What happens: Suds form in the water with the washing soda, but
few form in the water with the Epsom salts.
Why: Washing soda “softens” water, while Epsom salts is a mineral
that makes water “hard.”
Tap water often contains calcium salts, which stops soap from making
suds. If water has a lot of salts, it is called “hard.” Washing soda
“softens” or neutralizes the calcium salts in the water and forma a
solid substance, called a precipitate, that falls to the bottom of a
solution when a chemical reaction takes place. (This is where that
ring in the bathtub comes from.
Epsom salts is a mineral that makes water hard. That is why you
couldn't get soapsuds to form. Did your plain tap water make suds? Is
your tap water hard or soft, or in between? Now empty the solutions
in each glass. Do you see any precipitates on the sides of the
containers.?