Methyl Orange Essay

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In this case methyl orange can be used as the indicator, pH arc being 3,1...4,4, or methyl red, pH arc being 4,4...6,2. If the pH value is bigger than the arc then the indicators will give a yellow colour to the solution, if smaller then a red colour.
Total hardness is the sum of amount of Ca2+ and Mg2+ ions and is determined via complex-titration. Here is the stoichiometric point found by using different complex ions with different colours. The solution is titrated with ethylenediaminetetraacetic acid disodium salt or in other words with trilone-B solution which can be simply notated as Na2H2Y
Na2H2Y → 2Na+ + H2Y2–
Chromogen black ET-00 (eriochrome black T) is used to determine the total hardness of water. Along with the Ca2+ and Mg2+ ions it forms a lilac purple complex ion. So after adding the buffer solution and indicator ET-00, the solution containing Ca2+
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The first was determinging the carbonate hardness. I started the experiment with washing the 100 cm3 pipette 2 times with a small amount of the test water. Then I washed the conical flask with distilled water and pipetted into the conical flask 100 cm3 of the test water. After that I added 3 drops of indicator mo or mr. The next step was preparing the burette, hence I removed any air bubbles from the nozzle and filled it with 0,025 M hydrochloric acid till zero (the lower meniscus has to coincide with the scales 0-notation). Then I titrated the water sample with a 0,025 M hydrochloric acid solution, while stirred the water in the flask with intense circular movements. At the stoichiometric point, the colour of the water changed from yellow to pink red. I then read the consumed volume of hydrochloric acid for titration from the burette with a 0,05 cm3 precision. The las experimental step was to wash the conical flask carefully with distilled water and to repeat the titration with a new amount of water. After this the following data was

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