Quicklime and slaked lime

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Quicklime and slaked lime

-When we add water to quicklime it reacts to produce slaked lime (calcium hydroxide), this reaction gives out a lot of heat 

-Word equation;

calcuim oxide CaO + water H2O = calcium hydroxide Ca(OH)2

-Although it's not very soluble, we can dissolve a little calcium hydroxide in more water. After filtering, this produces a colourless solution called lime water

-We can use lime water to test for carbon dioxide. When carbon dioxide is bubbles through clear lime water the solution turns cloudy

-This is because calcium carbonate is formed, which is insoluble in water 

calcium hydroxide Ca(OH)2 + carbon dioxide CO2 -> calcium carbonate CaCO3 + water H2O

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Mortar

-Slaked lime + sand + water = mortar 

-Mortar holds other building materials together 

-It works because the lime in the motar reacts with carbon dioxide in the air, producing calcium carbonate again 

slaked lime Ca(OH)2 + carbon dioxide CO2 -> calcium carbone CaCO3 + water H2O 

-The amount of sand in the mixture is very important, too little sand and the motar shrinks as it dries. Too much sand makes it too weak 

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