Using Buffers. Jason Blot. 02/26/2017. . Purpose:. . The

Buffers can be used to resist change in pH in an acid or base solution. The purpose of the lab is to understand the properties of buffers in relative concentrations, in the presence of a strong acid/base and dilution of buffer components the ammonia/ammonium buffer system. In this case, these laboratory techniques associated with buffers are performed to determine the pH values in diluted solutions. This is done by observing the Henderson-Hasselbalch equation. This represents the pH value by comparing the p value and the concentrations of a weak acid and conjugate base of a buffer solution, as long as assumptions are valid. From there, a pH vs log can be used from the values obtained. Then, the theoretical pH of solutions can be determined with the addition of a strong acid (HCl) and base (NaOH). From this, the effect of dilution can be viewed when plotting the calculated pH values vs dilution on the same graph.

The first step that needed to be done in this experiment was adding hydrochloric acid (HCl)

In 2 and 7 I added 50 mL of .1 M NaCl. I added sodium acetate to the rest of the beakers: 1 gram to 3 and 8, 5 grams to 4 and 9, and 10 grams to 5 and 10. I then filled the beakers that contained the solid sodium acetate with 50 ml of .10 M acetic acid. Specifics can be found on page 84 of the lab manual. Though the lab manual instructed to use a pipet, we did not have an accurate 1 mL pipet or a graduated pipet, so we instead prepared two graduated burets with 1 M Sodium Hydroxide and 1 M hydrochloric acid. Using a standardized pH probe with a Lab Pro to measure changes in pH, we added 1 mL of HCl at a time and recorded the changes. The same was done for the NaOH.

twice. Place the pH probe in the beaker and record the pH in the data table. Drag the beaker to the red

3. We poured tube 1 with the solution in tube 3 to combine them. We repeated this for all of the tubes. Each of the tubes in step 1 was mixed with a tube in step 3, making there be 6 total test tubes with a solution in it.

1. Describe the graph of pH values over the course of the reaction in Part II. Was the change in pH consistent over the course of the reaction? Do your best to explain the reason for the shape of the pH curve in your own words:

Again, label 7 1.5ml tubes 0 thru 6. Place 15μl of each serially diluted extract into its corresponding labeled tube. Next add 465μl of media into each tube. Then 60μl of Alamar blue in each tube. Finally add an additional 60μl of cells (adjusted to 10,000 cells/20 μl). Vortex each tube for 5 seconds. Now, take 3 different samples 190μl samples of concentration 0 and put it in Wells A2, B2, and C2. Repeat this step again by taking 3 more different 190μl samples of concentration 1 and putting it in wells A3, B3, C3. It should be noted that it is important to vortex each 1.5μl tube again be-fore putting it into the 96 well plate. Contin-ue this same procedure consecutively for the re-maining concentrations.

Table 1: This table shows the position that the solution was at inside the graduated tube it was held in at each time interval it was measured.

1.) Measure out 20ml out of the water and place it into a glass beaker

3. Add a drop of enzyme solution to only one of the wells. The other well without enzyme added to it will be your control.

Gather the following lab equipment: Goggles, test tubes, 24 well plate, Gas assembly with copper and plastic tubing and a #00 stopper, short stem pipet, rubber stopper #00 with one hole and a pipet tip with plastic gas delivery tube, 2 small tables of AlkaSeltzer, 4mL Bromothymol blue .04%, 20 mL hydrochloric acid, 4-6 pieces of manganese metal, 4-6 pieces of mossy zinc, and 3 pipet bulbs.

Next, select the test tubes and put it on the test tube rack; and, wash all the glassware with distilled water. Then, use the 250 mL beaker to prepare a hot water bath and regulate it to 200 C. Moreover, prepare the scenario to analyze the solution for the presence of Pb2+, Hg22+, and Ag+ ions. Start by labelling the test tubes from 1-8. Then, use the tube 1 and add 10 drops of 10 cation solutions (note: the unknown solution must be in the tube 8). Next, add 8 drops of 6 M HCl and mix it, using a stirring rod.

The method I used in the experiment was followed by the lab manual of “Fundamentals of Life Science by Brenda Leady” (Leady 2017). We conducted an experiment of 8 different tests, 4 of the different classifications of pH, and 4 different

d. Add one drop of I2KI solution to each of the wells and record your result in the table below. Table 2. Iodine Test Results

2. Following solutions are added to the tubes and the pH of each tube is determined: