Classification of Solids

The purpose of this lab was to identify the properties common to a particular class of solid, classify a solid substance by its propoerties, and to develop lab techniques to check the melting point, conductivity, solubility, and observe the gross properties of a solid substance.

We used our knowledge of chemical bonding to understand how the intermolecular forces within a solid affect its properties. With our results then, we were able to classify different solids into different categories.

We started by obtaining samples of MgO, CoCl2 * 6H20, phenyol saline acid, benzoic acid, charcoal, sand, iron and zinc into plastic well plates. We observed and recorded the crystals present in each of the samples. Then we tested the melting point by putting a small sample of each substance into test tubes and heating them with a Bunsen burner. We recorded the approximate melting point into a data table classified by less than 100 degrees, between 100 to 300 degrees, and greater than 300 degrees. Next, we tested the solubility. After organizing each substance into three small samples in two different well plates, we then obtained distilled water, ethanol, and cyclic acid (under the fume hood). We put about 20 drops of each liquid into the three samples of each substance and recorded if "all," "some," or "none" of the solid dissolved in the liquid. If all of the solid dissolved in the water, we tested its conductivity. Only the cobalt chlorine and potassium bromide were positive in conductivity.

Classification:

Molecular Solid                    Ionic Solid                   Metal                       Network Solid

Phenyl Saline                          MgO                            iron                            charcoal

benzoic acid                            CoCl2                         zinc                               sand

                                               KBr

Questions:

1. A) ionic solids

    B) (skipped)

   C) molecular solids

   D) metals

   E) molecular solids

2. This solid would be classified as a molecular solid because it has a very low melting point and has slight (not complete) conductivity. 

3. This solid would be classified as a network solid because it was a very high melting point, it is insoluble in all solvents, and does not conduct electricity. 

4. A) K- metal 

    B) CaCo3- ionic solid

    C) C8H18- molecular solid

    D) HCl- ionic solid

5. A) Network solids are generally insoluable in water

    B) Metals are generally ductile and malleable. 

    C) Ionic solids are generally nonvolatile. 

6. The melting point test did not seem to work too well because we could not precisely determine the temperature in which a substance started to melt. Also the solubility test because the cyclic acid reacted with the plastic well plates.