COMPLEXOMETRIC DETERMINATION OF WATER HARDNESS LAB

At five minute intervals over the next fifteen minute period, record the color intensity of the solution of each test tube.

We know that that the end point of the titration is reached when, after drop after careful drop of NaOH, the solution in the flask retains its pale pink color while swirling for about 30

Next, I poured distilled water just below the 250ml mark on the neck of the volumetric flask.

7. Click in the Stockroom. Double-click on the bottles of NH3 and H2SO4 to move them from the shelf to the counter and return to the laboratory. Drag the bottle of NH3 to one of the three spotlights on the

XII. Take the 250 ml beaker to your lab bench. Set up a gravity filtration with a plastic funnel, folded wet filter paper, and an Erlenmeyer flask. Pour the content in the 250 ml beaker slowly through the filter paper. Wash the filter paper with deionized water. Dispose of the filtrate in the proper labeled waste container.

The observations were recorded and the lab was concluded by cleaning the fume

For Standard solution 1, we added 2 mL stock solution with 8 mL DI water

After that, 0.1 ml of solution in Tube 4 was poured into plate 1A, the solution was spread over the surface evenly. These steps were repeated using 1ml from Tube 5 - plate 1B, 0.1 ml from Tube 5- plate 2A, 1 ml from tube 6 - plate 2B, 0.1ml from tube 6 - plate 3A, from tube 7 - plate 3B.

After that, both spouts were closed and the burets were filled with the solution being used to around the zero mark. Some solution had to flow out in order for there to be no air bubbles at the tip of the burets. The burets were then labeled acid or base to fit their corresponding solutions. To start the titration, the initial values of the burets were recorded in the data table. A known volume, 10 mL, of HCl was delivered to the Erlenmeyer flask, and a few drops of the indicator, phenolphthalein, were added also. In the first trial, 3 drops of this was used. Then, the spout of the buret containing the NaOH solution was opened, and the chemical was added to the flask. While the NaOH was mixing with the other solutions, the flask was constantly being swirled. As the color changed briefly and returned to normal, the flow of the NaOH was slowed down. By adjusting the spout of the buret, the flow was drop by drop. If the color became too bright pink, single drops of HCl were supplied to the solution to get it to a faint pink color. The endpoint was determined by swirling the flask for at least a minute, and seeing if the color stayed while viewing it on top of a white piece of paper so the color was more

As in the Chemistry 101 Lab Manual, pages 75 to 77. No changes to the procedure were made. Data and results Table 1: reagents used. Reagent MW

4. The flask was swirled for 10-15 seconds and checked if the solid dissolved. If not another portion of the solvent was added. 5.

Wear eye to prevent contact eyes. Always wipe any spillages of chemicals to avoid any skin contact. Use the nearest eye-wash in the lab until you can see clearly, and the paining sensation subsides. Wash the mouth out with water if the chemical enters the mouth, do not induce vomiting. Drink water in short bursts to cool down the throat and keep the airway open.

Once obtained, remove 90 mL of the saturated calcium hydroxide and add it to another 125-mL flask. Make sure the solid calcium hydroxide within the solution is remained untouched. • Acquire a 150-mL beaker in order to obtain 90-mL of calcium hydroxide solution present above the solid Ca(OH)2 for analysis purposes. • Obtain a pipet and since it with 25- mL of saturated calcium hydroxide

Get a spinach leaf to obtain pigments from. Set the chromatography paper on top of

Prepare 0.05% of Tween-60, 200 ml per flask the 12th day of incubation. On the 13th day observe each flask for any abnormal growth and contaminants. Pore aseptically 200 ml of sterile 0.05% Tween-60 solution in each flask. Shake each flask