Solvay Process

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Solvay process

Raw materials
-NaCl, salt
-CaCO3, limestone
-H2O, water
-NH3, ammonia is recycled

Useful products
-sodium carbonate. Na2CO3 – reason for process

Waste products
-CaCl2, calcium chloride

Chemical properties of the main product (Na2CO3)
-Forms several hydrates which are used in many ways
-It is moderately alkaline, so it can neutralise strong acids -Can precipitate many metal ions from solution as carbonates

Uses of sodium carbonate
-Glass manufacturing (most common use)
oUsed as a flux gas which lowers the melting point of the silicon dioxide and the calcium carbonate -Soap and detergents
oUsed as a base in soap and detergents. It is also used to make sodium phosphate and sodium silicate that act as builders -Softening hard water
oThe carbonate ions precipitate calcium and magnesium ions, this is why it is used in some soaps and detergents -Baking soda production
oSodium hydrogen carbonate or bicarbonate of soda is produced as a part of the process. oThe sodium carbonate is dissolved to make a concentrated solution and a stream of CO2 is passed through it so that sodium hydrogen carbonate crystals form from the solution oSodium hydrogen carbonate = baking soda, used as rising agent in cooking

Stages of this product + Equations
1.Production and purification of brine
oBrine is put in shallow ponds where the water is evaporated leaving salt oCalcium and magnesium are removed from the salt collected, calcium is precipitated by sodium carbonate and the magnesium is precipitated by sodium hydroxide oCa2+(aq) + CO32–(aq) CaCO3(s)

oMg2+(aq) + 2OH–(aq) Mg(OH)2(s)
oA flocculant is added and the precipitate removed, the brine is then concentrated so that it is saturated.

2.Hydrogen carbonate formation
i.Calcium carbonate from limestone is heated to form carbon dioxide and calcium monoxide, coke is also in the kiln. Calcium oxide is...
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