water hardness

Question 1

how would you identify soft and hard water

Answer 1

when soap is used:
soft = lather
hard = scum

Question 2

what ions in water make them hard

Answer 2

Ca2+ and Mg2+

Question 3

what is temporary hardness caused by and how can it be removed

Answer 3

dissolved calcium or magnesium hydrocarbonate
by boiling in kettle

Question 4

what is permanent hardness cause by

Answer 4

dissolved calcium or magnesium sulfate

Question 5

how can be used in both hardnesses to be softened which causes what to form

Answer 5

sodium carbonate
(washing soda) causing limescale

Question 6

what 2 ions being removed can result in water softness due to carbonate ions reacting with them to make an _____________ precipitate (limescale)

Answer 6

insoluble
Ca2+ and Mg2+

Question 7

both types of hardness can be removed by running the water through ____ _________ _________

Answer 7

ion exchange columns

Question 8

the columns have big resin ___________ with lots of ________ or __________ ions attached which exchange for __________ or ____________ ions in the water. all the ________ ions will be eventually used up so no more _________ ions can be removed

Answer 8

molecules, sodium, hydrogen, calcium, magnesium, sodium, calcium

Question 9

for every Ca2+ ion removed in the water, _____ ions are released from the resin

Answer 9

2 Na+