Melting Point Determination

OBJECTIVES

1. To determine the identity of an unknown by its melting point.

2. To confirm the identity of an unknown by using the mixed melting point technique.

MATERIALS

8 Known chemicals with literature melting points.

Name of Known Lit. M.P. Name of Known Lit. M.P

Adipic Acid 151Ð'Ñ"c - 153Ð'Ñ"c Resorcinol 109Ð'Ñ"c - 110Ð'Ñ"c

Citric Acid 152Ð'Ñ"c - 153Ð'Ñ"c Toluic Acid 110Ð'Ñ"c - 112Ð'Ñ"c

Naphthalene 80Ð'Ñ"c Phenyl acetic Acid 77Ð'Ñ"c - 78Ð'Ñ"c

Phenacetin 134Ð'Ñ"c-135Ð'Ñ"c Urea 133Ð'Ñ"c - 134Ð'Ñ"c

EQUIPMENT & APPARATUS

Meltemp Apparatus: Heating block used to melt chemicals at unknown temperatures.

Capillary tubes: Tubes used to hold chemicals to be melted.

Thermometer: Used to determine the temperature at which chemicals melt.

Watch glass: Used to hold chemicals and for transfer of chemicals into capillary tubes.

Hollow glass: Used to contain capillary tubes and to help pack the chemicals into the tube.