Lab Report

Constructing a Solubility Curve

Dr. Forman

Julia, Clemmy, Koroush

Purpose: To collect experimental data in order to construct a solubility curve for succinic acid.

Background/Significance: After being taught the rules of solubility, we were able to comprehend and test the solubility for succinic acid. By doing so, our understanding of solubility expanded and we were able to create a graph, which showed various amounts of solute at different temperatures.

Abstract: The intention of this lab was to recognize the solubility curve and to examine the solubility in each substance. Clemmy, Koroush and I took in many vital educational skills from the “Constructing a Solubility Curve” Lab. By testing the solubility of succinic acid and collecting the data from all the three different temperatures we were able to confirm the given presumption that solubility increases when the temperature increases. Not only were we all working together to get these conclusions, but we stayed organized the entire time leading us to positive results. 

Procedure:

1.   Prepare a warm water bath on a hot plate with about 300 mL of water and heat it to 45 degrees C

2.   Fill a test tube with 4-5g of succinic acid and add 20 mL of distilled water

3.   Place the test tube in the warm water bath and stir the succinic acid solution with a glass stirring rod every 30 seconds:

4.   Decant the clear liquid into a separate test tube

5.   Carefully pour the hot water from the beaker into the sink

6.   Place the new, separate test tube in an ice bath for 2 minutes, stirring occasionally

7.   Tap the side of the test tube and swirl the liquid once or twice so that the crystals settle evenly at the bottom

8.   Measure the height of the crystals in millimeters

Results:

Our group was able to record excellent results and at the same time observe that as the temperature increased so did the solubility. With our first and lowest temperature, 45 degrees C, the solute partially dissolved in the warm water bath. After removing the test tube from the ice bath, our group noticed that there were many small white particles floating throughout the mixture and there were also tiny white solute crystals that sunk to bottom of the test tube. With our medium temperature, 55 degrees C, the majority of the solute dissolved in the warm water bath. After we removed test tube from the ice bath, we found that most of the test tube was filled up with crystals. Finally, with our last and warmest temperature, 65 degrees C, the solute was dissolved 100% in the warm water bath. Following with the ice bath, we were able to see that the test tube was completely filled with crystals. After recording all of this data, we finally came to the conclusion that as the temperature increased the solubility of succinc acid increased as well. 

  

Data analysis:

1. The mean crystal height for the data obtained by the entire class was 14.1mm for 45'C, 101.3mm for 55'C, and 102.8mm for 65'C.

2. The mean crystal height in mm verses water temperature in the Celsius graph -

Lab group results:

Class results:

Questions: 

1. It could be useful to do more than one trial at a particular temperature because the results could be different since there are sometimes small changes in temperature, the time mixing the solution, and the amount of time that the solution is left to sit in the hot water, the ice water, and in room temperature. 

2. Succinic acid is a solid solute and not a gas. This is how we know that when the temperature of the water would rise so would the solubility of the succinic acid.

3. Yes, all the succinic acid that originally dissolved in the water crystallized out of the solution. When cooling the clear solution in an ice bath after separating it from its original test tube we allowed it to sit in room temperature for five minutes, re-crystallizing all of the succinic acid that was originally dissolved in the heated water. 

4. Yes, we did have enough data points to make a reliable solubility curve for succinic acid because every group recorded all of their data. However, the curve was not precise enough to make useful predictions about succinic acid solubility at temperatures that we have not yet investigated. This is because we only experimented with three different temperatures; however, if we had experimented with more temperatures, our graph would have helped us make more useful predictions. 

5. The difficult factor of this experiment was the many factors could change each individual group's results.  Wrong measurements of temperatures, too much or too little succinic acid, dirty tools, and too much or too little time being heated and cooled are all possible factors that could have lead to errors and inaccurate data.

6. A different procedure for gathering data in order to construct a solubility curve would have been to take a substance and fill it with water at a certain temperature. Then, wait for the water to become a saturated solution and change the temperatures in order to obtain different results.