Shahin Avokh-lab report 2 PDF

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Shahin Avokh Lab 2 Separation of Liquids by Simple and Fractional Distillation

Methods and Background

The purpose of this lab was similar to our last lab. However, this time we separate compounds base on their boiling point instead of polarity. In this lab, we had on a half and half mixture of acetone and 1-propanol and separating them using fractional and simple distillation method and then operating our collected samples through a gas chromatograph to validate our results.

The types of intermolecular forces between these two molecules are critical to their boiling points. In acetone, only intermolecular forces present are dipole-dipole interactions, which are lighter than the H-bonding that 1-propanol maintains. This explains that acetone has a lower boiling point at 48 C and 1- propanol has a boiling point of 97 C. based on this information, we believe to see acetone evaporate first when we are heating the mixture and be the primary solution, we collect in our first fraction. In the second fraction, we would expect to see a 50:50 ratio of both acetone and 1-propanol. However, in our last sample, we expect to get only 1-propanol because of acetone should have been steamed already.

This lab divided into two parts. First, simple distillation and second, fractional distillation. In simple distillation we distilled the 50:50 ratio at about one drop and every drop's temperature recorded. After we noticed a reasonable unusual rise in T mL, like a jump in a couple of C degree, we collected that fraction. We repeated these two more times to

maintain a total of 3 fractions for practically the start, middle, and end of the distillation process.

We operated the three samples through gas chromatography and printed three graphs which presented the ratio of each molecule contained in the specific fractions.

For the second part of this lab, fractional distillation, we did the same procedure as we did with simple distillation however we adopted a fractionating column filled with glass or plastic dots which allows the liquid to steam and condense over and over again, therefore, providing for more accurate fractional samples. Fractional distillation gives more precise results because the stones allow the liquids to distill over before even dropping out of the column and getting in our beakers.

The retention time was how long it takes to move through the chromatography column during GC. During simple distillation, it took about 30 sec for the first peak to appear, 50 seconds for the second peak to appear and about 65 seconds for the third peak to come. During fractional distillation, the retention times were shorter, taking about 20 seconds for the only peak to appear. Fractional distillation is more accurate, and it takes less to separate the bands or the molecules in order to graph them out since fraction one and three are one molecule. The other thing that effect retention time is the length of the column. If we used a smaller column, the retention time is shorter.

The gas chromatographic machine in which we entered our fractions through, uses a method in which a gas source drives the sample through the machine once it enters the injection section. The injection block evaporates our sample and is now running through to the column, which separates them into bands that pass through a detector which sends the results to the recorder and then gives us the gas chromatograph. There are few things that can

affect the resolution of the results the gas chromatograph. fist is the length and diameter of the column. A longer column with a smaller diameter gives better resolution and separation of bands. Temp of the column can change band separation results, as well as the flow rate of the carrier gas being used. The results from the gas chromatograph showed which molecule fractions contained the most of based off of the area under the curve. For example, our first fraction we expected to be purely acetone because of acetone's lower boiling point. After running it through gas chromatograph, we ended up with a chromatograph displaying two curves, the one furthest to the left side having the greater area, with about a 2.7:1 ratio of acetone to 1-propanol. The second fraction we ran through we found two curves with about equal acetone to 1-propanol ratio, as expected. And the last fraction we ran through we found the curve considerably to the right to have the most area, being 1-propanol.

Experimental Procedure

We started by setting up the distillation glass by doing a round flask filled with solvent and a boiling rock inside it, putting this over a hotplate and to the top of the flask we added a column for simple and fractional method, with a rubber stopper and a thermometer inside it. then joined the condenser with hoses for the water flowing in and out, and finally the graduated beaker we used to collect the fractions mL by mL to report the temperature.

After setting up the glasswork, the evaporator was turned on and waited for the solution to begin evaporating and moving to the condenser and dripping out into our graduated cylinder. At about 40-50 C for the fractional column, we started to notice the solution dropping out. After 1mL of solution we obtained we noted the temperature and did that until all 30mL of solution had steamed.

During the lab we saved note of any unusual increases in temperatures between each mL and after a significant rise we set that portion of solution aside and marked it as a fraction. We did these three different times to collect three different fractions for the gas chromatograph.

After getting three different fractions for both fractional and simple distillation, we took them to the gas chromatograph and added a small volume of each sample into the injection block and recorded the results on the computer. We printed the graphs and analyzed it. then moved on to calculations

.

Data Acquisition

Acetone: molecular formula: C3H6O, molecular weight: 55.08 grams/mol, boiling point: 55-56 degrees Celsius

1-propanol: molecular formula: C3H8O, molecular weight: 60.10 grams/mol, boiling point: 96-97 degrees Celsius.

