(seven 0 1 seven? Rizhao) It is known that the raw salt sample contains impurities such as Na _ 7 SO _ 4, 8gCl _ 7 and CaCl _ 7. The laboratory purification process is as follows: (1) Use trays.

(She) is "right-handed" in weighing materials, so when weighing raw salt with tray balance, if the pointer is to the right, it means that the left tray is light and heavy;

(2) excessive sodium hydroxide solution is added to remove magnesium chloride, and the chemical equation of reaction P is mg tal2+2 NaOH = mg (OH) 2 ↓+2 natal;

(3) adding excessive P sodium carbonate solution P mesh P to remove impurity βL2, and adding excessive P reagent EA β L2;

(4) a method for separate insoluble solid and soluble solid P by filtration, step 6, that name of the operation ap is filtration, and in this step, the end of the glass rod P gently leans against one side of the three-layer filt paper P;

(5) In the operation of step 7, enough hydrochloric acid P is added dropwise to the filtrate, and the added excessive reagents NaOH and Na2TAO3 are removed.

(6) The role of glass rod P in evaporation and crystallization process: to prevent droplets from splashing due to excessive local temperature during evaporation.

So, the answer is: (she) D;

(2)Mg betal 2+2 NaOH = Mg(OH)2↓+2 natal；

(3) removing impurity βL2, and adding P excess reagent etal2.

(4) filtering; Three-layer filter paper;

(5) NaOH and Na2TAO3 added with excessive reagent p are removed.

(6) To prevent droplets from splashing due to excessive local temperature during evaporation.