solubility curve lab

Livia 

Stephanie 

Lex 

Abstract

The purpose of this lab was to construct a solubility curve for succinic acid, which is a molecular compound. During this procedure, we tested the solubility of the acid at three different temperatures, 45 degrees C, 55 degrees C, and 65 degrees C. In doing so, we used several different lab tools and methods, like heating beakers, decanting liquids, and measuring crystals. At times, this lab was difficult due to the multiple steps and repetition of those steps. But eventually, these steps became routine and we were able to complete the lab successfully. Safety was also a main concern during this procedure, because of the toxicity of the acid. In order to prevent an accident from occurring, communication was necessary amongst our lab group. We made sure we were done using every liquid before discarding it, and were careful when removing the beaker from the hot plate.

          

Procedure

First, we added about 300 mL of water to a 400 mL beaker. Then we heated the beaker using the hot plate to 45 degrees C. After that, we placed 4.5 g of succinic acid in two test tubes.

 Next, we added 15 mL of distilled water to each test tube. 

Then we placed each test tube in the warm water bath and stirred the succinic acid solution every 30 seconds for 7 minutes. After the 7 minutes ended, we decanted the clear liquid from each test tube into an empty test tube. 

We then prepared an ice bath in another 400 mL beaker and put the two test tubes with the clear liquid in the ice bath for two minutes. Then we stirred the liquid, removed the test tubes from the ice water, and let the tubes sit at room temperature for 5 minutes. 

After swirling the liquid, causing the crystals to settle evenly on the bottom, we measured the height of the crystals collected in millimeters, which came out to be 5 mL in one tube and 19 mL in the other.

We repeated these steps twice, but instead heated the beaker to 55 degrees C, with the result of 5 mL and 18 mL of crystal, and 65 degrees C, with the result of 4 mL and 2 mL crystal.
We noticed that after soaking our tubes in the ice water, it took quite awhile for them to cool down and for the remaining crystal to form. Because of this, it took us longer than expected to complete the lab, but eventually we finished.
After comparing our results with the rest of the class, we found that we had far less crystal content in our tubes, and the amount of crystals we measured in each tube were completely unalike, for example 5 mL and 18 mL.
 This could have been due to the fact that two different students decanted the liquid in the test tubes and could have distinctive methods, or maybe one was more conscientious when removing the liquid than the other.

Trial	Crystal Height
1 (45 degrees C)	5 mL, 19 mL
2 (55 degrees C)	5 mL, 18 mL
3 (65 degrees C)	4 mL     2 mL
Average	9 mL

Aggregated Class Data

	Atoms	Ions	Molecules	Average
45 degrees	13 mL, 11 mL	5 mL, 19 mL	10 mL	11.6 mL
55 degrees	13 mL, 14 mL	5 mL, 18 mL	14 mL	12.8 mL
65 degrees	16 mL, 6 mL	4 mL, 2 mL	18 mL	9.2 mL

1. It is useful to collect data from more than one trial at a particular temperature because you're given the opportunity to find the average out of all the data, to make up for any small errors made within each procedure.

2. We knew that when the temperature of the water was increased, the solubility of the saturated solution should have also increased. 

3. In our procedures, most of the succinic acid crystallized out of the solution. In certain test tubes, however, much of the acid was already dissolved which made it difficult to measure  the crystallization.

4. The data collected amongst the class wasn't very sufficient because out of the three groups, our group's data became the outlier. Then, there were only two groups left and it is very difficult to construct a proper solubility curve for only two groups. 

5. The decanting of the liquid could easily lead to errors, because of how easy it is to add the succunic acid precipitate into the rest of the liquid. Other errors like false measurements could also lead to errors.

6. A different procedure to test the solubility of a liquid could be to keep the liquid at the same temperature for every test, but to change the actual amount of the liquid. So in one test you could start with 400 mL. then 300 mL, then 200 mL and see how much the solubility changes.