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Experiment 1 Standardization of Acid and Base Solution

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    DIPLOMA IN LABORATORY TECHNOLOGY FACULTY OF SCIENCE AND MATHEMATICS DEPARTMENT OF CHEMISTRY UNIVERSITI PENDIDIKAN SULTAN IDRIS  ______________________________________________ SKU1013 BASIC CHEMISTRY II  ______________________________________________ LAB REPORT EXPERIMENT 4  STANDARDIZATION OF ACID AND BASE SOLUTION   NAME :MUHAMMAD AMIRUDDIN BIN MD SHAH NO. METRIC :E20171016971 GROUP : G LECTURE :EN. MOHAMAD SHAHRIZAL AHMAD TITLE Standardization of acid and base solution OBJECTIVE 1.   To know how to prepare and standardise the concentration of NaOH and HCl solution. INTRODUCTION During a titration, the volume of one reagent, the analyte (solution in Erlenmeyer flask) is predetermined while the other reagent, the titrant (in burette) slowly introduced to the analyte solution. The completion of this reaction can be determined via observation through the use of an indicator. The amount of reagents is determined  by knowing exactly volume of known molarity that required to completely react with the analyte. Knowledge on the ratio of reaction between acid and base allows determination of the other solution's Molarity. Two basic methods are used to establish the concentration of such solution. There are: 1. The direct method in which a carefully weighed quantity of a primary standard compound is dissolved in a soluble solvent and diluted to a known volume in a volumetric flask.  2. Standardization of the solution for titration analysis where the titrant (or titration reagent e.g. NaOH) need to be standardized before using for determination of the concentration of other solution. This process can be performed via titrating the titrant against. a. A weighed quantity of primary standard (in solution form).  b. A weight quantity of secondary standard (in solution form). c. A measured volume of another solution. A titrant that is standardized against a secondary standard or against another solution is sometimes referred to as a secondary standard solution. The concentration of a secondary solution is subject to a larger uncertainty than that to a primary standard solution. APPARATUS Analytical balance, weighing bottle, Erlenmeyer flask, beaker 100 mL, volumetric flask 250 mL and 500 m, pipette 20 mL and 25 mL, burette 50 mL REAGENTS Sodium hydroxide, hydrochloric acid (0.3 M), oxalate acid dehydrate, distilled water,  phenolphthalein indicator 6  PROCEDURE A) Preparation of NaOH Solution 1. Weigh a quantity of NaOH pellet by using analytical balance to prepare 500 mL solution of 0.2 M. 2. Transfer to the 100 mL clean beaker. Add enough distilled water to swirl the pellet using glass rod until homogenies. 3. Transfer the solution into the volumetric flask 500 mL and add water till the mark. Invert the flask for homogenies. B) Standardisation of NaOH with oxalate acid dihydrate 1. Weigh accurately oxalate acid dehydrate (OHP) (powder) that theoretically will completely react with 25  –   35 mL of NaOH of solution above by using analytical  balance (choose one volume of NaOH for calculate the amount of acid to be weigh). 2. Transfer the acid powder to the Erlenmeyer flask. Add distilled water to dilute the acid. 3. Add two drops of phenolphthalein indicator to the solution in the flask. 4. Prepare 3 to 4 sample. Preparation of sample at difference weigh is better and the reading should be note down. 5. Completely fill the burette with the sodium hydroxide solution and remove the air from the burette tip by running out some of the solution into an empty beaker. 6. Make sure that the lower part of the meniscus is at zero mark or slightly lower. 7. Remove any hanging drop from the burette tip by touching it to the side of the  beaker used for washings. 8. Allow the burette to stand for at least 30 seconds before reading the exact position of the meniscus. 9. Record the initial burette reading. 10. Titrate the acid solution with NaOH that you’ve been prepared in part A. Slowly add the NaOH solution to your flask of H2C2O4 solution while gently swirling the contents of the flask. 11. As the NaOH solution is added, a pink color appears where the drops of the base come in contact with the solution. The color disappears with swirling. 12. As the end point is approached, the color disappears more slowly, at which time the sodium hydroxide solution should be added drop by drop. 13. The end point is reached when one drop of the sodium hydroxide solution turns the entire solution in the flask from colorless to pink.
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