Method for measuring impurities in solid alkali

　　After the formation of solid alkali,there will be a small amount of residue.If the residue does not come out,it will endanger its purity and disrupt its reaction with other chemicals.
　　2.Accurately weigh 1.5-2.0 grams of sample in a 250 milliliter measuring cup on an analytical balance,and release water without melting carbon dioxide.
　　3.Transfer the quantitative analysis of solid alkali to a 250ml volumetric flask,dilute tap water to the mark and shake.
　　4.Inhale 25.00 mL(3 portions)of the test solution into a 250 mL conical flask,add a few drops of phenolphthalein indicator,and use 0.1 mmol/L standard solution drops to change the aqueous solution from bright red to white.No color.Record the volume V1 of hydrochloric acid standard sample at the terminal,and then record 2 drops of methyl orange indicator.
　　5.Titrate the test tube again with hydrochloric acid standard solution until the aqueous solution changes from light yellow to orange,which is the endpoint.
　　6.Record the V2 consumption of hydrochloric acid standard solution.
　　That concludes today's content.There may be a small amount of residue in solid alkali,which is normal,but excessive residue can damage its quality.Everyone can measure using this method and accurately calculate the moisture content of the residue.