Now to begin, pour 50 mL of the sodium phosphate buffer solution with a pH of 6.84 into the 150 mL beaker. From here on out, the sodium phosphate buffer solution will be referred to as simply the buffer solution. Next, locate the indicator called bromothymol blue (0.04%) and add 20 drops to your 150 mL beaker. The solution should then appear green. Next, obtain a 5 mL serological pipet and thoroughly rinse it with the buffer solution, then discard the buffer solution into the 250 mL beaker.
Procedure Step 1, Obtain acid, in a 100 ml Erlenmeyer flask add 35 ml of .2M HCl solution. Step 2, add an indicator to the acid, select the flask and add 2 drops of phenolphthalein indicator. Step 3, Fill buret with NaOH, obtain a 50 ml buret and fill with .2M NaOH solution.Step 4, Titrate NaOH into HCl until end point, record initial buret volume and add NaOH (quickly at first then slowly) until the HCl solution turns pink and record the final buret volume of NaOH in buret. Step 5, repeat steps 1-4 using pH meters, add a pH meter to the acid solution. Record several points of pH and NaOH added (especially near equivalence point) to be use later to prepare a titration curve.
William Flores-Paz Monitoring Acid-Base Titrations with a pH meter October 30, 2013 Introduction The purpose of this experiment was to record the volume of HCl and acetic acid with a NaOH with a known molarity. This data would allow us to create a graph so we could compare the two titration curves. We would then use these curves to calculate the unknown molarities. HCl + NaOH >H2O + NaCl This equation shows the relationship between the acid and the base then the reaction goes forward and they are titrated creating salt and water. This particular reaction is a strong acid and a strong base which means that when the reaction reaches the equivalence point, the moles of the acid and the base are equal and the solution is neutral so the pH should be around 7.0 depending on the final volume of each solution.
Add 0.1M HCl one drop at a time. Use the stirring stick and stir each time a drop has been added. Determine the pH after 5 drops have been added. Repeat the procedure until 30 drops have been added. 4.
Approximately 20 drops of a .04% Bromothymol blue solution was then added to the beaker of the phosphate buffer. Using a clean 5 mL serological pipette, transfer 5 mL of the phosphate buffer and Bromothymol blue solution to each of three clean 150 mL beakers. Next, using the buret for HCl, add 1 mL of HCl to one of the three beakers, then label this beaker “Yellow”. Next use the buret for NaOH and add 1 mL of NaOH to another of the three beakers, and label this beaker “Blue”. Lastly add 1 mL of water using the buret for water to the last beaker, and label this beaker “Green”.
10 mL of each solution [0.16M KI, 0.0055M (NH4)S2O8, 0.12M Na2S2O3, and water] were added to an Erlenmeyer flask along with about 0.2 g of starch and a drop of EDTA (to prevent coagulation) and mixed with a stir bar. The reaction was conducted twice for room temperature (24.5ºC), cold (1.5ºC), and warm (37.0ºC). Observations were made as the mixture changed from clear to a dark blue, almost black. The time for this color shift was recorded (in seconds). By varying the temperatures, variables A and Ea could be determined.
The equivalence point of titration occurred at a volume of 31 mL 0.081M NaOH (aq). The halfway volume of titration was thus 15.5 mL and the pH of the titration system at this point, as determined graphically, was 5.08. After identification of half point, Henderson–Hasselbalch equation pH=pKa, was used to determine the value of Ka. The resulting Ka value and the concentration of KHP made it possible to calculate the initial pH of the acid, which were 3.19. How it was expected the pH at equivalence point was 9.17 this is because of the domination of hydroxide ion in solution.
Lesson written by Carolina Sylvestri Experiment: Reaction Between Ions in Aqueous Solutions The Monster Mash Background: Ionic solids dissolve in water to form aqueous solutions which conduct electricity. These solutions contain both positive and negative ions in such numbers that their net electric charge is zero. In this experiment, you will mix various ionic solutions, two at a time, to determine which combinations form precipitates. Knowing which ions are present makes it possible to deduce which of the possible ion combinations are responsible for the precipitates. From your data table, it will then be possible to generate a solubility table.
Unknown Final report 1. Introduction: The purpose of this lab was to identify two unknown bacteria cultures using various differential tests. The identification of these unknown cultures was accomplished by separating and differentiating possible bacteria based on specific biochemical characteristics. Whether the tests performed identified specific enzymatic reactions or metabolic pathways, each was used in a way to help recognize those specifics and identify the unknown cultures. The differential tests used to identify the unknown cultures were oxidase, catalase, lactose and sucrose fermentation, nitrate reduction, gelatin hydrolysis, starch hydrolysis, manitol salt, MR-VP, citrate, indole, urease, DNase, and coagulase.
A cuvette block, four cuvettes, three 50 mL beakers, one 150 mL beaker, and one 5mL pipet were obtained. The phosphate buffers NaH₂PO₄ and Na₂HPO₄ were procured weighing .4060g and .4106g respectively. The phosphate buffers were then transported to the 150mL beaker. Next 50mL of distilled water was measured using a graduated cylinder and added to the 150mL beaker. Twenty drops of bromothymol blue was also added to the 150mL beaker.