



Study with the several resources on Docsity
Earn points by helping other students or get them with a premium plan
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Community
Ask the community for help and clear up your study doubts
Discover the best universities in your country according to Docsity users
Free resources
Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors
An experiment aimed at determining the physical properties of unknown organic compounds, including their solubility, density, melting point, boiling point, and refractive index. The experiment involves using various solvents and techniques to measure these properties, which can help identify and determine the purity of the compounds. The document also includes a list of possible solids and their solubility in different solvents, as well as a procedure for conducting the experiment.
What you will learn
Typology: Lecture notes
1 / 5
This page cannot be seen from the preview
Don't miss anything!
Physical properties are defined as a property that can be measured without changing the composition of the substance. The physical properties that will be measured during this lab are solubility, density, melting point, boiling point and refractive index. These physical properties can help elucidate the identity of an unknown substance. These same properties can also be used to determine the purity of a particular compound. Let us look at each of these properties individually.
Solubility is defined as the maximum mass of a substance that can be dissolved in a fixed mass of a solvent at a given temperature. A substance will have a different solubility in different solvents depending on polarity of both the substance and the solvent. The old adage is that like dissolves like, hence a polar substance will be more soluble in a polar solvent and vice versa. The solvents used in this experiment will be water, ethanol, acetone and benzene.
Density is defined as the mass of a substance per a unit volume. In this experiment, grams per milliliter will be the density units. A dense liquid such as mercury has a density of 13.546 g/mL. In contrast, hexane has a density of only 0.659 g/mL. Hence, one can use the density in determining the identity of an unknown substance.
The melting point is defined as the temperature at which a substance goes from a solid to a liquid. For example, water (ice) changes from a solid to a liquid at 0 Celsius at STP. Although the melting point is usually listed at a certain temperature, most substances melt over a temperature range. The temperature range is defined as the temperature at which a substance begins to melt to the temperature at which the whole sample is completely a liquid. A smaller temperature range would indicate a purer substance.
The boiling point is defined as the temperature at which a substance goes from a liquid to a gas. For example, water changes to steam at 100 Celsius at STP. However, unlike the melting point, boiling points are significantly affected by atmospheric pressure.
The refractive index can also be used to determine the identity of an unknown substance. Refraction is the changing in the direction of a ray of light passing from one medium to another. You have probably observed this looking down into the water while standing in it. The refraction of light causes you legs to look shorter. As with the other physical properties, a substance has unique refractive index.
Acetamide soluble soluble Acetanilide soluble soluble soluble Anthracene soluble^ soluble Benzoic Acid soluble soluble soluble Benzoin soluble soluble
List of possible liquids 1-propanol 2-propanol 2-butanol 2-methyl-1-propanol 3-methyl-1-butanol ethyl acetate toluene
Melting Point
Determine the melting point of your unknown solid
Solubility Determine the solubility of your unknown solid in water.
Refractive Index
Determine the refractive index of your unknown liquid. Correct use of the refractometer will be demonstrated by your laboratory instructor.
With the data you have collected for the density, boiling point and refractive index determine the identity of your liquid unknown.
Data Name____________________
_Solid Unknown #_____________________
Solubility
Water observations:
Ethanol observations:
Acetone observations:
Benzene observations:
Melting Point
Temperature where solid begins to melt: ____________________
Temperature where solid is completed melted: ____________________
Identity of unknown solid: ____________________
_Liquid Unknown #_____________________
Density
Mass of 1 mL of unknown liquid: ____________________
Density of unknown liquid: ____________________ (Show calculation)
Boiling Point
Temperature of boiling point: ____________________
Refractive Index: ____________________
Identity of unknown liquid: ____________________