Water Flashcards
What can cause calcium and magnesium ions to get into water?
The water having flowed through rocks which contained magnesium sulphate calcium sulphate four example limestone and chalk.
What makes water hard?
Calcium ions and magnesium ions.
C a T.
Mag 2.
What does hard water form when heated?
Scale.
What sort of water makes a better lather of soap?
Soft
What are the benefits of hard water?
It’s good for bones and teeth
People are less likely to have heart disease
What are the two types of hard water?
Temporary and permanent
What causes temporary hardness?
The Hydrogen carbonate ion
HCO3 minus
What causes permanent hardness?
Dissolved calcium Sulfate
How do you remove temporary hardness?
Boilin
Or washing soda
Or ion exchange columns
How does boiling remove temporary hardness?
It decomposes the calcium hydrogen carbonate and makes calcium carbonate, water and CO2
Does boiling get rid of permanent hardness?
No
What types of hardness can washing soda soften?
Both temporary and permanent.
What softens permanently hard water?
Ion exchange columns and washing soda
What is washing soda called?
Sodium carbonate
What is the formula for sodium carbonate?
Na2CO3
How does washing soda soften permanent hardness?
The added carbonate ions react with the ions and make a precipitate of either magnesium or calcium carbonates.
They’re no longer dissolved and don’t make it hard.
What is produced when permanently hard water has soda added to it?
CaCO3
What type of hardness is removed by ion exchange columns?
Both temporary and permanent.
How does an ion exchange column work?
The columns have lots of sodium ions which are ‘exchanged’ with the calcium and magnesium ions.
Give a method of comparing the hardness of water.
Titration
What is put in the Burette in the titration of water samples?
Soap solution.
What are the processes in water treatment?
Screens- mesh screen
Sedimentation- sticking pieces together
Filtering through gravel beds
Chlorination
What can people buy to make their water cleaner?
They can buy carbon or silver filter.
What does a carbon filter remove?
The chlorine taste.
What does silver filters remove?
They kill bugs
How can you make pure water?
Distillation
What is distillation?
Boiling water to make steam and condensing it.
Why don’t we condense most water?
Because it is expensive
What are the advantages of adding Fluorine to water?
It helps reduce tooth decay.
What are the problems with adding fluorine to water?
It can cause cancer and vibe problems
It needs to be constantly monitored
Mass medication
Why is chlorine added to drinking water?
It prevents disease.
What are the problems with chlorine in water supplies?
It can react with other substances and create toxins
Some studies link it to cancers
