1. Experimental steps: dissolving, filtering, evaporating and calculating the yield.

2. The most frequently used instrument is glass rod.

(1) the role of stirring in the process of dissolution, accelerate the dissolution;

② drainage during filtration;

(3) the role of stirring in the evaporation process to prevent uneven heating and liquid splashing;

3. Yield evaluation

① Possible reasons for low yield: liquid spilled or weighed incorrectly during the experiment;

② Possible reasons for high yield: crude salt was not completely purified.