CHMY 171 Lab A
Part 1: Melting point: Cinnimic acid and Urea
Goal: To draw conclusions about the melting points for pure substances versus mixtures.
Procedure:
Step 1: Research the known melting points of Cinnimic acid and Urea.
Step 2: Determine the melting points of Cinnimic acid and Urea by experiment.
Step 3: Make a mixture of 50% Cinnimic acid and 50% Urea and find the melting point.
Be sure to mix the solids thoroughly.
What did you learn about the melting point of a pure substance compared to the mixture?
There are two important differences – what are they?
Part 2: Density: Copper and water
Goal: To experimentally determine the density of a solid and of a liquid.
Procedure:
Step 1: Research the known densities of copper and water. Be sure to note the
temperature.
Step 2: Determine the densities of copper and water by experiment. Always record data
with the correct number of significant figures. Try to perfect your technique until you
match the known values. Create a list of experimental factors that you were able to
improve to get a better correlation between your experimental value and the reference
value.
Why is the temperature important when measuring the density?
How many significant figures does the experimental density have?
Part 3: Distillation: Water and Methanol
Goal: To learn proper distillation technique. To write a comparison of simple distillation
and fractional distillation based on the results.
Procedure:
Step 1: Research the boiling points of water and methanol.
Step 2: Use simple distillation to experimentally determine the boiling points of water
and methanol. Half the class will do water and half will do methanol. You will share
your results with the class.
Step 3: Make a 50:50 mixture of water and methanol and attempt separation by
fractional distillation. Collect two portions of distillate as well as what remains in the
flask (they should each be roughly one-third of the original mixture.). Record the
beginning and final temperature of each fraction collected.
Step 4: Compare the boiling point and density of each of the three samples.
Did you achieve separation?