Industrial Difluorochloromethane (HCFC-22) (3)

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At room temperature, the sample is evaporated, and the mass of the high boiling point residue is weighed to obtain the evaporation residue content

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Figure 1 Schematic diagram of evaporator

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Washing liquid: dichloromethane

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After the weighing tube is dried for 30 min in an electric heating blast box at (105±2) ℃, it is cooled in a desiccator for 30 min, weighed to the nearest 0.

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The mass fraction w2 of the evaporation residue, expressed in %, is calculated according to formula (2):

Where:

m ₂ —The value of the mass of the evaporation residue, in grams (g);

m—The value of the mass of the sample, in grams (g)

Take the arithmetic mean of the two parallel determination results as the determination result, and the absolute difference between the two parallel determination results shall not exceed 0.

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1 Method summary

Under acidic conditions, the chloride in the sample reacts with a saturated silver nitrate solution to produce silver chloride precipitation, and the test passes if no turbidity is observed
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The detection sensitivity of this test method is 0.
0003%
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2 Reagents

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1 Nitric acid ;

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2 Anhydrous methanol :

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3 Saturated silver nitrate solution
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3 Apparatus

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1 Sampling cylinder: same as 4.
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3;

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2 Electronic balance: the maximum weighing is not less than 2000g, and the graduation value is 0.
1g
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4 Analysis steps

Add 30 mL of anhydrous methanol to a 100 mL colorimetric tube, and add 6 drops of nitric acid and 18 drops of saturated silver nitrate solution under stirring
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Weigh the mass of the sampling cylinder containing the sample to the nearest 0.
1g
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Connect one end of the connecting line to the outlet valve of the sampling cylinder (note that each joint is well sealed), insert the other end into the colorimetric tube solution, open the outlet valve of the sampling cylinder while stirring, and bubbling injection, the injection volume is about 36g, and the injection time It should be no less than 15min
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Observe whether there is turbidity in the colorimetric tube
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If there is no turbidity in the solution, the test is passed
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Related Links: Industrial Difluorochloromethane (HCFC-22) (2)