This preview shows page 1. Sign up to view the full content.
Unformatted text preview: he test tube, you need not include the solid in the
quantity you pour out. Place the probes into the water solution on the watch glass, and give the
probe a few seconds to equilibrate. Once equilibration seems to have been reached, record the
conductivity for that solution. Discard the solutions according to the instructions given in lab,
and remember to clean the probes and watch glass and rinse them all off with distilled water very
well. Repeat for each water solution.
Dakota State University Page 55 of 232 Experiment 2: Compound Types General Chemistry I and II Lab Manual Melting Points:
Here we are not interested in absolute melting point temperatures, but rather, relative
melting points. Place a VERY SMALL AMOUNT of each solid (just enough to see it) onto a
scoopula, close enough that they can be viewed and heated more or less at the same time, but far
enough apart that you can easily remember which is which. Light a Bunsen burner, and, being
very careful not to burn yourself, pass the scoopula through the flame several times. Note the
order of melting (which melts first, second, etc) and whether or not any appear to burn rather
than melt. Record your observations. Remember that the compounds that melt first have the
lower melting points. You might not be able to get all of the compounds to melt; these are all
very high melting point compounds.
Based on the results from the procedure, categorize each compound as non-polar covalent, polar
covalent, or ionic. Dakota State University Page 56 of 232 Experiment 2: Compound Types General Chemistry I and II Lab Manual Data and Observations:
Compound Number General Observations Solubility:
In the following table, record whether each substance is soluble, partially soluble or insoluble in
each of the solvents.
Compound Number Polar Solvent Non-Polar Solvent Observations: Conductivity:
Compound Number Conductivity Observations: Dakota State University Page 57 of 232 Experiment 2: Compound Types General Chemistry I and II Lab Manual Melting Point:
In the following table, record which melted first, second, third, etc. in “order of melting”
Compound Number Order of Melting Observations Observations: Classification:
In the following, record for each compound if you believe it to be non-polar covalent, polarcovalent or ionic.
Compound Number Dakota State University Compound Type Page 58 of 232 Experiment 2: Compound Types General Chemistry I and II Lab Manual Pre-Lab Questions:
1. Describe briefly how we are determining the order of melting. 2. What test are we using to determine if a compound is an electrolyte or a non-electrolyte? 3.
If you have a compound that is not soluble in hexane or water, and is an electrolyte, what
kind of compound do you expect you will have? Dakota State University Page 59 of 232 Experiment 2: Compound Types General Chemistry I and II Lab Manual Post-Lab Questions:
1. Is it possible to have an ionic compound that is not water soluble? 2. Is it possible for an electrol...
View Full Document