C3 Part 1

Kayleigh Peek
Mind Map by , created over 5 years ago

AQA Further Additional Science C3 Part 1 - Water

Kayleigh Peek
Created by Kayleigh Peek over 5 years ago
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C3 Part 1
1.1 Hard Water or Soft Water?
1.1.1 Hard water is water that contains a lot of dissolved compounds, usually Calcium and Magnesium
1.1.2 Water becomes hard when it flows through chalk or limestone rock
1.1.3 What happens to rainwater? 1) Rain water reacts with Carbon Dioxide in the air to form Carbonic Acid (slightly acidic rainwater) 2) If the Slightly acidic water runs through a city with a high amount of limestone, it reacts to form Calcium Hydrogen Carbonate, which is dissolved in water to form hard water
1.1.4 The more Ca2+ ions present in the water, the harder it is
1.1.5 The harder the water, the more drops of soap solution (Wanklyns) is needed to form a lather
1.1.6 Permanents hard water remains hard when boiled
1.1.7 Temporary hard water is softened when boiled
1.2 Making hard water soft
1.2.1 To soften hard water you need to remove the dissolved Calcium and Magnesium ions which make the water hard Boiling By boiling the temporary hard water you cause the Hydrogen Carbonate ions to breakdown into Hydrogen and Carbonate ions. The carbonate ions that are formed react with the Calcium or Magnesium ions, forming either Calcium Carbonate or Magnesium Carbonate which are precipitates Adding Sodium Carbonate By adding Sodium Carbonate to the temporary hard water, we are in effect adding Carbonate ions to the water. The carbonate ions react with the Calcium ions (which are making the water hard in the first place) to form Calcium Carbonate which is a precipitate Ion exchange columns
1.3 Water for life
1.3.1 Untreated water Microbes cause diseases such as Cholera and Tetanus and can cause health problems Chemicals that make the water smell, make the water unpleasant to drink Solid things (i.e insects or toilet paper) block pipes and taps and may carry microbes Salts, such as nitrates, cause diseases such as Cholera and Tetanus
1.3.2 Treating water Microstainers Large rotating sieves which remove solids including algae Sand Filters Football pitch sized beds of sands, and 1m deep, as water trickles through solids and harmful bacteria are removed Chlorine is added to kill bacteria Ozone kills bacteria and destroys pesticides
1.4 Fluorides and filters
1.4.1 Carbon Filter Removes chlorine from water and compounds with bad tastes and smells Contains activated carbon. Has tiny holes to increase surface area. Unwanted substances stick to the Carbon (ADSORPTION)
1.4.2 Silver Filter Ions destroy bacteria Catalytic action of silver ions with oxygen provides a sanitiser which means we don't have to use as much chlorine
1.4.3 Ion Exchange resin Lead, Copper or Cadmium ions are removed They replace some dissolved substances in water to improve taste and quality
1.4.4 FOR 1 part/million Protect us from tooth decay or heart disease
1.4.5 AGAINST Ethically wrong Cant set safe limits of fluoride so people may take more than is safe Excess fluoride affects the brain and has been associated with Alzheimar's disease in old people

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