Determination of Chlorine and Iodine in Water Essays

Determination of Chlorine and Iodine in Water Essays Determination of Chlorine and Iodine in Water Essay Determination of Chlorine and Iodine in Water Essay I. Introduction The intent of this research lab was to find the sum of Cl and I in a sample of H2O by titration utilizing a amylum index and to standardise a Na thiosulfate solution. Chlorine is added to municipal H2O supplies to sublimate it plenty to go safe to imbibe. Iodine is besides added to H2O when people camp or go boosting in the back state where they can non convey purified H2O along. Chlorine and I are added to kill micro-organisms in H2O. Oxidation reactions occurred in this experiment. The Chlorine was oxidized because it lost negatrons in the reaction. The I was reduced because it gained negatrons. The solutions turned a xanthous colour because of the I which disappears one time all of the I has reacted in the titration. Sodium thiosulfate was the titrant in the procedure of titration. It was added to respond with the I in the solution. Starch was added to give the solution a bluish colour near the end point of the titration. Potassium iodate ( KIO? ) was used to standardise the Na thiosulfate solution. Practical applications would include proving unknown samples of H2O and municipal H2O supplies for the concentration of chlorine nowadays because excessively much can do wellness jobs and non taste good. Not plenty added. wouldn’t kill the micro-organisms in the H2O to do it safe to imbibe. II. Procedure First the standardisation of Sodium Thiosulfate was completed. A 50mL buret was obtained and rinsed twice with the Na thiosulfate solution. It was so filled with the solution. The tip of the buret was checked to do certain there weren’t any bubbles in it. Then a 250mL beaker was obtained. A 25mL pipette was used to add precisely 25mL of the KIO? solution. Then 50mL of deionized H2O and about. 25g of solid KI was added. The solution was stirred until the solid was wholly dissolved. 2mL of glacial acetic acid was so added. Then. the beaker was placed under the buret and was swirled as the Na thiosulfate was added. The buret was slowed as the colour became lighter. When the colour was about gone. 1mL of the amylum solution was added to turn the solution blue. Then it was easy titrated until the colour disappeared. The concluding volume of the solution in the buret was recorded and the sum of titrant was calculated. This titration was repeated two more times to standardise the con centration of the thiosulfate. Then the concentration of Chlorine in Tap H2O was found. It was repeated the about precisely the same manner as earlier. The buret was filled with the Na thiosulfate solution and the initial value was recorded. Then a 50mL calibrated cylinder was rinsed with tap H2O two to three times. The calibrated cylinder was so filled with cold pat H2O. It was so poured into a clean beaker and. 25g of KI and 2mL glacial acetic acid were added and stirred until the solid was dissolved. Then the solution was titrated. 1mL of amylum was added so the yellow colour about disappeared. It was so titrated easy until the bluish colour disappeared. The concluding volume was recorded and the volume of titrant used was determined. This was repeated two more times. Then the concentration of I was determined in the I purified H2O. The buret was refilled and the initial volume was recorded. Then the 50mL graduated cylinder was rinsed with the iodine solution. 50mL of the iodine solution was so obtained and poured into a clean beaker. Then. 25g of KI and 2mL of acetic acid were added and the solution was stirred until it was dissolved. Then it was titrated until the xanthous colour about disappeared. 1mL of amylum was so added and the solution was titrated easy until the bluish colour disappeared. The concluding volume was recorded and the volume of titrant used was so determined. This was repeated two more times. Then everything was cleaned and put away. III. Data and Results Table 1: Standardization of Sodium Thiosulfate Solution | Initial Buret Volume ( milliliter ) | Concluding Buret Volume ( milliliter ) | Volume Used ( milliliter ) | 1st Standardization| 50| 25. 