Crystallization

Lab # 4
Crystallization

Jonathan Odell
Partners: Allyson Chiu
Michelle Jung
Regine Ong
Day 1 Period 3
Experiment conducted: November 15, 2012
Submitted date: November 21, 2012

Introduction:
In this lab, the students were separated into groups of four in which were given a test tube that was half full of hydrate sodium thiosulfate. The experiment’s purpose was to observe the reaction of the hydrate sodium thiosulfate in different situations, such as being shook over a period of time, or place another hydrate sodium thiosulfate pellet in its liquid form. This allows the students to observe the process of crystallization. Throughout the experiment, the students are asked to melt the hydrate sodium thiosulfate into liquid form, having no definite shape but a definite volume. Hydrate sodium thiosulfate melting point is 48.3 oC.
Crystallization is a liquid and solid chemical separation that takes place due to mass transfer of a solute from the liquid solution to a pure solid crystalline, a phase that occurs after the reaction occurs. The hypothesis is that the hydrate sodium thiosulfate will crystallize after being shaken in a fast, repetitive motion. This will be because of the kinetic energy that will be present when the liquid is being shaken around. Kinetic energy, being constant energy used at work which would be the kinetic state, is one of the two types of energy that can be in one or two states. The other is potential energy which is stored energy.
The independent variable was the amount of hydrate sodium thiosulfate put into the test tubes. The dependent variables were the time it took for the hydrate sodium thiosulfate to melt and the process in which the test tube took to crystallize. The constant variable was the hydrate sodium thiosulfate.

Materials: 1) Test tube 2) Hydrate sodium thiosulfate (half test tube worth) 3) Hot plate 4) Beaker 5) Stoppers (test tube) 6) Safety goggles 7) Distilled water 8) Clear dish
Procedures:
1) Got into a group of four and then split into two groups of twos. One group will have test tube A and the other group had test tube B. 2) Filled both of the test tubes half full with hydrate sodium thiosulfate. 3) Added four droplets of distilled water in each tube. 4) Got a beaker and filled it with water, then placed it on a hot plate, waiting for it to heat up. 5) Both the test tubes were placed into the water and waited till the hydrate sodium thiosulfate had melted. 6) After both melted, the tubes were taken out of a beaker and placed under running cold water, which was to cool it down. 7) After cooled, the test tube A group applied a test tube stopper to the test tube and shook rapidly until crystallization took place. Test tube B group poured the liquidized hydrate sodium thiosulfate onto a clear dish and added a pellet of solid hydrate sodium thiosulfate. 8) After the groups observed the process, the lab area was clean and everything was nicely put away.

Data:
Test tube A The test tube was crystallized, as shown above, after shaking it rapidly and repetitively for awhile. The change in temperature was quick and very noticeable, rising at a fast speed.

Test tube B After placing the pellet of hydrate sodium thiosulfate in the liquidized hydrate sodium thiosulfate, the crystallization began, also having a change in temperature.

Discussion:
The purpose was achieved. Crystallization did happen, allowed the students to observe the process. The hydrate sodium thiosulfate did not freeze because of the potential energy being held inside which did not allow heat to be given off. In the process of shaking the test tube, this allowed the hydrate sodium thiosulfate to have kinetic energy and gave off heat, which then led to it freezing. The second test tube was quite different. A small pellet of hydrate sodium thiosulfate was placed in the liquidized form of hydrate sodium thiosulfate and then became the same temperature as the solid form, which transferred heat between the liquid and the solid, leading to crystallization.
No errors were found in the process, which allowed the lab to be a 100 percent accurate, being able to see a thorough crystallization process.

1) Potential Energy
2) Activation energy
3) Kinetic Energy - Crystallization
Conclusion:
The hypothesis was correct and the lab was successful. This lab showed the students the process of crystallization also how kinetic and potential energy work.