Chemical Background
A redox reaction is a chemical reaction that only happens when oxidation and reduction process take place simultaneously. A redox reaction helps determine the concentration of a solution containing oxidizing or reducing agents. The concentration of potassium permanganate solution, KMnO4 was not given in the experiment that was carried out. By conducting a redox titration, the concentration of potassium permanganate solution, KMnO4 can be determined.
Discussion Before performing the titration, the burette was rinsed three times with distilled water and rinsed once with potassium permanganate solution. The volumetric pipette was also rinsed three times with distilled water and after that rinsed once with iron
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There was an increase in temperature after the concentrated sulphuric acid was added into the volumetric flask containing the iron (II) solution, the outer glass of the volumetric flask was warm. The reason why concentrated sulphuric acid was added is so that the iron (II) solution is stabilized. This is because Iron (II) is vulnerable to be oxidized but the oxidation of iron (II), 〖Fe〗^(2+) to iron (III), 〖Fe〗^(3+) is unable to take place in the presence of an acid. Sulphuric acid which is a strong acid will react with potassium permanganate solution, which is an oxidizing agent, to produce high concentration of hydrogen ions in order to convert oxygen from the potassium permanganate solution into water molecules. Therefore, diluted sulphuric acid was added to the standard iron (II) solution before titration took place. The color of the iron (II) solution changes from pale yellow to pale pink when titration was taking place. The true value of the concentration of potassium permanganate solution is 0.0186 mol/L but the concentration obtained through titration was 0.0176 mol/L. This shows that the results found in the experiment is inaccurate. However, the precision of the results is high as the concordant values were obtained at the first 3 trials of the …show more content…
The eye level may have not been perpendicular to the meniscus of the liquid when recording a measurement and this may have caused inconsistent readings when repeating the redox titration. Several steps can be taken to improve this error. A ruler should be used to align the eye level of the reader and the meniscus of the liquid. Due to the dark intensity of color of the permanganate solution, a paper should be placed on the outer glass of the burette by placing the tip of the paper at the meniscus when recording the initial value and final value of the permanganate solution. Another random error that occurred is the false detection of the end point when titrating the permanganate solution into the conical flask. The tap of the burette was not closed immediately as soon as the solution turned pale pink which caused the color intensity of the solution to be slightly lighter or darker. This would have provided inconsistent values when recording the final reading and initial reading of permanganate solution in the burette. To improve this error, the tap of the burette should be tightened to decrease the rate of droplets of permanganate solution dropping from the burette. This will make it easier for the student to completely stop the titration as soon as the end point of the solution is detected. Finally, not transferring the
While the solution dissolved, 50 mL of distilled water was added to a 150 mL beaker and heated on the hot plate. When the solution started to boil 2.65 grams of Na2SiO3*5H2O was added to the beaker with a stir bar and heated to a gentle boil. When both solutions began to boil, the sodium silicate solution was slowly added to the sodium aluminate. The solution was kept at 900C for 60 minutes and stirred with stir bar. After 60 minutes, the zeolite solution was cooled for 5 minutes and for the magnetized zeolite , 0.78 grams of FeCl3 and 0.39 grams of FeSO4*7H2O was added to the flask and stirred until the iron parts dissolved.
Consequently, it induces second element to be oxidized. 2. In the experiment #3, zinc electrode acts as anode, where the oxidation processes occur, while iron half-cell acts as cathode, where the reduction processes appear. In the experiment #4, iron is visa verse reducing agent that evicts electrons to copper half-cell through the circuit.
Question 4: List the 3 errors; • Adding too many drops of NaOH at the same time would affect the results because we can’t determine the exact equivalent point when the color changed. The results won’t be accurate and that will affect all the data that are dependent on the amount of NaOH to titrate. • Other error could be the hardness to notice a color change; we always use a white paper under the flask to determine when the color changes right away. And if we don’t use the white paper it will be hard to determine the color change and the amount of NaOH that was used to titrate it. • Also other source of error could be by not rising the burette with NaOH before we fill up with it, or it maybe they were rinsing it with a lot of NaOH which could affect the data recording for NaOH amount of titration.
