Lab 30: Factors Affecting Solution Formation

April. 22rd

               Lab 30: Factors affecting solution formation

    In this experiment, we tried to investigate the factor that affect the rate of solution formation. A solution consists of two parts: solute, the material that is dissolved; solvent is the material that the solute dissolved in. Stirring (agitation), temperature and the surface area of the dissolving particles determine how fast the substance will dissolve.

    Then, talking about the experiment. After putting the googles on, I labeled four large test tubes and used a marker wrote 1-4 on them. Then, by using a spatula, put four pea-sized crystals of copper(II) sulfate pentahydrate (CuSO4·5H2O) on a piece of weighing paper. Then, put one crystal into tube1 and another into tube 3. Crush the rest of 2 crystals with mortar and pestle and pour the powder into the tube 4, copper(II) sulfate pentahydrate is toxic and irritating, avoid contact with this material . After that, fill all four test tube about one-third of water. And place number 1 and number 3 test tubes on the test tube rack, and flick test tube the second and forth ones. And write down how long does each one of them take to dissolve on the data table. While leaving the first and the third test tubes on the test tube rack, we can start the second part of the experiment. Add 50 ml of distilled water to a 100ml beaker, and put it on a heater, and start heating it. While it is heating, half-filled a 100 ml beaker with crushed ice and then added approximately 30 ml of distilled water into the beaker. While the water is chilling, I took 3 large test tubes and wrote 1~3 on it with markers. After that pour the sodium chloride in each test tube averagely, and put them in the test tube rack. After a while, when the ice water had chilled for some time, fill one-third of the first test tube with it; fill one-third of the second one with distilled water at room temperature; and filled one-third of the third one with hot water that almost boil, while pouring the hot water from the beaker, use some towels to cover the beaker to prevent get burned by the heat. And gently flick these test tubes and record how long does it take to dissolve on data table 2.

    In the first part of the experiment which involved copper(II) sulfate pentahydrate, the forth test tube dissolve the fastest, 4.32 min, it was flicked and the solid was in powder form, the solution was a very uniform transparent blue solution. The second fastest one is the second test tube, 11.43 min, it was flicked and the solid was in pea-sized crystal form. it looked exactly the same as the forth test tube. The next one, is test tube number 3, although I did not had the chance to see it fully dissolved, but I still I can determine the dissolving speed is much faster than the first test tube, it was not flicked but the solid is in powder form, the solution was blue and transparent, but it was lighter than the second and the forth test tube, and there was some solid particles at the bottom. The slowest one is the first test tube, it was not flicked and the solid was in pea-sized. The solution was not uniform, there was some blue at the top and bottom, but in the between, there was no color and there are some solid at the bottom. So the speed of dissolving for this experiment is( from fastest to slowest)  test tube No.4 >No.2 >No.3 >No.1. For the second part of the experiment, in the first test tube, it took the sodium chloride 12.34min to dissolve in 4°C, and it formed an uniform transparent non-color solution. For the second test tube, the sodium chloride dissolve in 7.30min when the water temperature is 26°C and formed the same exact solution as the first test tube. And in test tube 3, it took 6.26 min of sodium chloride to dissolve in 90°C water, and formed the same solution as the first test tube.

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