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Experiment #2 Kayla Morren Identifying an Unknown Substance Objective: Based on solubility, density, boiling point, and/or melting point, to utilize these physical properties in order to identify and an unknown solid and an unknown liquid. This experiment is conducted in order to determine which precise substance these unknown substances are and to hope to learn how to determine these using physical properties solely.

Introduction: Chemical properties can be observed when a substance changes its chemical identity into another substance. Physical properties is an aspect of a substance that can be measured or observed without changing the substance itself. Utilizing these physical properties can help in order to determine what a substance is. Examples of physical properties are density, melting point, boiling point, solubility and state of matter. Density is determined by mass divided by volume. Solubility is determined by dissolving the solute within the solvent, which in this experiment is water and ethanol. Melting Point and Boiling Point are determined through tests involving boiling water, a thermometer and more which are explored throughout this experiment.

Substance

Density (g/mL)

Melting Point (℃)

Boiling Point Soluble in (℃) Water

Soluble in Ethanol

Calcium Carbonate

2.93

Dec 825

Dec

I

I

Calcium Nitrate

1.82

43

Dec

S

S

Cyclohexane

0.78

6.5

81

I

S

p1.46 Dichlorobenz ene

53

174

I

S

Diphenylmet hane

1.00

27

265

I

S

Ethanol

0.79

-112

78

S

S

Hexane

0.66

-94

69

I

S

Iodomethane

2.28

-66

42

Sl-S

S

Lauric Acid

0.88

48

225

I

S

Methanol

0.79

-98

65

S

S

Experiment #2 Kayla Morren 2-Propanol

0.79

-86

83

S

S

Propanone

0.79

-95

56

S

S

Stearic Acid

0.85

70

291

I

Sl-S

p-Toluidine

0.97

45

200

Sl-S

S

Trichloromet hane

1.49

-63.5

61

I

S

Results and Discussion:

Unknown

Melting Point

Boiling Point

Density

Soluble in Water

Soluble in Ethanol

Identity

Solid E

Dec 825℃

Dec

0.63g/mL

No

No

Calcium Carbonate

Liquid A

-112℃

78℃

0.762g/mL

Yes

Yes

Ethanol

Throughout our experiment, overall we determined that the outcome of the unknown solid was Calcium Carbonate and we determined that the outcome of the unknown liquid was Ethanol. In order to identify these unknown substances, first we determined their density in the units of grams over milliliters. By taking the mass on a scale of the weight of the tray with the substance on it minus the weight of the tray alone in order to determine the mass of the substance solely. Then we determined the volume by placing the substance into a graduated cylinder with water and using the displacement of the water at the meniscus in order to obtain the volume. Next, we tested solubility in both water and in ethanol. In order to determine solubility, the substance we place inside either water or ethanol must dissolve within it. With our unknown solid, it did not dissolve in both water or ethanol. With the unknown liquid, it dissolved in both water and ethanol. Also, we then obtained the boiling point of the water to further classify our unknown substances by taking a beaker filled with water and heating it on top of a hot plate. The unknown substance was placed within the boiling water inside a test tube with a thermometer inside it and a stirrer inside the boiling water. The boiling point was determined once the thermometer level was no longer rising and for the unknown substance we were not able to determine it exactly because it continued to rise above all the substances on the list provided except one which was unattainable through using just the thermometer. Our unknown liquids boiling point stopped at 78℃ . Referring to the chart using the different physical properties we had determined, we were able to conclude that the unknown solid was Calcium Carbonate and the unknown liquid was

Experiment #2 Kayla Morren Ethanol. For our unknown solid, there was no other possible substance it could have been although our density was off quite a bit but this possible error could be due to that we could not really determine an exact volume in that it barely moved once the substance was placed into the graduated cylinder so the volume was an estimate. For our unknown liquid, all of our physical properties were almost spot on to the information provided on the table for Ethanol. If we had let the thermometer stop before it reached its boiling point, we would have gotten another answer. ` Conclusion: Our objective was fulfilled as we determined which substance our unknown solid and unknown liquid were based on the utilization of their physical properties such as melting point, boiling point, solubility and density. In this experiment we learned how to determine unknown substances even without knowing what they are and identified our unknown solid as Calcium Carbonate and our unknown liquid as Ethanol.

References: El-Ashmawy, Amina Khalifa. “Identifying an Unknown Substance.” 2017.

Experiment #2 Kayla Morren...