Next, about 10 mL of both solutions, Red 40 and Blue 1, were added to a small beaker. The concentration of the stock solution were recorded, 52.1 ppm for Red 40 and 16.6 ppm for Blue 1. Then, using the volumetric pipette, 5 mL of each solution was transferred into a 10 mL volumetric flask, labelled either R1 or B1. Deionized water was added into the flask using a pipette until the solution level reached a line which indicated 10 mL. A cap for the flask was inserted and the flask was invented a few times to completely mix the solution. Then, the volumetric pipette was rinsed with fresh deionized water and
Lastly, the unknown compound was reacted with two different salts. For the first salt, 0.50 grams of KCl was mixed with 5 mL of water in one beaker while 0.5 grams of NaNO3 was mixed with 5 mL of water in a different beaker. Then, the NaNO3 solution was added to the KCl solution. To perform the reaction with the second salt, 0.50 grams of KCl was mixed with 5 mL of water and 1 mL of 1 M Ag(NO3)2 was added. After performing each reaction, the solution was observed to see if a reaction occurred and the pH value of the resulting solution was tested using a pH
In a clean test tube 8.9ml of deionized water, 0.1 guaiacol, and 0.1ml enzyme solution. There was not supposed to be anything that happened after doing this so move to the next step. Next was adding 0.3ml of hydrogen peroxide, then cover it with dura-film to invert the solution. Then fill the cuvette 2/3 full and put it in the colorimeter. So at this point the stopwatch should be ready to start time then record results every 15 seconds.
After a while, a brownish color substance started to form on the three iron nails. We predicted that the brown substance on the nails is copper because the reaction of copper(II) chloride with iron is a single displacement reaction, so copper would be produced. 0.48 grams of iron was used in the reaction because 2.73 grams subtracted by 2.25 grams is 0.48 grams. The 0.48 grams of iron had to be used in the reaction with copper(II) chloride in order to produce copper, according to the reaction equation: CuCl2+FeFeCl2+Cu. 0.52 grams of copper was produced after pouring out the copper(II) chloride solution and the three iron
It is because the volumetric pipette shows a better accuracy than using a beaker and transferring it to graduated cylinder just to have 10 ml of your solution. In comparison to that, 5.0 ml of acetic anhydride was measured through the use of an accurate pump and not by a different apparatus. In short, through the use of specific apparatuses, which provides an accurate measurement, correlates to my quantitative values which are concise. The purity of the ASA solution that we produced was determined by
Purpose: The purpose of this lab is to titrate an unknown solid acid (KH2PO4) with a standardized sodium hydroxide solution. After recording and plotting the data, the acid’s equivalence point will be recorded once the color changes. Using the equivalence point, the halfway point will be calculated, which is used to determine the acid’s equilibrium constant. The acid’s calculated equilibrium constant will be compared with the acid’s established pKa value.
As had doing the baseline prior to changing the pH with a drastic qualitative and quantitative data change, seeing no color change and slope in the graph was concerning. However as multiple trials were completed and results were compared to other classmates, more confidence arose in the results as the numerous trials with similar results ensured validity. If there were things that could have been done differently, more precision and caution would have been taken whilst doing the lab; for example: re-reading the lab before beginning and taking time while measuring out solutions. The experiment had a few errors due to human error as well as random ones. For example, in one trial, distilled water was gathered through the hydrogen peroxide pipetter, creating a chance of error due to the cross-contamination of solutions.
Conclusion: Based on the results of molarity from Trials 1, 2, and 3, it is concluded that our experimental for each trial is .410M NaOH, .410M NaOH, and .450M NaOH. The actual molarity of the NaOH concentration used was found to be 1.5M NaOH. The percent error of the results resulted in 72%. The large error may have occurred due to over titration of the NaOH, as the color of the solution in the flask was a darker pink in comparison for the needed faint pink. Discussion of Theory:
The unknown solution contained 20+ -0.05 mL of the unknown in a 40 mL beaker. A 10 mL graduated cylinder was used to accurately measure. The pH value of the unknown was recorded, and then the probe was removed again and cleaned. Last, the pH probe was placed into potassium nitrate. The potassium nitrate was contained in a 40 mL beaker, .520
The actual data is the result on our experiment vs theoretical, which is based on the calculations above. I have also learned to pay more attention to draining out all of the product completely before continuing to test the experiment, as any small drop of contaminant can veer our results into a different
Acids are proton donors in chemical reactions which increase the number of hydrogen ions in a solution while bases are proton acceptors in reactions which reduce the number of hydrogen ions in a solution. Therefore, an acidic solution has more hydrogen ions than a basic solution; and basic solution has more hydroxide ions than an acidic solution. Acid substances taste sour. They have a pH lower than 7 and turns blue litmus paper into red. Meanwhile, bases are slippery and taste bitter.
That caused a new initial reading of NaOH on the burette (see Table1 & 2). The drops were caused because the burette was not tightened enough at the bottom to avoid it from being hard to release the basic solution for titrating the acid. The volume of the acid used for each titration was 25ml. The volume of the solution was then calculated by subtracting the initial volume from the final volume. We then calculated the average volume at each temperature.