C3.2 Water Flashcards
Why is hard water good?
Tastes better
Good for teeth and bones
Reduces heart disease
What ions are in hard water?
Ca or Mg
Why can hard water increase cost?
More soap is needed for a lather
What is soap?
Sodium stearate
What’s the equation for soap and hard water?
Sodium stearate + calcium ions = sodium ions + calcium stearate
What kind of reaction is soap and hard water?
Precipitation reaction
What is scum?
Soap and hard water (calcium stearate)
Chemical formula for stearate?
C17H35CO2
Rain water + carbon dioxide (in rocks) = ?
Carbonic acid H2CO3
What’s carbonic acid+calcium carbonate (in rocks)?
Calcium and hydrogen carbonate
What’s in temporary hard water?
Hydrogen carbonate HCO3
Calcium+ hydrogen carbonate with heat= ?
Calcium carbonate and water and carbon dioxide
What’s scale?
When temporary hard water is heated calcium carbonate is made which when heated makes scale
Why does scale make a kettle inefficient?
Sticks to the side and coats the heating element so more energy is needed
How can you make hard water soft?
Add washing soda Na2CO3
Ion exchange with Na and H ( but Na is salt so is unhealthy)
Distillation
Where has soft water?
Leeds
Manchester ( ish)
Wales
Where has hard water?
Lincoln
London
Bristol
Southampton
Explain water treatment?
Reservoir Metal bars Sedimentation tank so soil and sand sink Aluminium sulphate and line added so dirt clumps together Sand bed for filter Chlorine added to kill bacteria pH checked and stored
What do white beads do in a water filter cartridge?
Ion exchange resin
What do black beads do in a water filter cartridge?
It’s charcoal or carbon and it binds to chlorine or small molecules
What do silver particles do in a water filter cartridge?
Kill microorganisms
Give 3 advantages of fluoridation?
Helps dental care
Some can’t afford toothpaste
Saves NHS money from dental care
3 disadvantages of fluoridation?
Can’t decide for others
Linked to learning disabilities
Only a small difference