64| 24. 36| 2nd Standardization| 50| 25. 99| 24. 01| 3rd Standardization| 50| 26. 21| 23. 79| Table 2: Titration of Tap Water | Initial Buret Volume ( milliliter ) | Concluding Buret Volume ( milliliter ) | Volume Used ( milliliter ) | 1st Titration| 50| 48. 29| 1. 17| 2nd Titration| 50| 48. 25| 1. 75| 3rd Titration| 50| 48. 20| 1. 80| Table 3: Titration of Iodine Solution | Initial Buret Volume ( milliliter ) | Concluding Buret Volume ( milliliter ) | Volume Used ( milliliter ) | 1st Titration| 50| 45. 61| 4. 39| 2nd Titration| 50| 45. 59| 4. 41| 3rd Titration| 50| 45. 60| 4. 40| Table 4: Average Concentrations | Molarity ( moles/Liter ) | Sodium Thiosulfate Solution| 1. 06?10?| Chlorine in Tap Water| 1. 86?10?| Iodine in Solution| 4. 66?10?| Sample Calculation- Concentration of Chlorine ( 1. 06?10? ) * ( 0. 00175L ) =1. 86?10? moles thiosulfate ( 1. 86?10?mol thiosulfate ) * ( 1 mol Cl/2 mol thiosulfate ) =9. 28?10? mol Cl ( 9. 28?10?mol Cl ) / . 05L=1. 86?10? moles Cl/Liter In the first standardisation of the Na thiosulfate solution. 24. 36mL of the titrant was used. 24. 01mL and 23. 79mL were used for the 2nd and 3rd standardisations. With the concentration of the Na thiosulfate solution divided the mean volume of those gave the mean thiosulfate concentration which was 1. 06?10? moles per litre. For the titration of tap H2O. an norm of 1. 75mL of the Na thiosulfate solution was used. After the computations. the concentration of Cl in tap H2O was 1. 86?10? moles of Cl per litre. The norm of the titrations of the iodine solution was 4. 40mL of titrant used. After the computations. 4. 66?10? moles of I were present per litre. Some utile observations were conducted. The I in the solution made it turn a xanthous colour when the glacial acetic acid was added. It started to vanish as the I was responding with the titrant. When the amylum solution was added. the solution turned bluish. As the end point neared. the bluish colour started to disperse. When the end point was reached. the solution was clear with no colour left in the solution. Beginnings of mistake could include adding excessively much titrant from the buret into the solution. IV. Decision The intent of this lab was to place the concentration of Cl and I in different samples of H2O. The consequences fulfilled the intent of this lab because the concentrations of Cl and I were found. The concentration of Cl in the tap H2O was 1. 86?10? moles of Cl per litre. The molar concentration of I in the iodine H2O solution was 4. 66 x10? moles per litre. The concentration of I was significantly higher than the sum of Cl in tap H2O. There was more I in the H2O because of the solid KI being added to the solution. Tap H2O contains little sums of Cl because that’s all that is needed to kill the micro-organisms populating in the H2O that are harmful to people. The consequences that were obtained were unexpected because there wasn’t a standard value to travel off of. The per centum mistake wasn’t able to be obtained. Possible beginnings of mistake would include adding excessively much of the titrant to the solution. This would impact the consequences by holding more than adequate titrant used. This would impact the concentration values and do them higher than they truly were. Chemical constructs used were titrations. When the Iodide ions. from the K iodide. react with the Cl in the tap H2O. chloride ions and I? were formed. Then the I? was titrated with the Na thiosulfate solution which created the iodide ions. Before the end point of the titration. the amylum was added. Once all of the I reacted with the thiosulfate. the bluish colour disappeared because the end point was reached and the iodide ions were formed. Besides the standardisation of the Na thiosulfate solution was performed. When the K iodate reacted with the solid KI and the acetic acid. it created I? and H2O. The I? was titrated and formed with the thiosulfate and created iodide ions besides. The concentration of the thiosulfate was 1. 06?10? moles per litre. That consequence was expected because it should hold been about. 001 M and it was. 00106 M.