water (further) Flashcards
How do we purify water?
filtration and adding chlorine
Why do we filter water?
remove all solids
Why do we add chlorine to water?
kill bacteria
Why is fluoride added to water?
to improve teeth
Why is adding fluoride not accepted by some people?
they haven’t been given a choice
When can dirty water become a large problem?
3rd world countries
How does calcium and magnesium get into water?
dissolves from washing over rocks
What does calcium and magnesium make water?
hard
What is scum?
insoluble black solid formed when hard water reacts with soap
What is scale?
calcium/magnesium carbonate, insoluble
How is hard water good for our health?
good for teeth and bones and for preventing heart disease
What is a disadvantage of hard water?
difficult to make lather
How can we test for hardness?
measuring how much froth comes from adding soap and shaking, the higher the froth the softer the water
How does an ion exchange column soften water?
replaces sodium ions for Mg/Ca ions
What does adding sodium carbonate do to hard water?
softens it, Ca and Mg form precipitates
