Formal report 1 - chemistry PDF

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ID of substances by Physical properties

Vardhankumar Patel

Date of Experiment: February 16th

My document identifies all sources used and assistance received in completing this assignment. I promise to abide by the principles of academic integrity outlines in the Wake Tech syllabus for this class and in the student handbook. I understand that students found guilty of plagiarism or cheating will receive a grade of "0" (zero) on the work submitted, and the Dean of Students will be notified immediately. I did not use any sources or assistance requiring documentation in completing this assignment.

Name: Vardhankumar Patel Signature: Vardhankumar Patel

Purpose: The main purpose of this experiment was to identify unknown solids and liquids by evaluating some of its physical properties experimentally. Physical properties such as density, solubility, melting point, and boiling point. Method: For the first part of the experiment, in each test tube a few pea sized of the known solid was placed. After that water and ethanol was added to each test tube. Covering the test tubes with small square of parafilm the test tubes were shaken vigorously. The same process was repeated with the unknown solid this was done to done to determine the solubility of both solids. If the liquid is cloudy that indicates partial solubility and if there is a second layer formed, it indicates insolubility. The observations were recorded. Next to determine the density of the solids approximately 1.5g of the unknown solid was placed on a weigh paper folded diagonally and record the exact weight that is displaced on the balance. Using a graduated cylinder, about 5 ml of the solvent in which the unknown solid was insoluble. After recording the initial volume, the unknown solution was added into the cylinder, gently tapping the bottom of the cylinder the solid settled to the bottom. the final volume is then recorded. Next to determine the melting point of the solids, a small scoop of finely pulverized unknown solid was placed into an open capillary tube which was then gently compressed by tapping the pulverized solid inside the tube into one solid piece which is no longer than 5mm in the length. Then solid was placed into a capillary tube which was then with an open end put into the melting point apparatus in a slight distance between the microscope and the heating block. And then the temperature was measured at 2 different intervals. We repeated the same process with the known solid also. For the second part of the experiment, we placed a clean 50ml beaker on am analytical balance and recorded the mass with the beaker then added 10.00ml of the unknown liquid into the beaker and recorded the mass immediately. We then did the same steps to find the mass of the known liquid which led us to finding the density of the two liquids. Next to determine the solubility of the two liquids we used the same liquid that we used when we were finding the density. We placed about 1 ml

of the known liquid each into 2 separate test tubes, and to that we added 4ml of solvent (water to one and ethanol to the other) to the two test tubes. And trying to dissolve the liquid, if it turned cloudy that indicates partial solubility and if there is a second layer formed that indicates insolubility. We then recorded the observations. Lastly to determine the boiling point we first heated water in a beaker till it was boiling. After that we filled a test tube with 5 ml of the unknown liquid, and in that we placed a capillary tube with the open end down and we clamped both the test tube and thermometer (this was called the boiling point setup) carefully. Once the water started to boil, we placed the boiling point setup into the water (both the bulb of the thermometer and the test tube must submerge completely). To get the correct reading for the boiling point we heat the unknown liquid in the test tube that is in the boiling water. We then recorded then temperature when the unknown liquid enters up the capillary which meant that the boiling point had reached.

Observation and data: For the first part we recorded our observations from the solubility test. (See table 1) Then we recorded the masses of both the solids that were used to determine the density. (See table 2) We then recorded the initial melting point and the final melting point that were used to determine the average melting point for the solids. (See table 3) (first part is for solids) For the second part we recorded our observations from the solubility test. (See table 4) Then we recorded the mass of our liquid that we used to determine the density for the liquid. (See table 5) Lastly, we recorded the boiling point of our liquids. (See table 6) (second part is for liquids)

Table 1: Solubility results We can see from the results that salicylic acid and water are insoluble because it creates a second layer and the same applies to the unknown solids. But on the other hand, both the substances are soluble in ethanol. (see table 1)

Substance

Solubility

Solubility

Water

Ethanol

Insoluble

Soluble

Salicylic acid

Unknown solid

I nsoluble

Soluble

Table 2: Recorded masses to determine the density. We were already given the mass of the solids. We had to calculate the volume and then use that volume to calculate density.

