Introduction/Theoretical Background: A common task in chemistry is the determination of a substance present in a product. If the product contains a substance that can be oxidized, then it is possible to determine the number of moles of that substance by titrating the sample with a solution of a strong oxidizing agent. In this lab, a solution of KMnO4, an oxidizing agent, will be standardized by titration with a solution containing a known concentration of iron (II) ions, (Fe+). The concentration of oxalic acid solution will be determined by titration with the MnO4- solution that had been standardized first. The purpose of this lab is to standardize a solution of potassium permanganate by redox titration with a standard solution of …show more content…
Add 20 mL of distilled water to each flask and swirl.
5. Warm the first flask to about 85°C on the hot plate.
6. Immediately titrate this solution with the standardized MnO4 solution from Part 1. Record both the initial and final buret readings in the Part 2 Data Table.
7. Repeat steps 5 and 6 with the second flask.
Data Table:
| Trial 1 | Trial 2 | Trial 3 | Volume of Fe2+ solution titrated | 10 mL | 10 mL | 10 mL | Initial volume of MnO4- solution | 3.5 mL | 14.5 mL | 24.8 mL | Final volume of MnO4- solution | 14.5 mL | 24.8 mL | 35.32 mL | Volume of MnO4- added | 11 mL | 10.3 mL | 10.52 mL |
| Trial 1 | Trial 2 | Volume of H2C2O4 solution titrated | 25 mL | 25 mL | Initial volume of MnO4- solution | 2 mL | 15 mL | Final volume of MnO4- solution | 15 mL | 28 mL | Volume of MnO4- added | 13 mL | 13 mL |
Calculations:
Balancing:
Reduction: 8H+ + MnO4- + 5e- -> Mn2+ + 4H2O
Oxidation : Fe2+ -> Fe3+ + e-
8H+ + MnO4- + 5e- -> Mn2+ + 4H2O
5Fe2+ -> 5Fe3+ + 5e-
Balanced overall: 8H+(aq) +MnO4-(aq) + 5Fe2+(aq) -> 5Fe3+(aq) + Mn2+(aq) + 4H2O(l)
Normality:
Number of electrons transferred = number of equivalents = 5
Equivalent weight: (39.10g/mol + 54.94g/mol + 4*16.00g/mol)/5 = 31.61g/mol Normality = 5M = 5 * .020M = .100N
Volumes: Trial 1:
FeSO4: 24.60mL - 14.76mL = 9.84mL
KMnO4: 26.20mL - 9.18mL = 17.02mL
Trial 2:
FeSO4: 34.59mL -
with a solid oxidant that is composed of KMnO4 and CuSO4. 1.0mL of diphenylmethanol was placed into
1. We measured 2 mL of diluted hydrogen peroxide (the substrate), 1 mL of guaiacol (the product indicator), and 1 mL of neutral buffer (pH 7) with a syringe and disposed it into tubes 1, 2 , 4, 9, 11, and 12.
The lab leaders and the Punk Rock Warlord prepared three different concentrations of catechol oxidase by extracting potato juice (because it contains lots of catechol oxidase). Pure catechol, a 5mL test tube, 1mL/5mL
For the concentration experiment three different concentrations were made of the KMnO4. Three test tubes were filled with 4 ml of water. The first test tube had 1 ml of the 500 KmnO4 added to it. Then the second test tube had 1 ml from test tube one and 4 mL of water. For test tube 3, 1ml was taken from test tube two. Each concentration was placed into a dialysis tubing using the strings to tie off one end and the clamp to close off the other end. Before the dialysis tubing was placed in the beaker, 1ml of a sample was placed in a cuvette to blank the spectrophometer. Each stir plate was set on a low speed and the dialysis was hung in the water by a string. Every 5 minutes that passed a sample of 1 ml was taken and put into a cuvette. The cuvettes were placed in the spectrophometer to measure the absorbance of each solution. The measuremnts were then recorded in lab notebook. Once the measurements were documented, the average of absorbance and concentration was recorded.
1. Gathered all required materials to designated lab bench. 2. Considered all safety precautions including the prevention of spilling water to avoid falls, handling glassware carefully to prevent shattering, avoiding long periods of working with warm water to avoid burns and avoiding the digestion/inhalation of by-products produced after the reaction (e.g. ethanol and carbon dioxide gas). 3.
Please complete the entire experiment as instructed in the lab manual except for any modifications noted below. Fill out the
23. Measure the pH with a pH strip and record the data of the new solution in Table 3.
4.Measure 35mL of warm water and add them into each of the 4 test tubes at about roughly the same time. It is essential that the water is warm. Do not seal the test tube.
The pipette was used to transfer 8 mL of the 0.5 molarity solution into the graduated cylinder. Distilled water was added to raise the bottom of the meniscus to the 20.0 mL line and the solution was transferred into the beaker after it was rinsed with the solution. The pipette was used to take a small quantity of the solution and rinse and then fill a test tube with the solution. The amount of 0.2 molarity solution needed to create 20.0 mL of 0.1 molarity solution was calculated as 10.0 mL. The pipette was used to transfer 10.0 mL of 0.2 molarity solution into the graduated cylinder and distilled water added until the bottom of the meniscus reached the 20.0 mL line. The solution was transferred to the rinsed beaker and then a portion placed into a test tube that had been rinsed with the solution. The amount of 0.1 molarity solution required to create 20.0 mL of 0.05 molarity solution was calculated to be 10.0 mL. The pipette was used to transfer 10.0 mL of 0.2 molarity solution into the graduated cylinder and distilled water added until the bottom of the meniscus reached the 20.0 mL line. The solution was then placed into a beaker that had been rinsed with the solution and then into a rinsed test
The potentiostat was set up by the instructor with acetate buffer. The sample was deaerated with nitrogen gas for 5 to 8 minutes in order to remove oxygen. Oxidation and
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The purpose of this experiment was to determine how much KMnO4 was needed to titrate approximately 1 mL of an Unknow X101 concentrated solution of Oxalic Acid. A standardized KMnO4 solution was used on a known solution of Oxalic acid to help determine the unknown percent oxalic acid in unknown X101. The unknown sample for this experiment was sample x101 which theoretically was a % Oxalic Acid dehydrate sample but, the average of all three trials determined it to be a 6.7% percent Oxalic acid.
An acid-base titration is the determination of the concentration of an acid or base by exactly neutralizing the acid/base with an acid or base of known concentration. This allows for quantitative analysis of the concentration of an unknown acid