Laboratory Experiment On Chemical Reactions: Macroscopic Observation

The aim of this experiment is to determine the water percentage and practice qualitative and quantitative observations. For the first part we heated an anhydrate salt to see the change in mass and water percentage, for the second part we heated our sample to observe the physical changes such as change in color. For the last part we mixed chemicals to observe physical changes such as change in color, odor, and temperature. To achieve the aim we heated our samples with bunsen burner. We expected to obtain a decreasing mass in part 1 and a change of appereance in part 2 and 3.

Experimental method

For the first part of experiment 1, we used crucible, laboratory balance, spatula, bunsen burner, clay triangle, gauze mat, ring clamp holder, crucible tongs, laboratory stand, three prong clamp, and an unknown anhydrous salt. We prepared the set-up and weigh a dry crucible with and without it’s lid. Than we put 2 grams of unknown solid and weigh the entire assembly. We than turned on the bunsen burner and started heating the anhydrous salt inside of the curicible. We increased the heat after a minute and turned of the bunsen burner 20 minutes after we increased the heat. We let it cool down for 15 minutes and weigh the entire assembly. 20 mintues after we turned off the bunsen burner we turned it on again and started heating. After 10 minutes we turned off the heat, let it cool down, and weigh again.

For the second part, we used test tubes, spatula, distilled water, bunsen burner, and CuSO4∙5H2O. We started examining the solid and wrote our observations. Than we started heating until it changed color. Because of the heat our test tube broke down and we started heating with a new tube. After we obtained the change of color, we added distilled water and obtained the new changes.

For the third and last part, we used test tubes, spatula, test tube rack, and several solid and liquid chemicals. We took 6 test tubes and put two chemicals each until they react with eachother. We put Pb(NO3)2 and K2Cr2O7 in tube A, NaHCO3 and HCl in tube B, NH4Cl and H2O in tube C, NaCH3COO and H2O in tube D, Fe(NO3)3 and NH4SCN in tube E, and NaCl and AgNO3 in tube F. We recorded our observations.

Results

Part I: First we weigh the cubicle with and without the cap. Without: 34. 366 grams but it was wrong so we changed it to 34. 365 gramsWith: 58. 102 grams but it was wrong so we changed it to 58. 100 gramsAfter we add the solid, entire assembly was 60. 101 gramsGiven molar mass: 322. 19 g/molWe started heating gently at (14:08) and increased the heat at (14:09). We turned off the bunsen burner at (14:29). Bottom of the crucible was supposed to turn red but it did not. Cooled down weight was 58. 938 grams.

Error: we spilled some of the solid while we were trying to put it back on the bunsen burner. We started heating again at (14:49) and started cooling again at (15:02). At (15:13) we weigh the assembly again and it was 58. 895 grams. Error: we spilled more while we were trying to put it on the laboratory balance.

Part II: We started by examining the chemical. It was a vibrant bright blue solid with sand-size particles. We started heating at (14:32). At (14:35) the bottom of the test tube broke down. At (14:36) we started again with a new test tube.

Obtained liquid was clear and color of sample after heating was pale blue on the inside and White on the outside. We added distilled water at (14:54). After adding the distilled water, color of sample changed back into bright blue.

Part III: The amount of chemical we added to each tube was random. We kept adding until they reacted.

Conclusions

In part one, we observe that after heating the anhydrate salt lost 1. 206 grams. It was more than we expected but that is because we dropped the crucible twice and spilled some. In part two we observed that the changes in the sample was caused by dehydration. We saw that it turned into a one piece solid and changed colors. When we added distilled water, it turned back to how it was in the beggining. Which is what we were expecting in the beggining. In part three, as we were expecting we observed physical changes. Solids soluted in liquids and when two liquid reacted they changed colors.