DO NOT WRITE ON THIS LAB!!!!
LAB # _______
Lab Instructions – Polar Water
Purpose: to examine the relationship between a compound’s polarity and its solubility in water.
Background:
“Oil and water don’t mix!” You’ve probably heard this phrase before. Though this phrase is
true, there are plenty of substances that do dissolve in water. The polar nature of the water molecule
is largely responsible for its remarkable solvent action. Because of its polarity, water is able to
dissolve ionic compounds, such as sodium chloride and copper sulfate, and polar covalent
compounds, such as sugar and ammonia. Many chemical reactions and most biochemical reactions
take place in water.
Similarly, many substances dissolve in oily, nonpolar solvents, such as gasoline and
kerosene. In general, only nonpolar molecules will dissolve in nonpolar solvents.
Materials:
safety goggles
1 spatula
1 dropper pipette
10 small test tubes
1 test-tube rack
1 plastic wash bottle
sodium chloride, NaCl
sucrose, C12H22O11
sodium thiosulfate, Na2S2O3
calcium carbonate, CaCO3
potassium sulfate, K2SO4
ethanol, C2H5OH
hexane, C6H14
kerosene, C12-C15
glycerin, C3H8O3
Procedure:
A. Record the chemical formula, physical state, and color of each of the substances in the Materials
section, with the exception of distilled water.
B. Test each of the substances for water solubility. Add 3-4 mL of distilled water to each small test
tube. Add a very small quantity of the substance to be tested to an individual test tube. For
solids, use a sample about the size of a match head. For liquids, use one drop. Be careful not to
contaminate the chemicals with one another.
C. Flick the test tube gently and note what happens. If all of the substance dissolves, add another
small quantity and flick gently. Repeat the process several more times if the material continues
to dissolve. Describe each substance as insoluble, slightly soluble, or very soluble, based on its
behavior. Record these descriptions in Data Table 1.
D. Dispose of the hexane and kerosene samples as directed by your teacher. Dispose of all other
samples by flushing them, with water, down the drain. Rinse the test tubes.