Unknown Compounds

This lab investigated the relative melting points, solubility, and conductivity of three unknown compounds, A, B, and C. The purpose of this lab was to determine whether the compound was ionic by looking at the three physical properties of these unknown compounds. The three physical properties were recorded differently for each unknown compound depending on the reaction of the compound with the procedures that were taken. The relative melting points were found by placing a small amount of each compound onto a glass slide that had been split into three sections with their respective letters, placing the slide on a hot plate, and recording the order in which the compounds melted. The solubility of the compounds were found by placing a few crystals

Throughout the experiment, the following hypothesis was supported, as the compound that melted only slightly, and completely dissolved in water was determined to be an ionic compound. It was determined that Unknown Compound A was a polar covalent compound, because it was the only one that dissolved in water completely and it was not conductive, which are two traits that a polar covalent compound has. Polar covalent compounds are able to dissolve in water because, simply, the compound is polar, just like water. On the other hand, nonpolar compounds are not able to dissolve in water, because of the differing polarities. Polar covalent compounds, as well as nonpolar covalent bonds are not conductive, because they have no ions to conduct electricity. Ionic compounds are conductive because they have ions. It was discovered that Unknown Compound B was an ionic compound, because it melted the last of the three, was the best conductor, and dissolved in water. Although Unknown Compound B only slightly dissolved in water, the melting point and conductivity proved that it was an ionic compound. Ionic compounds have the highest melting points because the bonds in the compound are incredibly strong. A substantial amount of energy is needed to break those ionic bonds. This is in contrast to covalent compounds, where their bonds aren’t as strong, so only a low melting point is required to break the bonds. Ionic compounds also are conductive when dissolved in water because the ions are only able to conduct electricity when they are free to move. It was found that Unknown Compound C was a nonpolar covalent compound because it melted the first, did not conduct electricity, and did not dissolve in water. Covalent compounds have low melting points, because the bonds are not very strong, and only a small amount of energy is needed to break them. Covalent compounds also do not