Chemical compounds are combinations of atoms held together by chemical bonds. These chemical bonds are of two basic types—ionic and covalent. Ionic bonds result when one or more electrons from one atom or group of atoms is transferred to another atom. Positive and negative ions are created through the transfer. In covalent compounds no electrons are transferred; instead electrons are shared by the bonded atoms. The physical properties of a substance, such as melting point, solubility, and conductivity, can be used to predict the type of bond that binds the atoms of the compound. In this experiment, you will test six compounds to determine these properties. Your compiled data will enable you to classify the substances as either ionic or covalent compounds.
OBJECTIVES
Compare the melting points of six solids.
Determine the solubilities of the solids in water and in ethanol.
Determine the conductivity of water solutions of the soluble solids.
Classify the compounds into groups of ionic and covalent compounds.
Summarize the properties of each group.
MATERIALS
|24-well microplate |aluminum foil square |
|Bunsen burner |thin-stemmed pipets (2) |
|conductivity tester |CaCl2 (calcium chloride) |
|ethanol |KI (potassium iodide) |
|iron ring |NaCl (sodium chloride) |
|ring stand |C13H18O2 (ibuprofen) |
|thermal gloves |C8H9NO2 (acetaminophen) |
|lab apron