The Concentration of Potassium Hydrogen Phthalate - Essay Example

Introduction: In this experiment, the researcher aimed to know the concentration of KHP and that of two unknown solutions of acid using titration. Three substances were used in this experiment. KHP, an unknown 241 acetic acid, and an unknown 102 sulfuric acid were all titrated with NaOH. In the experiment, it was impossible to find an equivalence point without using an indicator substance. It was supposed to signal the titration reaction’s end point when it is reached, however, the solutions turned out to be light pink in the experiment. The KHP’s molar mass was calculated to find the concentration. After this, the molar mass of KHP was used to divide the number of grams (KHP) by it that generated the KHP’s number of moles. Next, the volume was calculated after titration. Next, the molarity was calculated using the formula given below: Procedure: First Part: To find the molarity of NaOH The first part of the experiment was to find the molarity of NaOH. It was done by titrating it with KHP. 1.0 g of KHP was measured and then it was dissolved in 70-75 mL distilled water. As the next step, 1 to 5 drops of phenolphthalein was added to the solution. It was done to ensure the change in color after addition of base (NaOH). Next, KHP was dissolved as much as possible in order to get accurate results. After that, the base was dripped into the acid using a buret which was filled with NaOH up to a certain volume. It was done until the color started changing noticeably. A white paper was placed under the glassware to see the change in color clearly. The solution started turning into pink color which was also the end point of the reaction. Next, the volume was calculated after stopping the buret using the formula: . This step was repeated for two more times to get the lightest color. The NaOH volume was also recorded each time. Second Part: To find the molarity of () The equation is given below: In this part of the experiment, 2.0 mL acetic acid was measured and poured in a 10 mL graduated cylinder. After this, the exact volume was noted and mixed with 70-75 mL water. As the next step, the graduated cylinder was rinsed before adding water in the acid. Next, 1 to 5 drops of phenolphthalein were added to the solution. After this, titration was started slowly in order to avoid a dark pink color. Then, the volume was noted just upon turning of the solution into a light pink color and this was also the end point of the reaction. Next, the volume was calculated using the formula: . This step was also repeated for one more times to get the lightest color. The volume was also recorded each time. Third Part: To find the molarity of () The equation is given below: In this part, 2.0 mL sulfuric acid was measured and poured in a 10 mL graduated cylinder. After this, the exact volume was noted and 70-75 mL of water was mixed. Next, the graduated cylinder was rinsed before adding water in the acid to ensure pouring of all leftovers in the solution. After this, 1 to 5 drops of phenolphthalein were added to the solution. After this, titration was started slowly in order to avoid a dark pink color. Then, the volume was noted just upon turning of the solution into a light pink color and this was also the end point of the reaction. Next, the volume was calculated using the formula: . This step was also repeated two more times to get the lightest color. The volume was also recorded each time. After this, the equipment used and the work area were cleaned and solutions were disposed off in waste bucket. Discussion: Titration is very effective in determining the unknown concentration of a known reactant. The volume of each substance of the known concentration needs to be written down in order to determine the level of unknown concentration. An important point here is that the equivalent point is extremely difficult to be observed because of which an indicator substance needs to be used to signal the end point. It is due to this reason that phenolphthalein was used in this experiment as the indicator substance. NaOH, which was used as the base, is hygroscopic and KHP is titrated with it to find the level of concentration. As Table 1 reveals, 1.0 gram KHP has in it 0.00489 moles of KHP. The equation in part one reveals the 1:1 ratio, which shows the existence of 00489 moles of NaOH. As far as the average molarity is concerned, the three trials indicate this value to be 0.1985 M of NaOH. NaaOH determines the molarity of sulfuric and acetic acids by acting as a base. The trials’ percentage error of below 1% shows the precision and accuracy of the calculations. Given below is the equation used for the calculation of molarity of solution with identified volume and number of moles: In table 2, the researcher made use of 4.55 mL and 5.0 mL of NaoH solution to titrate 2 mL acetic acid. As there was 1:1 ratio, 0.000903 moles of NaOH acid were there for the first trial and 0.000794 moles for the second trial. The level of concentraton can be identified as volume and molarity of the acetic acid are known. As far as the average molarity of the acetic acid driven from the trials is concerned, it was 0.4243 M. The percentage error of 40% to 60% shows that calculations were accurate but lacked precision. In table 3, the researcher made use of 11.0 mL and 10.6 mL of NaoH solution to titrate 2 mL sulfuric acid. As there was 1:2 ratio, 0.00109 moles of NaOH and sulfuric acid were there for the first trial, whereas 0.00105 moles for the second trial. The level of concentraton can be identified as volume and molarity of the sulfuric acid are known. As far as the average molarity of the sulfuric acid driven from the trials is concerned, it was 0.535 M. The percentage error of 5% to 9% shows that calculations were accurate, as well as precise. Conclusion: Summing it up, the recorded calculations reveal that titration is an effective and appropriate way to find the level of concentration. As the goal of this experiment was to find the concentration using titration, the method turned out to be very efficient and effective considering the percentage error which matched the results of the reactions done in the experiment. Read More