Mass of solid (g) Volume of liquid (ml) Volume of Liquid and

Salicylic Acid 1.4467 5.56 6.56

Unknown Solid 1.38770 4.07 5.16

Solid(ml) Volume of solid ( cm3 ) Density of Solid (g/ cm 3 )

1.00 1.45

1.09 1.27

Table 3: melting point for solids Before the solid started to melt it was kind of moving like it was almost looked flaky. The flakes started to move when it reached that initial melting point then slowly there was liquid the bottom of the test tube. And then after some while the solid had completely melted. It was liquid, and we recorded the final melting point.. (see table 3) To find the average melting point we simply added the initial temp plus the final temp and dived the sum by two to get the average melting temp.

Initial Melting Point (°C) Final Melting Point (°C) Average Melting Point (°C)

Salicylic Acid 153.0 °C 163.0 °C 158.0 °C

Unknown Solid 118.0 °C 125.0 °C 121.5 °C

Table 4: Solubility results As we can see form table 4 that both 2-propanol and the unknown liquid are soluble in water and in ethanol. (see table 4)

Substance

Solubility

Solubility

Water

Ethanol

soluble

Soluble

soluble

Soluble

2-Propanol 10.00 29.8921

Unknown Liquid 10.00 29.8921

2-Propanol

Unknown liquid

Table 5: Density of liquids

Volume of Liquid (ml) Mass of the clean 50-ml beaker (g)

Mass of the Beaker and liquid

37.7488

38.8900

(g) Mass of Liquid (g) Density of liquids (g/ml)

7.8567 0.7857

8.9979 0.8998

Table 6: boiling point of liquids As we stated in the method, we recorded the temperature when the liquid goes up the capillary tube. 2- propanol

Unknown Liquid

83.0

77.0

Image of the thermometer

Boiling Point (°C)

Results: Calculations for density of solids in Table 2: To calculate the mass of the solid we measured the initial volume of the liquid without the solid then measured the volume again with the solid in liquid and found the difference between the two which was our volume. The formula we used is below. Volume of salicylic acid:

Volume of liquid∧solid−volume of liquid=volume of solid 3

6.56 ml−5.56 ml=1.00 cm

Volume of unknown solid:

Volume of liquid∧solid−volume of liquid= volume of solid 5.16 ml−4.07 ml=1.09 cm3 Then we used the mass of the solid and the volume that we calculated to find the density. We used this formula: Density for salicylic acid:

density=

desnity=

mass volume

desnity=

mass volume

1.4467 g 1.00 cm3 3

density=1.4467 g / cm

final density=1.45 g/cm3

Density of the unknown solid:

density=

1.38770 g 1.09 cm3

density=1.273119266 g /cm3 final density=1.27 g /cm3

(See table 2). Calculations for density of liquids in Table 5: To calculate the density, we had to find the mass of the water. We successfully determined the mass of water by first measuring the mass of and empty beaker and then measuring the beaker after putting in the liquid. We then subtracted the mass of the beaker that had liquid in it minus the mass of the beaker itself. (see table 5) Mass of 2-Propaol:

mass of beaker ∧liqiud−mass of beaker=mass of liquid 37.7488 g−29.8921 g=7.8567 g As of the unknown liquid:

mass of beaker ∧liqiud−mass of beaker=mass of liquid 38.8900 g−29.8921 g=8.9979 g

Then we used the density formula to calculate the density using the mass obtained and the volume of the liquid that was used Density of 2-propanal:

desnity=

mass volume

density=

7.8567 g 10.00 ml

density =0.78567 g / ml

final density=0.7857 g /cm3 Density of the unknown liquid:

desnity=

mass volume

density=

8.9979 g 10.00 ml

density=0.89979 g / ml final density=0.8998 g /cm3 (See Table 5).

