Essay about Idenitfication of Substances by Physcial Properties

1139 Words Oct 20th, 2012 5 Pages
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.

Being able to identify unknown substances by observing their
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3. Clamp the test tube to the Ring stand and place onto the hot plate. 4. Heat the water and watch for changes. 5. The temperature will become constant at the boiling point of the liquid. 6. Record the observed boiling point.

Using the Refractometer

1. Remove the black cover exposing the sample well 2. Check that it is dry 3. Add the unknown sample to the well so that the entire surface of the well is covered 4. Replace the black cap and press Measure. 5. The instrument will equilibrate the sample and run the refractive index. 6. Record the value

Results A. Solubility | Water | Cyclohexane | Alcohol | Naphthalene | I | S | SP | Toluene | I | S | S | Liquid unknown | S | S | S | Solid unknown | S | SP | I |

B. Density
Final volume of liquid in cylinder | 6.6 mL | Initial volume of liquid in cylinder | 5 mL | Volume of solid | .6 mL | Mass of solid | .998 g | Density of solid 1.6 g/mL Liquid Volume of liquid | 10 mL | | | Mass of 50-mL beaker plus 10-mL of unknown | 46.669 g | Mass of 50-mL beaker | 38.995 g | Mass of liquid | 7.67 g |

Density .767 g/mL C. Melting point of solid unknown Observed melting point | 58 C | Corrected | | Observed melting-point range | 58-69 C | Corrected | |

D. Boiling point of liquid Unknown Observed | 85 C | Corrected | | Estimated true b.p. | |


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