Fractional distillation

Simple distillation

Volume (mL) of fraction 1

12mL

11mL

Volume (mL) of fraction 2

2mL

11mL

Volume (mL) of fraction 3

10mL

4mL

Mol% acetone in fraction 1

100%

78.5%

Mol% 1-propanol in fraction 1

0%

21.5%

Mol% acetone in fraction 2

23%

59.5%

Mol% 1-propanol in fraction 2

77%

40.5%

Mol% acetone in fraction 3

0%

0.002%

Mol% 1-propanol in fraction 3

100%

99.998%

Mol % calculation for fractional distillation: Fraction one: Peak one: area=606.3(from graph), mol%: (606.3/606.3)x100=100% meaning 100% acetone since there was only one peak Peak two: area=0 meaning mol%=0 as well since 100% of sample was acetone v Fraction two: Peak one: area=46.30 (from graph), mol%: ((46.30x1.17)/(46.30x1.17) +(150.4x1.20))x100 =23%. (1.17 is the mole correction factor for acetone and 1.20 for 1-propanol) Peak two: area= 150.4 (from graph), mol%: ((150.4x1.20)/(46.30x1.17) +(150.4x1.20))x100= 77% Fraction three: Peak one: area=0 meaning mol%=0 as well since 100% of sample was 1-propanol

Peak two: area=198.1mvs (from graph), mol%: 198.1/198.1x100=100% meaning 100% of the sample was 1-propanol. Mol% calculations and area of simple distillation: Fraction one: Peak one: mol%: ((7701x1.17)/ (7701x1.17) +(2050x1.20))x100=78.5% Acetone Peak two: mol%: ((2050x1.20)/(2050x1.20) +(7701x1.17))x100=21.5% 1-Propanol Fraction two: Peak one: mol%: ((5018x1.17)/ (5018x1.17) +(3331x1.20))x100=59.5% Peak two: mol%: ((3331x1.20)/(3331x1.20)+(5018x1.17))x100= 40.5% Fraction three: Peak one: mol%: ((16.69x1.17)/(16.69x1.17) +(7371x1.20))x100=0.002% Peak two: mol%: ((7371x1.20)/ (7371x1.20) +(16.69x1.17))x100=99.998% \

Simple distillation

Temperature (Celsius) Volume (mil liters)

57

1

58

2

58

3

59

4

59

5

60

6

60

7

60

8

60

9

60

10

60

11

65

12

69

13

74

14

75

15

75

16

89

17

90

18

90

19

90

20

90

21

90

22

90

23

90

24

90

25

90

26

Fractional distillation

Temperature Volume (mL) (Celsius)

55

1

56

2

54.5

3

55

4

55

5

55.5

6

56

7

56.5

8

57

9

58

10

58.5

11

64

12

92

13

93

14

93

15

93.5

16

93.5

17

93.5

18

94

19

94

20

94

21

94

22

94

23

Conclusion our goal was to distribute compounds based on different boiling points using simple and fractional distillation. the boiling points of the two liquids in the mixture were conducted online, and concluded that acetone had a lower boiling point so we would anticipate to see acetone evaporate first and 1-propanol vaporize last. in the middle of the first and last fraction we have a fraction with about a 50:50 blend of the two.

After we collected three separate fractions for both methods, we took them over to the gas chromatograph and put them on the system. Our results were as anticipated. for simple distillation, the first fraction we obtained, we saw two hills in which the left peak had a bigger area of 7701mvs to the right which had an area of 2050mvs, indicating that we got more acetone than 1-propanol which make sense. acetone has lower boiling point and would evaporate first. For the second fraction we obtained we saw kind of same area in both the peaks, with acetone at 5018mvs and 1-propanol at 3331mvs, also shows the fact that at the midpoint of the distillation process we see about a 50:50 proportion of both acetone and 1propanol. The last fraction we obtained showed a greater 1-propanol peak with an area of 7371mvs and a significantly smaller acetone peak at 16.69mvs. This shows that the rest of the 1-propanol was vaporized after reaching past it’s boiling point temperature. next, for fractional distillation, the first fraction we collected ranked 100% acetone with only one peak of wholly acetone. For the second fraction we found about a 25:75 ratio of acetone and 1propanol, with an acetone area of 46.30mvs, and for 1-propanol 150.4mvs. we expected to get a 50:50 ratio, but the break between our lab which was because of fire drill might affected our data. for the third fraction we observed only one peak of solely 1-propanol. The fractional distillation more precisely presented the results, that’s because of the various columns used in the machinery. The fractionating column filled with the beads allowed for the solution inside to steam over before actually eluting out of the column and gathering in the beaker....