Flashcards in Water Deck (19):
how do we tell if water is soft or hard?
soft water will produce a lather if mixed with soap.
what does hard water contain?
magnesium and calcium compounds, dissolved in the water.
magnesium and calcium ions make the water what?
scum is an insoluble precipitate made how?
with hard water and soap.
washing powder will make what happen from hard water?
make scum stick to clothes.
benifits of hard water is
- bone development
- teeth development
- reduction in heart disease
what is the difference between temporary hard water and permanent hard water?
temporary - can be softened by heating
permanent - remains hard even after being boiled or heated.
how can we use washing soda to soften water.
use sodium carbonate(washing soda) to produce CaCO3 + Na
ion exchange columns use sodium to do what?
the sodium or hydrogen is exchanged in the resin with calcium or the magnesium.
hard water contains hydrogencarbonate ions.
hydrogencarbonate ions decompose to form carbonate ions, they then react to magnesium or calcium
scale is also known as what?
screens in purifying water does what?
remove debris in the water.
settlement tanks do what?
sand and soil settle out at the bottom of this container.
coagulation does what?
aluminium sulfate makes particles of dirt stick together and settle
filter bed does what?
filters very fine sand and insoluble solid particles
chlorine is added at the end to do what?
flourine is some areas for whatm
what are the arguments for and against adding flourine to water?
- Reduces tooth decay
- only in tiny amounts
- possible links with learning difficulties