Idenitfication of Substances by Physcial Properties
Lab 2 Report- Identification of Substances by Physical Properties
The purpose of this lab was to see how certain substances; Naphthalene, Toulene, and and 2 unknowns (one liquid, one solid) react with 3 different solvents. To identify the two unknowns, testing needs to be done to find the density of both the liquid and the solid, determine the melting point of the solid, and the boiling point of the liquid. The Physical Properties of Pure Substances Table can then be used to compare the observed results with the accurate properties from the table. If testing is done correctly, accurate assumptions can be made to figure out what the unknown substances were.
Introduction
Being able to identify unknown substances by observing their physical properties is very thought provoking. By using such properties as melting point, boiling point, density, solubilty and refractive index of unknown substances identification is possible. Scientists have gathered and recorded data on the physical properties of pure substances for well over 100 years. It is these data tables that allow us to do experiments on unknown substances and make reasonable assumptions as to the correct substance being investigated. By using such physical properties as solubility, density, melting point, boiling point and refractive index results were narrowed down from 32 possible choices to just 1 or 2.
Procedure
Testing for solubility of Naphthalene (mothballs): 1. Add a few crystals of Naphthalene to 3 clean, dry test tubes. 2. Add 2-3 mL water to test tube #1, 2-3 mL cyclohexane to test tube #2, and 2-3 mL of ethyl alcohol to test tube #3. 3. Stir each test tube with separate mixing rods. 4. Record the results. S for soluble, SP for sparingly soluble and I for insoluble. 5. Repeat this experiment using the same 3 solvent: water, cyclohexane, and ethyl alcohol with the unknown solid and unknown liquid. 6. Record the results (refer to #4)
Determine the densities of
The purpose of this lab was to see how certain substances; Naphthalene, Toulene, and and 2 unknowns (one liquid, one solid) react with 3 different solvents. To identify the two unknowns, testing needs to be done to find the density of both the liquid and the solid, determine the melting point of the solid, and the boiling point of the liquid. The Physical Properties of Pure Substances Table can then be used to compare the observed results with the accurate properties from the table. If testing is done correctly, accurate assumptions can be made to figure out what the unknown substances were.
Introduction
Being able to identify unknown substances by observing their physical properties is very thought provoking. By using such properties as melting point, boiling point, density, solubilty and refractive index of unknown substances identification is possible. Scientists have gathered and recorded data on the physical properties of pure substances for well over 100 years. It is these data tables that allow us to do experiments on unknown substances and make reasonable assumptions as to the correct substance being investigated. By using such physical properties as solubility, density, melting point, boiling point and refractive index results were narrowed down from 32 possible choices to just 1 or 2.
Procedure
Testing for solubility of Naphthalene (mothballs): 1. Add a few crystals of Naphthalene to 3 clean, dry test tubes. 2. Add 2-3 mL water to test tube #1, 2-3 mL cyclohexane to test tube #2, and 2-3 mL of ethyl alcohol to test tube #3. 3. Stir each test tube with separate mixing rods. 4. Record the results. S for soluble, SP for sparingly soluble and I for insoluble. 5. Repeat this experiment using the same 3 solvent: water, cyclohexane, and ethyl alcohol with the unknown solid and unknown liquid. 6. Record the results (refer to #4)
Determine the densities of
Citations: Lab handout- Identification of Substances by Physical Properties. Report sheet- Identification of Substances by Physical Properties.