Orgo I Lab Report 1 PDF

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This is the lab report for experiment number 1 of organic chemistry I lab. I received a 38/40 on this because the TA would have liked a more elaborate discussion, but the rest was good. ...

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Experiment 1 Simple and Fractional Distillation of a Binary Mixture Manoela Cunha

Introduction

There are numerous ways to separate liquids that were mixed together. One of these methods is called distillation and involves boiling off one of the liquids into a gaseous state. When doing distillation, it is important that both liquids do not boil off, or the product collected in the end would be impure. The boiling point of a liquid is the temperature at which the vapor pressure is equal to the atmospheric pressure. Under this condition, heat is added to the liquid and transforms it into vapor, without raising the temperature. Vapor pressure is the point at which the liquid reached equilibrium pressure between molecules leaving liquid and going into the gaseous phase or vice versa (Stimson, 1969). Simple and fractional distillation is used to purify or separate a mixture of liquids through the use of heat. Simple distillation is used to separate liquids, the mixture is boiled, and the compounds with the lowest boiling point will be vaporized and the condensation is stored. Fractional distillation is used to separate liquids with boiling points with less than 10 °C of difference. The setup for fractional distillation is the same, however, there is a fractionating column for more efficiency (Pabasara, 2017). Raoult’s Law describes that once a substance is mixed, the overall vapor pressure will decrease due to crowding in the solution. Raoult’s Law explains why even if solvents have slightly higher or lower boiling points, they may evaporate at the same time as other solvents. Dalton’s Law of distillation further explains that the total pressure in the setup would be equal to the number of both solvent’s vapors (Anne Marie Helmenstine). P solution = X solvent P 0 solvent The boiling point of Cyclohexane is 81°C, which is much lower than Toulene at 111°C. The difference in boiling points makes it relatively easy to boil Cyclohexane from Toluene and

separate the liquids. Azeotropes are sometimes formed from the mixing of two compounds, creating compounds that boil at the same or similar times and become impossible to separate from each other. Experimental Section

Table of Chemicals

Chemical

Molar mass

Name and

(g/mol)

Boiling Point

Melting Point Chemical Shape

Formula Cyclohexane

(Chem-Draw) 84.16

81°C

6.47°C

Highly flammable, Causes skin irritation, dizziness, Can be fatal if swallowed, Follow proper hygiene procedures and wear personal protective equipment.

92.14

111°C

-95°C

Highly flammable, May be absorbed through the skin, Possible harm to unborn child, Causes liver and kidney damage, Follow proper hygiene procedures and wear personal protective

C 6 H 12

Toluene C 7H 8

SDS

equipment.

Results Simple Distillation Cyclohexane Volume of distilled cyclohexane = 3.1mL

Temperature (°C)

Np. of drops

Volume (mL)

60

0

0

62

3

0.1

62

6

0.2

63

9

0.3

64

12

0.4

64

15

0.5

66

18

0.6

67

24

0.8

68

30

1.0

70

36

1.2

72

45

1.5

73

51

1.7

74

57

1.9

76

66

2.2

76

72

2.4

78

78

2.6

79

81

2.7

80

87

2.9

80

90

3.0

81

93

3.1

Percent Recovery (Simple Distillation of Cyclohexane)

(Actual Recovery/Theoretical Recovery)*100 (3.1 / 3.5) * 100 = 88.57% Yield

Toluene Volume of distilled Toluene = 3.2mL

Temperature (°C)

Np. of drops

Volume (mL)

Total Volume (mL) (Cyclohexane +Toluene)

90

3

0.1

3.2

91

6

0.2

3.3

92

9

0.3

3.4

94

12

0.4

3.5

96

18

0.6

3.7

97

21

0.7

3.8

99

24

0.8

3.9

100

30

1.0

4.1

101

33

1.1

4.2

102

36

1.2

4.3

103

45

1.5

4.6

103

54

1.8

4.9

104

57

1.9

5.0

105

66

2.2

5.3

106

69

2.3

5.4

108

78

2.6

5.7

108

84

2.8

5.9

110

90

3.0

6.1

110

93

3.1

6.2

111

96

3.2

6.3

Percent Recovery (Simple Distillation of Toluene)

(Actual Recovery/Theoretical Recovery)*100 (3.2 / 3.5) * 100 = 91.43% Yield

Fractional distillation Cyclohexane Volume of distilled cyclohexane = 3.2mL

Temperature (°C)

Np. of drops

Volume (mL)

62

0

0

63

3

0.1

63

6

0.2

64

9

0.3

65

15

0.5

66

18

0.6

68

24

0.8

68

30

1.0

70

39

1.3

71

45

1.5

72

51

1.7

74

54

1.8

74

60

2.0

75

66

2.2

76

69

2.3

78

78

2.6

79

84

2.8

80

90

3.0

80

93

3.1

81

96

3.2

Percent Recovery (Fractional Distillation of Cyclohexane)

(Actual Recovery/Theoretical Recovery)*100 (3.2 / 3.5) * 100 = 91.43% Yield

Toluene Volume of distilled Toluene = 3.1mL

Temperature (°C)

Np. of drops

Volume (mL)

Total Volume (mL) (Cyclohexane +Toluene)

94

3

0.1

3.3

95

6

0.2

3.4

95

9

0.3

3.5

96

12

0.4

3.6

98

15

0.5

3.7

99

18

0.6

3.8

101

24

0.8

4.0

103

30

1.0

4.2

104

33

1.1

4.3

105

42

1.4

4.6

105

48

1.6

4.8

106

54

1.8

5.0

106

63

2.1

5.3

107

69

2.3

5.5

108

75

2.5

5.7

108

81

2.7

5.9

109

87

2.9

6.1

109

90

3.0

6.2

110

93

3.1

6.3

Percent Recovery (Fractional Distillation of Toluene)

(Actual Recovery/Theoretical Recovery)*100 (3.1 / 3.5) * 100 = 88.57% Yield Discussion The percent yield of Cyclohexane and Toluene for recovery during Simple Distillation was 88.57% and 91.43%, respectively. This indicated that Toluene had a higher percentage of recovery. However, the percent yield of Cyclohexane during Fractional Distillation was 91.43% and the percent yield of Toluene was 91.43%. The results show that Fractional Distillation was more effective when distilling Toluene, while Simple Distillation was more effective for Cyclohexane. The graphs follow the same trend and look linear, with a constant increase in the number of drops and volume as the temperature increases.

Conclusion The objective of the lab was to distill two liquids mixed together in order to obtain the pure liquid. This was achieved throughout the lab and was successful according to the high rates of percent yield for both Cyclohexane and Toluene. Understanding the difference between simple and fractional distillation was useful when analyzing the data and investigating the effectiveness of each method under different conditions. From the background of the experiment, it is recommended that simple distillation is the most effective method for separating Cyclohexane and Toluene since the difference between their boiling points is around 30°C. Distillation has many uses in the real world. One example is separating rainwater from mud in order to generate pure drinking water. Separating water from salt through boiling is also a way to use distillation, and in this case, fractional distillation is the recommended method.

When analyzing the percent yield and successful separation of the two compounds, the experiment did accomplish what it was set out to do.

References

Anne Marie Helmenstine, P. D. What Is Raoult's Law? ThoughtCo . Pabasara. (2017, February 27). Difference Between Fractional Distillation and Simple Distillation: Process, Apparatus, Uses. Pediaa.Com. Stimson, H. F. (1969) Some Precise Measurements of the Vapor Pressure of Water in the Range From 25 to 100 °C. Journal of research of the National Bureau of Standards. Section A, Physics and chemistry. National Institute of Standards and Technology....