Solubility Lab Report: The Metals

ABSTRACT:

The objective of the solubility lab was to test the solubility of succinic acid (C4H604) at three different temperatures. Our main concern at the beginning of the lab was working with this slightly toxic acid. This placed much importance on being very careful and listening to and following instructions thoroughly. Although this lab may seem simple, one mistake may easily falsely change the results. In order to be safe, we wore latex gloves at all times and only handled the test tubes with tongs to protect us from the heat. Going into this experiment, we knew that the solubility of succinic acid would rise with temperature because succinic acid is a solid at room temperature; therefore, we knew if our results showed the solubility going down, that a mistake must have been made. In this experiment, we used a lot of laboratory equipment: a plastic weighing boat, a 400 mL beaker to heat the water, six test tubes, a stirring rod, a thermometer, a graduated cylinder (for measuring degrees in celsius), a scale, a beaker tong, a scale, a large beaker to cool the water in an ice bath, and a heater. First, we added 300 mL of water to our beaker, heated it to 45°C on the heater, added 4 grams of succinic acid and 15 mL of water to a test tube, and placed it in the heated water bath of the beaker. After the solution had been stirred for seven minutes in 30 second intervals, we put the test tube in a cold iced water bath for two minutes and then let it sit in room temperature in the beaker stand for five more minutes as the solute settled to the bottom of the test tube. We measured the solute after five minutes and repeated this process with 55°C and 65°C. At the end of the whole procedure, we recorded our data and found our average solute measurement (11.66 mm of succinic acid).

PROCEDURE:

Our first step to begin the process was to organize all of our laboratory equipment carefully; any mistakes to the seemingly simple process could lead to inaccurate data and disorganization. At first, our group, The Metals, had trouble with our heater and soon found it was broken. We began the lab experiment with what felt like chaos, but once we had a working heater and all of our equipment laid out in front of us, the procedure went smoothly! To begin the actual procedure, we filled our 400mL beaker with 300mL of tap water. We then placed it on the water heater that, and turned it on to its highest setting, 6. The reason why we set it to its highest setting was to get the water heated as quickly as possible, for due to our earlier mishap with the broken heater, we really needed to regain momentum. We placed our thermometer into the beaker, and once it reached our first temperature, 45°C, we lowered the setting on the heater, in order to maintain the heat of the water. We used the weighing boat and a very sensitive scale to carefully measure out 4 grams of succinic acid (C4H6O4) three times. We placed each 4 gram measurement of the succinic acid into 3 different test tubes and added 15 (not 20 due to the small test tubes) mL of water to each tube; by doing this, we would be prepared for each step of the process on time. Due to some confusion, we placed two tubes into the heated beaker, and although using the thermometer we were able to measure the heat of the tap water in the beaker to 45°C, the solution within the test tubes remained at 43°C; this was okay, however, because as long as the temperature of the succinic acid solution was within 2°C of the target temperature, it was acceptable. For 7 minutes, every 30 seconds we would use a stirring rod to mix the succinic acid solutions in hopes of increasing the solubility. After seven minutes had passed, we used the beaker tongs to remove the test tube from the water. We then extracted the liquid from the tube with a beral pipet and put it in a new, clean test tube (leaving the un-disolved solute in the original test tube). Then, we placed the new test tube into an iced water bath. Our test tube sat in the water bath for two minutes, and after two minutes, we took it out of the cold water and put it into a test tube rack to sit in room temperature for five minutes. At this time, our solution appeared to be clear. After waiting five minutes, the solution was still clear; therefore, due to our lack of solute, 0 mm, our group was able to conclude that succinic acid was practically insoluble at 45°C. Next, we increased the heat of the heater in order to raise the temperature of both the tap water within the beaker and the solution within the test tube to 55°C. Using the thermometer, we found that we were able to obtain a 55°C temperature in the water in the beaker, and a 54°C temperature in the succinic acid solution. Again, we used a stirring rod to mix the solution for for 7 minutes in thirty second intervals, in order to mix the solute into our distilled water solvent. After seven minutes had passed, we used our beaker tongs to remove the test tube from the heated water. We extracted the liquid from the tube with a beral pipet and put it in a new, clean test tube (leaving the un-disolved solute in the original test tube). Then, we placed the new test tube into our iced water bath for two minutes. This time, however, when we took the test tube out of the water bath, we noticed significant amounts of solute settling to the bottom of the tube. After five minutes of sitting in the test tube holder at room temperature, there was 15 mm of solute at the bottom of the tube. Finally, we were ready for our last portion of the procedure, finding the solubility of succinic acid in 15 mL water at 65°C. Since we had not placed our prepared test tube of distilled water and four grams of succinic acid in the beaker atop the heater in the beginning, we had to spend a bit more time heating our test tube. Once we brought the heat of both the water in the beaker and the water within the test tube to 65°C, (and repeatedly used the thermometer to check the temperatures of the water in the beaker and the succinic acid solution), we lowered the setting on the heater from 6 to about 1. We were then ready to begin the process. We repeated the process of using a stirring rod to mix the succinic acid solution for 7 minutes in thirty second intervals. After seven minutes had passed and the distilled water solvent was as mixed with succinic acid as it could be, we used our beaker tongs to remove the test tube from the heated water. We extracted the liquid from the tube with a beral pipet and put it in a new, clean test tube (leaving the un-dissolved solute in the original test tube). Then, we placed the new test tube into our iced water bath for two minutes. By the end of the two minutes, we noticed a more solute settling to the bottom of our test tube than the amount that settled in the solution created at 55°C. With this observation, we knew we were getting (semi) accurate data. After five minutes of sitting in the test tube rack, we measured 20 mm of succinic acid settled to the bottom of the tube. After carefully recording all of our data and observations, we were ready to clean up all of the equipment and our area, and prepare to find our average, and the class average of crystal height obtained at each temperature.

