DIPLOMA IN INDUSTRIAL CHEMISTRY (AS115) CHM 312 LABORATORY REPORT (MAJOR PROJECT) EXPERIMENT TITLE: DETERMINATION OF POTASSIUM IN FERTILIZER NAME: NURSYAHIRAH BINTI ABDUL RAHIM (2011825426) GROUP: ASD5Dg LECTURER’S NAME:
ENCIK ZAILUDDIN BIN ARIFFIN DATE OF EXPERIMENT: th 19 AUGUST 2013 DATE OF SUBMISSION: th 30 SEPTEMBER 2013
ABSTRACT: The element that is to be determined is potassium in fertilizer by using Atomic Absorption Spectroscopy. The fertilizer is obtained from three different brands which are Tani, TST and Serbaguna that act as fruit inducer for plantation. The standard calibration curve is used to plot all concentrations of standard solution in order t o get correlation coefficient that is 0.9991. The correlation coefficient must get triple nine to shows the accuracy of experiment. The standard solution was prepared for concentration of 1 ppm,3 ppm,5 ppm, 7 ppm and 9 ppm. After that, three samples were prepared by using dilution factor method. The samples were diluted in 250 mL and 100 mL volumetric flask. There are two sets of results that needed to be obtained to compare which result is the best. Three trials were ran for every brands for one set. The average concentration obtained for Tani, TST and Serbaguna for first set is 2.4106 ppm, 0.2800 ppm and 8.5859 ppm respectively. For second set, the average concentration for three samples from difference brands is 2.4216 ppm, 0.2804 ppm and 8.5758 ppm. The amount of potassium that contains in the fertilizer for brand Tani, TST and Serbaguna is 24.06%, 2.80% and 85.76% by weight respectively for the first set. For second set, the amount of potassium in three different brands is 24.13%, 2.80%, and 85.52%. Fertilizer from Serbaguna shows the larger amount of potassium compared fertilizer from TST and Tani. INTRODUCTION: Atomic Absorption Spectroscopy (AAS) is an instrument used for qualitative and quantitative to determine several elements in given sample. This instrument involves four difference processes which are nebulization, atomization, aspiration and volatilization. The solution will be aspirated and nebulized to convert a liquid into fine spray or mist called aerosol. Volatilization occurs where a liquid is convert into gaseous state. Atomization is process of converting liquid into gas phase atoms or elementary ions.The flame AAS used in laboratory UiTM Arau, Perlis is oxygen-acetylene . The most common source for atomic absorption measurements is the hollow cathode lamp. The cathode is made of metal of interest. It means t hat the different lamp for each element. If the sample analyzed is potassium, so the hollow cathode lamp that will use is potassium also. Hollow cathode lamp is used to maximize probability of redeposition on cathode and also restricts the light direction. The detector used is photomultiplier tube which can detect the element that need to be determined. However, this instrument can detect varies element that range from parts per billion (ppb) to parts per million (ppm). The advantages of using AAS are speed, convenience, unusually high selectivity and moderate costs. The disadvantages are its sensitivity varies with element, must maximize burner position and can detect only one element in one time. In this experiment, the element analyzed is potassium in fertilizer. The fertilizer used act as fruit inducer which the brands comes from Serbaguna, TST and Tani . Potassium is a trace element found in fertilizer which is 17% by weight based on Nitrogen-PhosphorusPotassium (NPK) rating. Agriculture is the sector which uses the most amount of fertilizer for plants production. There are many uses of potassium for plantation which are regulation of water and nutrients movement in plant cells, promotes flowering and fruiting of the plants,
stimulates of an early growth, increases protein production, and improves resistances to diseases and insects. OBJECTIVES: 1) To determine the amount of potassium contains in fertilizer by using the standard calibration curve. 2) To compare the experimental results with the values listed on the manufacturer’s label. PROCEDURE: A) Preparation of Standard Solutions 1. 10 ml of 1000 ppm stock solution was pipetted. It was then transferred into 100 ml volumetric flask and it was diluted with deionized water to the mark. This solution was labeled as 100 ppm. 2. 0.5 mL from 100 ppm solution was measured and was transferred into 50 mL volumetric flask. It was diluted to the mark. 3. This solution was labeled as 1 ppm. 4. By using the 100 ppm and 50 volumetric flask, a series of standard solutions having the following concentrations were prepared which are 3 ppm, 5 ppm, 7 ppm, and 9 ppm. B) Preparation of sample (Tani, TST, and Serbaguna) 1. The fertilizer was grinded by using pestle and mortar. 2. By using analytical balance, it was weighed approximately of 2.5 g. 3. Then, the sample was dissolved with 150 mL deionized water in 250 mL beaker. 4. The solution was placed on a hot plate and boiled for 30 minutes. 5. It was then allowed to be cool and stirred thoroughly. 6. The solution was transferred into 250 mL volumetric flask and diluted to the mark. 7. It was filtered by gravity. 25 mL from the filtered solution was pipet into a 100 mL volumetric flask. The solution was diluted to t he mark. 8. The sample solution prepared was run for three times in order to obtain precision results. RESULT AND CALCULATION: 1) Preparation of Stock solution: M1V1 = M2V2 (1000ppm) V1 = (100ppm)(100mL) V1 = (100ppm)(100mL) (1000ppm) V1 = 10 mL
