3.2 Water Flashcards
What are the two types of water?
Hard and soft
Where is water hard?
Yorkshire, London and South East England
Where is water soft?
Lancashire, North Wales and the Lake District
What does Water hardness depend on?
The mineral ions dissolved into the water from the rocks
What ions make water hard?
Calcium and Magnesium
What are advantages of hard water?
Calcium strengthens bones and teeth
Calcium may also reduce the risk of heart disease
What are the two types of hard water?
Temporary
Permenant
What is temporary hard water?
High concentration of hydrogen carbonate ions
They decompose on heating
What is permanent hard water?
High concentration of sulfate ions
They don’t decompose when heated
What are two methods of removing water hardness if the water is temporary?
Boiling the water
Soap solution
What is created when hard water is heated?
Soft water and scale
Removing calcium, magnesium and hydrogen carbonate ions
What can scale do?
Reduce efficiency in kettles, boilers and pipes
What happens if you add soap solution to soft or hard water?
Soft - Lathers
Hard - Little Lather
What does hard water produce when reacted with soap solution?
Soft water and a precipitate called scum
What are two methods of removing water hardness if the water is permanent?
Adding sodium carbonate
Ion exchange column
What is produced when you add sodium carbonate to hard water?
Soft water
Precipitate of calcium carbonate
Precipitate of Magnesium carbonate
What happens in an ion exchange column?
The resin beads have sodium and hydrogen in them
These ions exchange with the calcium and magnesium producing salt water
Which method of removing water hardness is convenient and cost effective?
Ion exchange
What are the 8 stages of water purification?
Filtering Chlorine added Carbon filter Filtering Flocculation (solution added) Filtering Ion exchange Silver filter
What do the three filters do in water purification?
Removes solids
Removes carbon
Removes precipitate of harmful ions
Why is chlorine added in water purification?
To kill harmful microbes
But not too much as it is toxic
Why is a carbon filter added in water purification?
To remove the chlorine
Why is flocculation (solution added) in water purification?
Removes harmful ions (lead and mercury)
Why is ion exchange used in water purification?
Removes hardness and adjust pH
