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Design of the Experiment – Revised ENGINEERING CHEMISTRY LABORATORY DESIGN OF THE EXPERIMENTS By DEPARTMENT OF CHEMISTRY Maharaj Vijayaram Gajapathi Raj College of Engineering (Autonomous) (Approved by AICTE, New Delhi, and permanently affiliated to JNTUK) Chintalavalasa, Vizianagaram -535005 (A2 REGULATION) S. No. Contents Page. No. 1 Determination of total hardness of water. 03-06 2 Determination of percentage of CaO in cement 07-16 3 Determination of acid number and saponification number of oil/ 17-25 lubricants. 4 Determination of acid strength in lead acid battery 27-32 5 Adsorption of acetic acid on activated charcoal 33-38 6 pH metric titration of strong acid using a strong base 39-52 7 Condcutometric titration of strong acid using a strong base 53-59 8 Condcutometric titration of weak acid using strong base 60-63 9 Determination of percentage of iron in cement by colorimetry 64-69 10 Potentiometric titration of Fe+2 using potassium dichromate 70-75 11 Preparation of polymer (Thiokol rubber) 76-78 12 Determination of viscosity of a polymer solution using survismeter 79-82 13 Preparation of nano materials( Zn/ Mg- ferrite) 83-87 COMPLEXOMETRY DETERMINATION OF TOTAL HARDNESS OF WATER Objective ● To know the experimentation and process involved in the determination of hardness of water Outcomes By using the above procedure student can carrying out and execute, the process of determination of hardness of water experiment Student can able to identify the type of water and it’s suitability to various applications APPARATUS & CHEMICALS REQUIRED: Burette, pipette, volumetric flasks, funnel, conical flasks, wash bottle, with distilled water, burette stand, EDTA solution, zinc sulphate AR(solid), Eriochrome black T (EBT) indicator solution, buffer solution (NH4Cl +NH4OH) of pH 10. Theory: The total hardness of water is generally due to dissolved calcium and magnesium salts. Hardness of water is the expression for the sum of the calcium and magnesium ion concentration in a water sample. The standard way to express total hardness of water is in ppm. Ethylene diamine tetra acetic acid (EDTA) form a complexes with Ca2+ and Mg2+ ions, which are more stable at pH 10. The success of an EDTA titration depends upon the precise determination of the end point. Ordinary indicators fail hence metal ion indicators or metallochromic indicators like SBT (Solochrome Black-T), EBT (Eriochrome Black T) are used. The indicator reacts with Ca+2 and Mg+2 ions to give a wine red color. As EDTA is further added, the free Metal ions (Ca+2 and Mg+2) present in the water sample are first complexed to EDTA forming the most stable M- EDTA complex. The extra drop of EDTA added, forms a pale blue color, which indicates the end point of the titration. EBT Structure Principle: M2+ + EBT [M-EBT] (Wine Red) M-EBT] + EDTA [M-EDTA] + EBT (Colorless) 3 S. No Hardness (ppm) Type of water Application 1 up to 50 Soft Industrial 2 51-100 Moderately Soft Laundry 101-150 Slightly Hard 3 151-250 Moderately Hard Agriculture 4 251-350 Hard 5 over 350 Excessively Hard Drinking *Above data is as per WHO and BIS PROCEDURE: PART A – Preparation of 0.01M EDTA solution: About 0.845 g of EDTA is transferred into a 250ml volumetric flask through a glass funnel. The substance is dissolved completely in a minimum amount of distilled water and the solution is made up to the mark. OBSERVATIONS: S. No Contents in the pan Grams Milligrams Total weight(g) 1 W1 2 W2 CALCULATIONS: W1 = Weight of weighing bottle with EDTA = g W2 = Weight of weighing bottle after transferring the EDTA = g Amount of the EDTA transferred = W1–W2 = g Concentration of the EDTA = x = M Gram molecular weight (GMW) of EDTA = 338.22 g PART B –Determination of total hardness of water: 20.0 ml of the water sample is pipetted out into a clean conical flask to this add 3ml ammonia buffer solution and 1 or 2 drops of EBT indicator, this produces wine red color. Titrate with EDTA solution from the burette until the color changes from wine red color to pale blue. 4 OBSERVATIONS: S. No Volume of water sample taken in ml Burette Reading Volume of EDTA Initial Final rundown in ml 1 Sample 1 2 Sample 2 3 Sample 3 CALCULATIONS: Volume of water sample taken = 20ml Volume of EDTA rundown = Total hardness in CaCO3mg/lit is given by the formula: Volume of EDTA X Conc. of EDTA X100.1 X1000 Total hardness of water = ----------------------------------------------------- ppm Volume of water sample titrated REPORT: The given water samples contains the following ppm (parts per million) of total hardness. 