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18 Cards in this Set

  • Front
  • Back

Describe the difference between soft water and hard water when reacted with soap

Soft water easily forms lather with soap


Hard water reacts with soap to form scum

Which dissolved ions usually cause hard water?

Calcium ions


Magnesium ions

What are the two types of hard water?

Temporary


Permanent

Explain the differences between temporary hard water and permanent hard water

Temporary can have its hardness removed by boiling


Permanent remains hard even after boiling

Which dissolved ions does temporary hard water contain?

Hydrocarbonate

Give 2 reasons why using hard water costs more money

More soap is needed


Heating temporary hard water produces scale which reduces the efficiency of heating systems

Give 2 health benefits of drinking hard water

Good for the development of bones and teeth


Help reduce heart disease

Give 2 ways permanent hard water can be made soft

By adding sodium carbonate


Using an ion exchange column

Explain how sodium carbonate makes water soft

The soluble carbonate ions precipitate out calcium and magnesium ions to form insoluble carbonates

Explain how an ion exchange column works

Hard water passes through the column


Sodium ions in the column are exchanged for the calcium or magnesium ions in the hard water

Describe how a water filter works

Carbon reduces levels of chlorine, pesticides and other inorganic compounds


Ion exchange resin removes calcium, magnesium, lead, copper and aluminium ions


Silver particles discourage growth of bacteria in the filter

Why is chlorine added to drinking water?

To kill microbes

Give 2 arguments against using chlorine in drinking water

Some people feel it could be a risk to their health


Can react with organic molecules to form toxic compounds

What alternative gas can be used to sterilise swimming pools?

Ozone

Give 3 benefits of adding fluorine to drinking water

Helps reduce tooth decay


No harmful effects


Only tiny amounts added

Give 3 arguments against adding fluorine to drinking water

Can be linked to weakening of bones


People don't have a choice


Safe limits cannot be set

Describe how pure water can be produced by distillation

Impure water sample is boiled and evaporates


Steam is condensed back into a liquid using a condenser


Pure water is collected

What is the main disadvantage of producing pure water by distillation?

Larger amounts of energy needed meaning large costs