A sample of rock salt contains sodium chloride, sand and mud. Sodium chloride is soluble in water. Sand and mud are insoluble in water. A student obtains dry crystals of pure sodium chloride from a lump of rock salt. Fig. 1.1 shows some of the steps the student uses. Describe what the student must do after step 3 to obtain dry crystals of pure sodium chloride. ................................................................................................................................................ . ................................................................................................................................................ . ................................................................................................................................................ . ..........................................................................................................................................

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