1. Required instruments: 1 1000ml brown volumetric flask, 1 100ml brown drop bottle, 1 100ml beaker, 1 25ml brown burette, 1 10ml fat belly pipette, 1 suction ball; 100ml acetone solution, 1000ml distilled water.
2. Reagent preparation: (stored in a brown glass bottle, pay attention to avoid heat and light);
①Indicator: Dissolve a whole bottle of sample A (red) reagent with 100 ml of acetone, transfer it into a 100 ml brown dropper bottle, protect from light, and store it in an airtight place for use;
②Test reagent: Dissolve a whole bottle of sample B (white) reagent with about 100 ml of distilled water, transfer it all into a 1000 ml brown-brown volumetric flask, add distilled water to make up to 1000 ml, shake well, store it in a dark place and keep it closed use.
3. Operation steps:
1) Use a 10ml pipette to accurately draw 10ml of the solution to be tested into a 100ml conical flask, drop 5 drops of indicator, and shake well (yellow);
2) Use a pipette to inhale 10ml of the test agent for titration; during titration, shake well while dripping, and observe the change of the color of the solution, until the solution changes from yellow to light red as the end point, read the consumption of the dripped test agent V (ml);
3) Calculation of results: the concentration of this product (‰) ≈ 0.4 x V (for example: if the consumption of the test agent is 0.5 ml, the concentration of the dressing agent in the solution to be tested is 0.2‰, that is, 0.2 per thousand).