Test method for mixed catalyst solution of cobalt acetate, manganese acetate and hydrobromic acid (6)

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In an acidic medium, barium ions and sulfate ions in the sample produce insoluble barium sulfate precipitates, making the sample solution turbid.

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Weigh 10g or an appropriate amount of sample, accurate to 0.

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Add 3mL ethanol and 5mL barium chloride solution to the remaining sample solution colorimetric tube .

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The iodide (I-) in the sample is oxidized to elemental iodine by ferric chloride, and the elemental iodine is extracted with trichloromethane.

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2 Reagents

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1 Trichloromethane
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2 Ferric chloride solution: 100g/L, weigh 10g of ferric chloride, accurate to 0.
1g, place in a 50mL beaker, dissolve with water, transfer to a 100mL volumetric flask, dilute to the mark, and mix
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Prepare this solution before use
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3 Iodide (Ⅰ-) standard solution: 0.
1mg/mL
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3 Analysis steps

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1 Preparation of standard colorimetric solution

Weigh 20g or an appropriate amount of sample, accurate to 0.
1g, place it in a 50mL beaker, transfer 40mL of water to a 250mL separatory funnel towel, add 5.
0mL of ferric chloride solution, mix well, add 10mL of chloroform , and leave for 5min.
Shake for 1 min, stand still for layering, discard the organic phase, repeat the above operation until the organic phase does not appear purple, and separate the water phase into a separatory funnel
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Accurately add an appropriate amount of iodide (Ⅰ-) standard solution, add 5.
0mL ferric chloride solution, 10mL chloroform, let stand for 5min, shake for 1min, let stand for layering, discard the water phase, and divide the organic phase into 25mL Colorimetric tube
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The amount of iodide (I-) standard solution added should be determined according to the limit value of the iodide content of the sample.
The principle of the added amount is that the color of the standard colorimetric solution should be close to or darker than the color of the sample solution
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2 Determination of sample solution

Weigh 20g or appropriate amount of sample: accurate to 0.
1g: place in a 50mL beaker, transfer to a separatory funnel with 40mL water, add 5.
0mL ferric chloride solution and 10mL chloroform, the following is the same as the standard colorimetric solution The method of processing and horizontal visual color comparison with a white background
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