Work to be done: By experiments find out how chemical equilibria works. Chemicals and apparatus: Two beakers Five test-tubes Kaliumtiocyanat, KSCN 0. 002 M Kaliumtiocyanatsolution, KSCN + H 2 O Dinatriumfosfat, Na 2 HPO 4 0. 002 M Iron (III) nitratesolution, FeNO 3 0. 2 M Silvernitratesolution, AgNO 3 Lab: Lab 1 One test-tubes is filled half of distilled water (A) and another with kaliumtiocyanatsolution (B).
Both solutions are colorless. Solution (B) contains SCN-. I add five drops of iron (III) nitratesolution to both test-tubes and the kaliumtiocyanatsolution turns dark-red. The explanation is that there has been a reaction in solution (B), Fe 3+ + SCN- FeSCN 2+, where FeSCN 2+ has a dark-red color. Lab 2 The solution in test-tube (B) is placed in five other test-tubes. I will now perform four different experiment and then compare with the original solution, and therefor I label the test-tubes a, b, c, d and e.
In test-tube (a) I add some KSCN (crystals) and therefor raise the concentration of SCN- in the solution. The visible change is that the solution turn darker red. And since FeSCN 2+ is red, the conclusion is that the solution contains more FeSCN 2+. To test-tube (c) I add some FeNO 3 and the concentration of Fe 3+ is increased and the solution turns darker red the concentration of FeSCN 2+ is higher.
Since no more SCN- has been added the ratio Fe 3+ and SCN- must be in equilibrium. The solution now contains Fe 3+, SCN-, FeSCN 2+, NO 3- and K+. To test-tube (d) I add five drops of silver nitrate, AgNO 3, and the solution is turning brighter – the concentration of FeSCN 2+ must decrease. There seems to be a fight about the SCN-ions, both Ag+ and Fe 3+ want them, but the Ag+ions seems to win and form a salt, Ag SCN, that is hard diluted in water. The effect is, as described earlier, that the concentration of FeSCN- has decreased and the color of the solution is lighter red. The reaction formula is Fe 3+ + SCN- FeSCN 2+, the reaction i to the left and the reaction is reversible.
The Essay on Beet Lab Test Tube
MATERIAL AND METHODS Stability of cell membrane using pHF or the lab experiment for testing the stability of beet cell membranes using pH, many materials were used as follows. Obtaining a beet we punch out cores, using a cork borer. After washing the cores we put each one inside a separate test tube, and added a different pH solution in each one. After 3 minutes in these exposure solutions, we ...
In the last test-tube I add some dinatriumhydrofosphate, Na 2 HPO 4, and the solution becomes colorless, there is no more FeSCN 2+. The concentration of Fe 3+ has decreased. In the reaction Fe 3+ + SCN- FeSCN 2+, the reaction is to the left. CONCLUSION: In the reactions above I have changed the equilibrium by changing the concentration of different substances.
