Expert: Leo Carr - 5/16/2006

Question
I'm in Year 8 and I would like to know -
What is simplest and best way to separate a mixture of salt, sand and iron filings and retain all?
You don't have to give a direct answer but more or less an idea of how the best way is.

Answer
First determine what the mixture components are soluble in.   For example you know that salt is soluble in water, so you can dissovle it some water. Since sand is insoluble in water, you can filter it. The sand will be in the filter paper the salt will have filtered since it is dissolved.  

The iron is still in the filter paper, iron will dissolve somewhat in acid.  A few drops of acid will confirm you have iron.  Or you can just conclude that since its in the filter paper.  Now take your filtrate, (the water with the dissolved salt) and heat it gently, the water will evaporate off and the salt should recrystalize.

Hope this helps.