Experiment 2

Solubility, Density, and Melting Point of Solids

Parts A, B, C, Unknown

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Purpose of This Experiment• Determine the solubility of a solid sample• Calculate the density of a solid sample• Determine the melting point (m.p.) of a solid with

the melting point apparatus• Determine the identity of an unknown by its

physical properties (solubility, density, m.p.)

• Work in groups of 2 for the known solid• Work individually for the unknown solid (lab partners must use different unknowns)

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Determination of Solubility• Use only a few crystals of solid

• Place the solid in the bottom of a small test tube, add the appropriate liquid, and shake back-and-forth gently

• If the solid dissolves, it is soluble (s) in the liquid. If the solid does not dissolve, it is insoluble (i) in the liquid. If the solid dissolves a little, but not completely, it is sparingly soluble (sp) in the liquid.

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Density Calculation

Density = mass / volume

Mass is found with the lab balance (find mass, then find volume of that mass)

Volume by difference

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Volume by Difference

• Technique used to find the volume of irregularly shaped solids

• Put enough liquid into a graduated cylinder, record volume (SF and units)

• Add solid sample (of known mass) to this graduated cylinder, record volume (SF and units)

• Calculate the volume of the solid(volume liquid and solid – volume of liquid = volume of solid)

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Melting Point Determination

• Use the melting point apparatus. Ask for help using the m.p. apparatus.

• Crush a few crystals of your sample on weighing paper with the bottom of a test tube. (Press firmly to crush.)

• Put crystals in a capillary tube, then you are ready to use the m.p. apparatus

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Identify Unknown

• Determine the density of the unknown solid.• Determine the solubility of the unknown solid.• Determine the m.p. of the unknown solid.

(as time permits, choose at least 2 from above)

• Identify the unknown solid from list using your determined physical properties.

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