1. Sample 1 ……… ppm 2. Sample 2 ……… ppm 3. Sample 3………. ppm SIGNIFICANCE OF THE EXPERIMENT Hardness of water has a permissible limit for use in laundering purpose and industrial applications, so this experiment assumes importance in the analysis of the water samples from time to time, so that the water has the desired quality parameters. If not, proper rectifications can be made to change the quality of water, based on the requirements. This data is relevant for knowing the quality of water for other purposes in industrial equipment such as boilers, house old equipment, heaters, water pipes etc. Questions: Based on the Hardness of water (ppm), would you say your water is soft, moderately hard, hard or very hard? Give a very brief explanation while addressing the following questions. 1. What is hard water? 2. Which causes hardness to water? 3. How is water classified based on the degree of hardness? 5 4. List the types of hardness present in water 5. State the salts responsible for temporary and permanent hardness of water 6. What is meant by softening of water? 7. What is EDTA? 8. Why is disodium salt of EDTA preferred to EDTA for estimation of hardness? 9. What is EBT ? 10. What is a buffer solution? Give an example. 11. Why is ammonium hydroxide-ammonium chloride buffer added during the determination of hardness of water? 12. Mention the disadvantages of hard water for industrial purpose. 13. List the methods of determining hardness of water. 14. What is the significance of this experiment? 6 DETERMINATION OF TOTAL CALCIUM OXIDE IN PORTLAND CEMENT BY RAPID EDTA METHOD OBJECTIVES: To determine the amount of total calcium oxide in the given test sample of cement To compute the percentage of total calcium oxide. Comparison of result with the industrial standard. Result conclusion / report writing. OUTCOMES: The student will be able to determine the percentage of total calcium oxide in cement sample and can compare the experimental results with industrial standards. INTRODUCTION Cement is a binder, a substance that sets and hardens and can bind the other materials together such as sand, bricks and other building blocks. Cement contains oxides of Calcium, Silicon, Aluminum, Magnesium, Iron and Calcium Sulfate, Sulfur Trioxide and Alkali metals (in small amounts). (Percentage composition may vary depending on the grade of cement) 7 These oxides interact with one another in the kiln at high temperature to form more complex compounds. The relative proportions of these oxide compositions are responsible for influencing the various properties of the cement. Functions of Calcium oxide in the cement are It is the principal constituent of the cement. Presence of lime in a sufficient quantity is required to form silicates and aluminates of calcium. Excess of lime reduces the strength and makes the cement to expand and disintegrate. Deficiency in lime causes cement to set quickly and also reduce the strength of the cement. How do I determine the calcium oxide content in a cement sample? Calcium oxide in the cement is determined by complexometric titration method. What is a Complexometric titration? It is a form of volumetric analysis, in which formation of colored complex is used to indicate the end – point of a titration. Complexometric titrations are particularly useful in determining a metal ions or mixture of metal ions in solution. (Source: Wikipedia). These titrations are based on complexing a metal ion with a ligand (?). Ligand is an electron donating species (may be of either Organic, Inorganic and either charged or neutral). Simple complexing agents such as ammonia are rarely used as a titrating agent because a sharp end point cannot be observed due to improper complexation. The ligands having multiple donor sites are used as complexing agents. The common ligands used in the complexometric titrations are Ethylene diamine tetraacetic acid (EDTA), 1, 2-cyclohexane tetraacetic acid (CDTA), Dimethylgyloxime, Nitrilo triacetic acid etc. The accuracy of these titrations is high and the concentration of the metal ion can be determined even at millimole level. EDTA is one such good complexing agent. How to determine the end – point of the reaction in a complexometric titration? The end – point of the complexometric titration is determined by using a metal – ion indicator or complexometric indicator. Commonly used metal – ion indicators are Organic dye stuffs viz. Eriochrome Black – T, Fast Sulphon Black – F, Murexide, Calcein, Patton – Reeder’s indicator, xylenol orange etc. How EDTA is helpful in determining the Calcium oxide content in cement? 8 EDTA forms a stable complex with almost all metal ions and this reaction is the basis for general analytical method for determination of these metal ions. EDTA is ethylene diamine tetra acetic acid has four carboxylic acid groups and two amino acid groups. It is a hexadentate ligand having six donor sites. All the six donor sites will form co- ordinate covalent bonds with the metal ion and form a stable metal complex. EDTA forms 1:1 complex with metal ion present in the test sample irrespective of the valence of the metal ion. Pure EDTA is insoluble in water and EDTA disodium salt is used instead of EDTA.
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