Pre Lab Questions: 3pts
1.What are the learning goals of this lab?
The learning goal of this experiment is to view and experience the melting point and boiling point of different substances. 2.Why is acetamide not allowed in contact with your skin? What precautions does one have to take to work with this chemical? Acetamide is a carcinogen, which can cause cancer. Therefore, it should not be allowed to come in contact with a person’s skin. Any person working with this chemical to wear gloves, and follow all precautionary procedures. A person should also make sure to wear long sleeves, closed toed shoes, and long pants to avoid contact with the skin. 3.Define the B.Pt of liquids and M.Pt of solids. Why is it important to determine these physical properties of a substance?
The melting point of a solid is the point at which a solid becomes a liquid with standard atmospheric pressure. The boiling point of a liquid is the temperature at which the vapor pressure of a liquid equals the external pressure. It is important to know these characteristics of a substance so that you can handle them in the correct manner. The boiling point and melting point can also be used to identify an unknown substance.
Liquids and Solids
(Write the procedure in your own words after you read the manual) 1.B.Pt:
•At the beginning of the experiemtn make sure you gather all necessary materials, i.e., spoon, alcohol, rubber bands, and a sheet of paper. When doing an experiement, be sure to set up a data table to record all results. In this case a data section has been provided by the instructor. Then, you should complete the assembly, exactly like the illustration provided by the lab manual. •Put 1 mL of alcohol in the test tube. Then you should take the thermometer and place it side by side with the test tube. Make sure that the bulb of the thermometer is even with the bottom of the test tube. Then use a rubber band to attach them together. Then insert an inverted closed end capillary tube into the test tube.
•Then make a water bath assembly exactly like the illustration provided in the lab manual. Then take a 100 mL beaker and fill it half way with warm tap water. •Then you should take the entire test tube assembly and put it into the water bath, so that the alcohol surface level is below the water in the beaker surface level. Then set up your burner stand, and place the beaker on top of it. •Light the burner fuel and put it beneath the stand. Carefully stir, to make sure everything heats evenly. Watch and wait for there to be a continuous boil and streams of bubbles coming from the water bath. •Now, you want to put out the fire by putting the cap on the burner fuel slowly and carefully. This will eliminate the oxygen to the fire. Then observe the boiling liquid from the capillary tube. Once you notice the stream slowing down, measure the temperature as you see the last bubble from the liquid. Record result in data table provided. •Now, you should repeat all previous steps two more times, and record results. The published boiling point of alcohol is 82.4 degrees Celsius. Calculate the error between your results and the published boiling point.
•Make sure you have on gloves before moving on to this step. Insert the powdered acetamide into the open end of the 2nd capillary tube. You can do this by slowly and carefully pushing the tube into the powder acetamide. •Now, make sure you get all the acetamide at the bottom of the tube by gently tapping the capillary tube. You want it to occupy at least 1-2mm at the closed end of the capillary tube. Then you should take the thermometer and place it side by side with the test tube. Make sure that the bulb of the thermometer is even with the bottom of the test tube. Then use a rubber band to attach them together. •Then make a water...