Wednesday 25 January 2012

An explanation about separating rocksalt

Tom’s Big Write
If you want to separate rock salt (salt and sand) you first need to add water as this will dissolve the salt. Then the brown sloppy mixture can be filtered with a funnel and filter paper. Put a funnel into a jug and then put filter paper in the funnel. Carefully pour the mixture into the filter paper. Allow the watery mixture to seep through the filter. The mixture will separate into saltwater and sand. Leave the sand to dry.

Then you have to take a pan, fill it with the saltwater and boil it. This will separate the salt and the water by turning the water into vapour because if a liquid gets hot enough it evaporates, turning it into vapour. To collect the vapour you can take a tray that has been in the freezer and hold it over the pan upside down. The cold will condense the steam back into water, turning it from a gas into a liquid. After a minute the tray will feel wet.

If you check the pan, there should be a white substance at the bottom. That is salt. Overall the sand and salt successfully separate.

Dissolve               turns into part of the liquid
Vapour                 gas/steam
Evaporate           turns a liquid into a gas
Condense           turns gas into liquid

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