WLW Day # 4: Water as Solvent

Science Experiment # 3: Water as Solvent

Materials needed:

* chalk
* filter paper
* heat source
* lime powder or tablets
* phenolphthalein
* 2 pyrex beakers




Instructions:

* Crush some chalk
* Mix chalk into water in a beaker

* Pour the mixture through filter paper. The water appears to be "pure".
* Boil the water or let it evaporate away.

Q: What is left?

* In a beaker, mix lime powder or tablets and water.
* Filter until clear.
* Fill another container with water.
* Obtain some phenolpthalein (Hln or phph) and add a few drops to a glass of "pure" water.
* Add a few drops to the water mixed with lime.

  Q: What are the results?
  Q Relate to hydroponic gardening (growing plants in water instead of soil)?

What we learned:

* Water's power to dissolve substances (e.g. chalk + water)
* Substances can be transported when dissolved in water  (e.g. chalk + water or line + water)
* Water can carry out chemical reactions (e.g. lime+water+Hln)
* A clear water does not always mean "pure" water. It may carry substances or minerals.
* Application: Water passing through soil dissolves some of the minerals and transports them through the soil to plants and animals, and contributes to the salinity of the sea.