Water temperature being measured:

Solubility of succinic acid: From left: 45°C, 55°C, 65°C:

OVERVIEW OF RESULTS:

Us, The Metals:
-Solubility of succinic acid at 45°C: 0mm of settled succinic acid at the bottom of the test tube; 0mm solubility.
-Solubility of succinic acid at 55°C: 15mm of settled succinic acid at the bottom of the test tube; 15mm solubility.
-Solubility of succinic acid at 65°C: 20mm of settled succinic acid at the bottom of the test tube; 20mm solubility.
Our Average (of all three temperatures): 11.66mm solubility

Class Average: Since only two of the groups successfully obtained three sets of data for each temperature, 45°C, 55°C, and 65°C, we only included two groups, The Acids and The Metals, in our calculations for the class average.
-Solubility of succinic acid at 45°C: 1.5mm of settled succinic acid at the bottom of the test tube; 1.5mm solubility.
-Solubility of succinic acid at 55°C: 25mm of settled succinic acid at the bottom of the test tube; 25mm solubility.
-Solubility of succinic acid at 65°C: 28mm of settled succinic acid at the bottom of the test tube; 28mm solubility.

Class Data:

Class Average:

DATA ANALYSIS:

1. Find the mean crystal height obtained by your entire class for each temperature reported.

Because only two of the groups successfully obtained three sets of data for each temperature, 45°C, 55°C, and 65°C, we only included two groups, The Acids and The Metals, in our calculations for the class average. For the procedure executed to find solubility of succinic acid at 45°C, our group, The Metals, measured 0 mm of settled succinic acid at the bottom of the test tube; 0 mm solubility. The Acids measured 3 mm settled succinic acid at the bottom of the test tube; 3 mm solubility. The average of the two groups at 45°C was 1.5 mm settled succinic acid at the bottom of the test tube; 1.5 mm solubility. For the procedure executed to find solubility of succinic acid at 55°C, The Metals measured 15 mm of settled succinic acid at the bottom of the test tube, or 15 mm solubility, and The Acids measured 35 mm settled succinic acid at the bottom of the test tube, or 35 mm solubility. The average of the two groups at 55°C was 25 mm settled succinic acid at the bottom of the test tube; 25 mm solubility. The last test we conducted was to find solubility of succinic acid at 65°C. Once again, The Metals measured less than The Acids, measuring 20 mm of settled succinic acid at the bottom of the test tube, or 20 mm solubility, while the Acids measured 36 mm of settled succinic acid at the bottom of the test tube, or 36 mm solubility. The average of 65°C was 28 mm of settled succinic acid at the bottom of the test tube; 28 mm solubility.

2. Plot the mean crystal height in millimeters (y-axis) versus the water temperature in degrees Celsius (x-axis).

QUESTIONS:

1. Why is it useful to collect data from more than one trial at a particular temperature?

It is useful to do more than one trial at a particular temperature because results could vary every time due to various factors, such as small changes in temperature, the amount of time spent and intensity of 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. How did you make use of the properties of a saturated solution at different temperatures?

Since we knew that succinic acid is a solid solute and not a gas, we entered the procedure with the awareness that when the temperature of the water was risen, the solubility of the succinic acid should have risen as well. Although we did not run into the situation of solubility decreasing when the temperature was risen, if we had, this knowledge would have kept us from continuing the procedure with false data. Knowing that a supersaturated solution, if disturbed and cooled, rebalances itself and loses extra solute particles, it was interesting to see how many solutes sank to the bottom of the test tubes when the tubes were put in ice baths.

3. Did all the succinic acid that originally dissolved in the water crystallize out of the solution? Provide evidence to support your answer.

Yes, by cooling the clear solution in an ice bath after separating it from its original test tube and then allowing it to sit in room temperature for five minutes, we re-crystallized all of the succinic acid that originally dissolved in the heated water. By doing this, we were able to see the solubility of the succinic acid in each given temperature.

4. Given pooled class data, did you have enough data points to make a reliable solubility curve for succini acid? Would the curve be good enough to make useful predictions about succinic acid solubility at temperatures you have not yet investigated? Explain your answer.

No. Only two of the groups, The Metals and The Acids, actually completed the experiment with solubility data for each temperature. Because of this, we were only able to use these groups to average class data, even though there are many groups in the class. The curve we constructed only included the averaged data of these two groups; therefore, the curve we made would not be good enough to make useful predictions about succinic acid solubility at temperatures we have not yet investigated.

5. What procedures in this investigation could lead to errors? How would each error affect your data?

A huge error many groups made was putting the solute in the original test tube, and not the separated liquid, into the ice bath. This made these groups unable to complete their data tables. Also, 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 factors that would lead to errors and inaccurate data.

6. Using your knowledge of solubility, propose a different procedure for gathering data to construct a solubility curve.

A different procedure for gathering data to construct a solubility curve would be to take a substance and pour it into a beaker filled with water while mixing it at a given temperature. Once the water became a saturated solution, one would record the data, increase the temperature of the water, and repeat the procedure.