The purpose of the foul water lab experiment is to clean up a sample of foul water and hopefully purify it enough to be suitable for hand-washing. The procedure of cleaning the water includes three parts; first, oil-water separation. Oil-water separation is the process of using a Beral pipet to remove the top layer of the foul water sample; the thick layer of oil. By the end of this process, my group, Team Metal, had removed almost all oil. The second part of the process is Sand Filtration. Sand filtration is executed by poking small holes into the bottom of a (styrofoam) cup. Then, one must fill the cup with sand and gravel and pour the oil-free soiled water sample into the cup, allowing it to pass through the sand and gravel filter. The filtrate is released from the small holes into a beaker. After this step, my group's filtrate was very dark yellow in color, and did not have enough sand particles to make re-filtering necessary. The third part of the process is charcoal adsorption and filtration. In this step, one must place folded filter paper into a funnel with a beaker underneath. A clay triangle and a ring stand holds these materials in place. After mixing the filtrate with a semi-fine and then ultra-fine charcoal, it is poured into the funnel, and gradually drips filtrate into the beaker. This was the last step, and by the end of this step, our filtrate was completely clear and free from all visible matter such as sand and oil.
First, we were given 100mL of foul water, that stunk of garbage, waste, and coffee, from Dr. Forman. After the sample sat in the graduated cylinder for about a minute, we noticed that the a thick layer of what looked like oil had settled atop the very murky water. By this time, we were able to begin the oil-water separation. We used a Beral pipet to remove as much of the top layer as possible, and placed it into a dry test tube.
My lab group recovered 69% of our original foul water sample as purified water; this was our percent recovery. We lost 31mL of liquid, or 31% of our original foul-water sample.
Histogram: This shows the percent recovery obtained by all the laboratory groups in the class.
The average percent recovery for my class is 64.5%
The median value of the percent recovery data is 65.5%
Electrical conductivity is the way to test whether or not water contains salt. Since salt is a conductor, if an electrical current is present when the water is placed under a light bulb, it will light up. If this occurs, in order to purify the water to make it suitable for hand washing, it is necessary to distill the water.
Distillation was our final step in purifying water in order to make it clean enough for hand-washing. Distillation is the process of separating salt from water. Dr. Forman demonstrated the process of distillation for the class. First, he placed water into the larger round flask of the distillation train. Then, he heated water at 99.1°. Because water has a lower boiling point than salt, the water evaporated into the upper tube of the train. It then condensed in the upper, bar-like compartment and fell into the smaller round flask on the other side. Since the salt did not evaporate due to the insufficient measurement of heat it needed to boil, the salt remained in the larger round flask, separated from the newly distilled water in the smaller round flask.
The presence or absence of the Tyndall Effect: In order to test if there were particles inside water, Dr. Forman shone a light (lazer pointer) horizontally, through both murky, and distilled water. Since the beam of light shone all the way through the murky water, we could confirm that the water was not totally pure and needed to be distilled. On the other hand, when the lazer pointer was shone horizontally through distilled water, light was only visible at the edges of the glass beaker. From this, we could confirm that the water lacked salt and dirt particles and was completely pure.