To compare the results from the experiment for solids we used appendix F.1 that has the physical properties of solids. It includes the name of the compound, the density, the melting point, and its solubility. Appendix F.1 is referred at Table 7a in this report. Table 7a: Physical properties of solids

Compound Acetamide

Density (g/mL) 1.16

Solubility MP (°C) Water 81 s

Ethanol s

Adipic acid

1.36

152 s

s

Anthracene

1.28

216 I

I

Ascorbic Acid

1.65

190 s

p

Benzamide

1.08

127 s

s

Benzil

1.50

95 I

s

Benzoic acid

1.27

122 I

s

Benzoin

1.31

137 I

s

Benzophenone

1.09

49 I

s

Caffeine

1.23

238 p

I

Cholesterol

1.07

145 I

I

Citric Acid

1.67

153 s

s

Maleic acid

1.59

138 s

s

Mannitol

1.49

168 s

p

Naphthalene

1.15

80 I

p

Palmitic acid

0.85

62 I

I

Potassium alum

1.76

92 s

I

Saccharin

0.83

227 p

s

Salicylic acid

1.44

158 I

s

Sorbic acid

1.21

133 I

s

Sorbitol

1.28

111 s

s

Stearic acid

0.95

71 I

I

Succinic acid

1.57

184 p

s

Tartaric acid

1.76

173 s

s

trans-Cinnamic acid

1.25

133 I

s

Urea

1.34

135 s

s

Vanillin

1.06

82 p

s

Xylitol

1.52

95 s

s

To compare the results from the experiment for liquids we used appendix F.2 that has the physical properties of liquids. It includes the name of the compound, the density, the boiling point, and its solubility. Appendix F.2 is referred at Table 7b in this report. Table 7b: Physical Properties of liquids

Compound

Density (g/mL)

Solubility BP (°C)

Water

Ethanol

Methyl isopropyl ketone

0.80

92 p

s

Ethyl Acetate

0.90

77 s

s

Acetone

0.79

56 s

s

Ethanol

0.79

79 s

s

Methanol

0.79

65 s

s

1-Propanol

0.80

97 s

s

2-Propanol

0.79

83 s

s

2-Butanol

0.81

98 s

s

Heptane

0.58

98 I

p

Cyclohexane

0.78

81 I

s

2-butanone

0.81

80 s

s

Cyclohexene

0.81

83 I

s

Hexane

0.66

69 I

s

1-hexene

0.67

63 I

s

Pentane

0.63

36 I

s

Methyl acetate

0.93

57 s

s

tert-butyl acetate

0.86

98 p

s

isopropyl acetate

0.87

89 p

s

ethyl propionate

0.88

99 I

s

ethyl formate

0.92

54 s

s

propyl formate

0.90

81 p

s

isobutyl formate

0.89

98 s

s

isopropyl formate

0.88

68 p

s

Conclusion: The main objective of this experiment was to identify the unknown solid and the unknown liquid through its physical properties. We used the table 7a and 7b to help us identify the unknown solid and liquid. We could conclude that the unknown solid is Benzoic acid. Firstly, because the density we calculated matched exactly with benzoic acid density found in Table 7a. Secondly, because the average melting point, we calculated in our experiment is very close to the melting point of our unknown solid in fact it was only off by 0.5 degrees Celsius. Lastly, because both our unknown solid and benzoic acid were insoluble in water but soluble in ethanol. We could conclude that the unknown solid was benzoic acid based on the observation/results and Table 7b. We could conclude that the unknown liquid is Ethyl Acetate. Firstly, because the boiling point we recorded for our unknown liquid matches exactly with the boiling point of ethyl acetate. It is 77.0 degrees exactly. Secondly, because the density we calculated for our unknown liquid is very close to the density of ethyl acetate found in Table 7b. The density we calculated for the unknown liquid is 0.8998 g/ml and the density for ethyl acetate is 0.90 g/ml. lastly, because both the unknown liquid and ethyl acetate is soluble in water and ethanol. we could conclude that the unknown liquid was ethyl acetate based on the observation/results of the experiment and Table 7b.

References: 1. Wake Technical Community College: General Chemistry 1(CHM 151) Laboratory Experiments; Wake Tech: North Carolina, 2019 pp 28-34....