My Sharing Platform => Educational => Chemistry => Topic started by: Mr Smart on September 08, 2014, 10:36:20 AM

Title: Carbonates
Post by: Mr Smart on September 08, 2014, 10:36:20 AM
Carbonates are salts of carbonic acids (H2CO3).  Carbonates are very useful salts, specially calcium carbonate (CaCO3).
 Sources of Calcium Carbonate:  Calcium carbonate can be found in large  amounts in the Peak District. It is found as a type of rocks called limestone  near rivers.
 Forms of Calcium Carbonate:  Limestone is not the only form of calcium  carbonate. Marble and chalk are also other forms of this valuable salt. Chalk  is made of shells of marine algae. Marble on the other hand, is a metaphoric  rock made of limestone at high pressure.
(Ball-and-stick model
 of the carbonate ion, CO32−)
Uses of Calcium Carbonate:  Calcium carbonate has numerous uses. You  have previously studied one of them which is helping in the extraction of iron  from its ore. Another one of these is the manufacture of cement. In this  process, limestone or chalk is mixed with clay and heated in a rotary kiln. The  substance in the mixture react producing cement which is a mixture of calcium  aluminate (Ca(AlO2)2) and calcium silicate (CaSiO3). This is then made into  powder. When it is used, it is sprayed with water make its particles hold  tight.
 Manufacture of Lime: One of the industrial uses of calcium  carbonate is the manufacturing of lime from it. Lime is calcium oxide salt.  This process takes place in a device called lime kiln and it is based on the thermal decomposition of calcium carbonate. Limestone is inserted in the kiln  and heating starts. At the bottom of the kiln air is being blown in. this is  also where lime is collected. The other product of this reaction, carbon dioxide  gas, evolves and escapes at the top of the kiln.
(Carbon Dioxide)
  Uses of Lime: Lime can be used to neutralise soil acidity  in farms. This is because it is a basic oxide. Slaked lime (Calcium hydroxide;  Ca(OH)2) is also a basic oxide can be used as an alternative to lime for neutralising soil acidity. Another use of lime is neutralising sulphur dioxide  waste in power stations. This is because sulphur dioxide is an acidic oxide  while lime is a basic one. This process is called desulphurisation which you  have studied earlier.
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