2) Preparation of Standard solutions: Standard 1 (1ppm), M1V1 = M2V2 (100ppm) V1 = (1ppm)(50mL) V1 = (1ppm)(50mL) (100ppm) V1 = 0.5 mL 3) Sample’s calculation (Tani): Average concentration obtained: = 2.4336 + 2.4033 + 2.3949 3 = 2.4106 mg L The amount of K in sample (%wt/wt): =2.4106 mg X 0.25 L L = 0.60265 mg X 100 2.505 g = 24.06 %
Brands
Tani TST Serbaguna
Brands Tani TST Serbaguna
Run 1 2.4336 0.2809 8.5903
First trial (mg/L) Second trial (mg/L) Run Run Average Run Run Run Average 2 3 1 2 3 2.4033 2.3949 2.4106 2.4224 2.4237 2.4186 2.4216 0.2802 0.2790 0.2800 0.2827 0.2808 0.2778 0.2804 8.5879 8.5794 8.5859 8.5887 8.5797 8.5589 8.5758 Table 1
First trial Mass (g) % weight/weight 2.505 24.06 2.504 2.80 2.503 85.76 Table 2
Second trial Mass (g) % weight/weight 2.509 24.13 2.508 2.80 2.507 85.52
DISCUSSION: This experiment was conducted to determine the actual amount of potassium in three different brands of fertilizers and to compare the experimental results with the values listed on the manufacturers’ label. In this experiment, we use fertilizer as a sample from brand of Tani, TST and Serbaguna. After it was grounded, we weighed approximately about 2.5 g and dissolved it with 150 mL deionized water . Then, the solution was boiled for 30 minutes to dissolved the fertilizer completely. The solution of sample was diluted and filtered to remove precipitate in the solution in order to obtain clear solution. When boiling process occur, the colour of sample solution from brand Tani is browngrey, TST is light blue while Serbaguna is very light blue. Dilution process was done for three times. This dilution method is called dilution factor. The dilution process give colourless solution for three samples. In order to obtained the concentration of sample in the standard range, 5.90 mL from dilution in 100 mL volumetric flask was measured and diluted in 250 mL volumetric flask. Two set of trials for every brands were conducted to compare which result is the best one and also to see whether the condition of sample is change. The samples are run for three times for one set of trial to get the average reading as recorded in Table 1. The standard solution was prepared for five different concentrations which are 1 ppm, 3 ppm, 5 ppm, 7 ppm and 9 ppm. This standard solution was run to obtained correlation coefficient that is 0.9991 before run the samples. This result can be shown from graph of standard calibration curve which the absorption is directly proportional to the concentration. The percentage by weight of potassium for every brands of fertilizer were calculated and compare to manufacturer’s label. The amount of potassium calculated is shown in Table 2 which are more than 17% by weight when compared with manufacturer’s label. However, fertilizer from brand Serbaguna has a higher amount of potassium than the two brands for two sets.The values obtained were shows a greater differences from label because of some error while carried this experiment. First, the three samples are not grinded very well and same size. This gives difference rate of reaction as difference surface area. Maybe some of potassium does not breaks down completely and gives different amount of potassium. Second, the solution was measured by using measuring cylinder which gives inaccurate value. Third error is there have a slight variations in the eyes level while taking measurement in measuring cylinder and burette which means eyes is not perpendicular to meniscus in these apparatus. The result shows that the concentration of potassium and weight of sample are precise among three runs of both sets. The percent by weight also gives similar values for both sets. In order to get this precision values, some precautions are needed to be aware and take note. All glasswares used such as burette, beaker, volumetric flask and so on must be rinsed and calibrated first before using them. The burette was ensured that there is no bubble in the tip that will affect the reading obtained. . For this experiment, do not use distilled water to dilute the standard and the sample, but use deionized water for dilution. Deionized water is used in this experiment because it does not contain any charge. So that, there is no attraction between difference charge of ion and thus affect the result. The scale of the analytical balance must be set correctly based on the experiment.
CONCLUSION: The amount of potassium that contains in the fertilizer for brand Tani, TST and Serbaguna is 24.06%, 2.80% and 85.76% by weight respectively for the first set. For second set, the amount of potassium in three different brands is 24.13%, 2.80%, and 85.52%. Fertilizer from Serbaguna shows the larger amount of potassium compared fertilizer from TST and T ani. REFERENCES: 1) Analytical Methods for Atomic Absorption Spectroscopy, 12th August 2013, retrieved from, http://www.lasalle.edu/~prushan/Intrumental%20Analysis_files/AAPerkin%20Elmer%20guide%20to%20all! .pdf 2) NPK rating, 12th August 2013, retrieved from, http://en.wikipedia.org/wiki/NPK_rating 3) D.A. Skoog, D.M. West, F.J. Holler, S.R. Crouch, Fundamentals of Analytical Chemistry(8th Edition), Chapter 28: Atomic Spectroscopy, page 839-863.
