you are ready to start your experiment.
Aim: The effect of temperature on the growth and size of a crystal, within a short period of time.
Hypothesis: I think if we place one crystal in the freezer and one in normal room temperature, then I believe the one in the freezer will crystals quicker and will slightly be bigger than the one in normal room temperature, because the quicker the temperature cools the more you are rapidly increasing the crystallization rate.
Materials:
- 2 x Beaker
- 2 x Small crystal
- Alum solution (250ml)
- 2 x Pencil
- Scale
- Bunsen burner
- Food colour
- 2 x String (10cm)
- Ruler
- Stop watch
- Alum solution ratio 1:6.9
Crystallization
Method: firstly 250 ml of water is added to 36ml Alum solution (Note: one teaspoon of water = 5 mL; one tablespoon = 15 mL), after have repeated the process two times and placed in separate beakers (or 1/4 cup container such as a small glass or jar), then the mixture has been heated to approximately 60ºC, and left for a few minutes to settle to minimize the chance of your seed crystal on the end of the thread to melt, as well as not applying the crystal to late allowing the crystal to form on the edge of the beaker. After tying a piece of thread to a glass rod, Popsicle stick, pencil or other support object, Have the length of the thread adjusted so that no more than1/2 inch is submerged. Furthermore after applying smear grease (such as Vaseline) or oil (cooking or mineral oil) on the part of the thread above the solution to prevent the solution from creeping up the thread. Once have placed the rod in the beaker and have allowed the solution to form its crystal one in room temperature and the other in the fridge in a safe place. Finally have removed the crystal and observed how it formed on the submerged thread at the bottom of the beaker, and recorded the vital information such as mass, time, temperature, etc.
Results:
Change in mass of two crystals after being placed in an alum solution, each at different temperatures for no more than a period of 24 hours.
As a result you can clearly see the crystal that was placed at cooler temperature happened to crystallize at a much faster rate.
Mass
Temperature:
Discussion and Analysis of results:
-Crystal in room temp:
0.731
--------- X 100 =10.8%
6.73
-Crystal in the fridge:
1.27
-------- X 100 = 14.3%
8.87
The results clearly show that the crystal in the fridge (8*C) had a bigger mass (8.87g) than the crystal in normal room temperature (28*C). When the alum solution was heated to approximately 60*C and left for a couple of minutes to settle, the crystal seed was placed in the solution. It was proven that the quicker the cooling of the solution the quicker the formation of the crystal. However if the crystal doesn’t find a platform to stick to, the crystals will started to crystallize around the base of the beaker, that was also the case in the beaker (room temperature).scientists say larger crystals result in greater time for crystallization to occur, as should be the case if the solution cools slowly. On the other hand, if the solution cools rapidly, less time is available for the ions to organize into large crystals, and the crystals will tend to be smaller. However the experiment proved wrong, it was recorded that the crystal in the fridge had a more rapid growth in the short period of time of 24 hours.
Conclusion: To conclude it was proven that the crystal in the fridge was slightly bigger than the one in room temperature. My hypothesis was very well supported by the results, If we place one crystal in the freezer and one in normal room temperature, then I believe the one in the freezer will crystals quicker and will slightly be bigger than the one in normal room temperature, because the quicker the temperature cools the more you are rapidly increasing the crystallization rate.
Evaluation: There were quiet a number of errors in the experiment some of which are; putting the seed crystal to late, forgetting to cover the beaker with foil and miss reading the temperature. The most impotent thing was the temperature. It has a great affect on the rate of crystallisation, as well as the time that the crystal is left to crystallize. Further experimentation with the Alum, would possibly improve the crystal development and getting more time to work on the experiment (2-3 days). Possibly experiment a little more with the solution or having a group of students that simply grow alum crystals and observe the shape, while other may modify parts of the experiment by placing the beaker in a cooler or warmer condition for further experimentation. Furthermore mixing solutions of salt and alum to see what sorts of crystals are formed and whether the crystals will segregate or grow together, those are all possible ways to discover a lot more about how crystals really form.
