space.template.3.Lab3.Molecular+Substances

=Nonpolar Substances=

Previously we have determined the solubility of ionic substances in water. Ionic substances are substances in which the atoms are held together in an ionic bond. Meaning that one atom, the cation, will donate an electron to the anion. Take Potassium Chloride (KCl), for example. The Potassium (K), will donate an electron to the Chlorine atom (Cl) making it a Chloride Ion. Cations are usually metals and Anions are usually nonmetals. Ionic compounds dissolve in water

There are also molecular substances that are not ionic that dissolve in water as well. These substances dissolve, but unlike ionic compounds do not form ions in the water. What determines the solubility of these molecular susbtances in water? The solubility is determined by their attraction to the water molecules verses their attraction for each other.

Most molecular substances are held together by the attraction of the positively charged nucleus to the negatively charged electron cloud. If the attraction is strong enough, the electrons may leave an atom to form an ion. Otherwise, the atoms will share the electron and form what is known as covalent bonds. Electronegativity is the ability for an elements atoms to attract shared electrons. In other words, how likely is it that the atoms will be able to attract electrons.

When one atom in a molecule is more electronegative than the other, it tends to pull the electrons closer to it, creating a dipole, or a polar molecule. Water is a good example of a polar molecule. Molecules with atoms that have large differences in their electronegativity tend to be polar. Polar solutes tend to dissolve in polar solvents. Since water is a polar solvent, it will be a good way to test to see if certain substances are polar/ionic or nonpolar. A nonpolar substance is one that does not have a great difference in electronegativity. These substances tend not to dissolve in water.

The objective of your lab activity today is to design an experiment testing the following materials to see if they are nonpolar substances. salt, sugar, sugar substitute, canola oil, vegetable oil, and pump light oil

Prelab
1.) Cations are usually .................... and Anions are usually ......................... . 2.) What is an elements electronegativity determine? 3.) When one atom in the molecule is more electronegative than the other, what type of molecule is formed? 4.) Are nonpolar substances likely to dissolve in water? 5.) Predict which of the following substances are nonpolar substances: salt, sugar, sugar substitute, canola oil, vegetable oil, and lamp oil.

Procedure Write a procedure on how you will test each substance to determine if it is nonpolar.

Data

 * Substance || Nonpolar (yes or no) ||
 * salt (NaCl) ||  ||
 * sugar (C6H1206) ||  ||
 * sugar substitute ||  ||
 * canola oil ||  ||
 * vegetable oil ||  ||
 * pump light oil ||  ||

Analysis
1.) Which substances did you determine to be nonpolar and why do you feel that this is so? 2.) What do the nonpolar substances have in common? 3.) Using your periodic table, can you identify at least one substance above that might be an ionic compound? 4.) Can you think of any other susbtances that might be nonpolar? 5.) Certain types of paint such as oil paint does not typically dissolve in water and you need a paint thinner to remove it. Can you guess as to why that is necessary?

Conclusion
Was your hypothesis correct? (Restate your hypothesis) Was there any sort of error in the lab that could have effected your results. List three things that you learned from this lab.