Separating Sand and Salt from Water

In the picture

1. 1The beaker of cloudy water holding sand and dissolved salt.
2. 2The wet sand caught in the folded filter paper inside the funnel.
3. 3The clear salty liquid collecting in the conical flask after passing through the filter.
4. 4The evaporating basin heated over the burner, where water leaves as steam.
5. 5The white salt crystals left behind in the cooled second basin.

Examples

• Pouring tea through a strainer so the leaves stay behind.
• Sea salt forming in shallow salt pans as the sun dries the seawater.

Quiz: Separating Sand and Salt from Water (Age 12)

1. 1

   Sand and salt are stirred into water, and the mixture is poured through filter paper. The liquid that passes through looks completely clear. What is in it?

   • Water with the salt still dissolved in it
   • Only pure water, because the paper trapped both the sand and the salt
   • Water with grains of sand that are too small to see
2. 2

   The clear salty liquid is heated until no liquid is left, only white crystals. Why does the salt stay behind while the water goes away?

   • The water turns into steam and escapes, but the salt does not turn into a gas at that temperature
   • The salt turns into a gas too, then cools down and falls back into the basin
   • The heat turns some of the water into new salt, and that is what the crystals are
3. 3

   A glass of water holds chalk powder, which does not dissolve, and sugar, which does dissolve. What is the best way to end up with dry sugar on its own?

   • Filter the mixture to catch the chalk, then heat the liquid until the water has evaporated
   • Heat the mixture until the water is gone, then filter the dry powder that is left
   • Pour the mixture through the filter twice, because the second filter catches the sugar

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.