This lab was divided into four parts: Part 1 was about testing for hydrogen gas.
Part 2 involved finding the pH levels of certain elements.
Part 3 was about testing for solubility.
Part 4 was simply taking in the observations and making them make sense.
Part 1: 1) Pour about 2.5 mL of distilled water into a clean, dry test tube and stand the tube in the test tube rack. Add a calcium turning to the water in the tube. To collect gas being released, invert a clean, dry test tube holder.
2) Test for hydrogen gas by inserting a burning wood splint into the upper part of the inverted tube.
3) Add a few drops of phenolphthalein solution to the reactant tube. After making your observations, discard the contents of the tube and clean and dry the tube.
4) Repeat step 1, using a 10-cm piece of magnesium ribbon in place of the calcium. If no visible reaction occurs, heat the water to boiling, using a test tube holder to hold the tube over the burner flame. CAUTION: Point the tube away from yourself and others while heating.
5) Once the water is boiling, stand the tube in a test tube rack and, using a test tube holder, invert a collecting tube over the reactant tube. After a few seconds, test for hydrogen gas.
6) Turn off the burner and add a few drops of phenolphthalein to the reactant tube. Record your observations. Discard the contents of the tube, and clean and dry the tube.
7) Obtain 2.5-mL samples of saturated solutions of calcium hydroxide, magnesium hydroxide, and barium hydroxide. Test each solution with pH paper. Record the pH of each solution.
8) Using the laboratory balance, measure out 1-g sample of magnesium sulfate. Place it in a clean, dry test tube.
9) Repeat step 8 for calcium sulfate and barium sulfate.
10) Add 2.5 mL of distilled water to each tube. Using a glass stirring rod, stir each mixture thoroughly, getting as much of each solid to dissolve as possible. Record your observations of the relative solubilities of each of these compounds.
11)Stand 3 clean, dry test tubes in the test tube rack. Using the 0.1M solutions, add about 2.5mL of the MgCl2 solution to one tube, 2.5 mL of the CaCl2 solution to a second tube, and 2.5 mL of BaCl2 to the third tube.
12)To each of the solutions in the test tubes, add about 1 mL of the Na2CO3 solution. Record your observations.
burner pH paper
test tubes, 13 x 100 mm (3)stirrer
test tube holderflame tester
test tube rackfilter paper
calcium turnings (Ca)saturated solutions of :
magnesium ribbon (Mg)calcium hydroxide
magnesium sulfate crystals (MgSO4)magnesium hydroxide
calcium sulfate crystals (CaSO4)barium hydroxide
barium sulfate crystals (BaSO4)0.1 M solutions of :
distilled watersodium carbonate
phenolphthalein solutionmagnesium chloride
“See attached ditto”
For us, there were not a whole lot of expectations for this lab except for testing for the hydrogen gas, where we did believe that gas would be generated in both the calcium and the magnesium, and in both cases, our hypothesis was correct. This lab had a lot of possible sources of error simply because if anyone had reused or put back the sample of an element, the entire quantity of that element was contaminated. So, there could be contaminated samples, dirty test tubes, and even possibly dirty water.
I had thought that this was going to be a confusing lab, but as it went on, I found myself understanding the material quite well. We were both quite intrigued by the hydrogen gas experiment with the generation of sound from fire and gas. All in all, I found this to be a pretty fun lab.