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Acids and bases

Metal oxide and metal hydroxide are bases some are soluble in water are called alkalis
Eg sodium hydroxide and calcium hydroxide
Neutralisation takes place when an acid and a base react to make salt and water
Acid+base-salt+water
Indicators show a sudden colour change at one pH
Universal indicator shows a gradual range of colour change as it contains a mixture of different indicators
In a solution all acids contain h+ ions (hydrogen)
Alkalis contain OH ions (hydroxide ions)
Neutralisation involves H+ + OH- = H2O

Salt acid react with a base and metal carbonates to form salt
Acid +base -salt+water acid + metal carbonate - salt +water + carbon dioxide

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Chemicals from the sea

Sodium hydroxide and chlorine are used to make household bleach
Chlorine and sodium hydroxide are important raw materials they are involved in making about half the chemicals we use on a daily basis including solvents plastics soap medicines and food additives
Sodium chloride solution brine can be separated by electrolysis
Hydrogen is made at the negative cathode chlorine is made at the positive anode
Sodium hydroxide forms in a solution

Salt is mined in Cheshire in two ways
Mining it from the ground as rock salt
Solution mining by pumping in water and extracting saturated salt solution
Mining salt can lead to subsidence the ground above a mine can sink causing landslips and destroying homes
Salt at the surface particularly brine solution can escape and effect habitats

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