Thursday 16 February 2017

TOPIC 2:HARDNESS OF WATER

                                          HARDNESS OF WATER

                                           
                                                 
                       WATER
            Is a colourless compound of hydrogen and oxygen elements chemically combined together.
water contains dissolved minerals this make water to become hard.
     
                                           TYPES OF WATER
There are two types of water depending on dissolved  minerals or compound,these are;

  1. hard water
  2. soft water              
                                      1:HARD WATER

Is the one that does not readily form lather with soap,due some dissolved substances such as Ca and Mg ions.
                                     2:SOFT WATER

Is the one which lathers readily with soap.or is water which has low concentration of calcium carbonate and other ions.

                                   CAUSES OF HARDNESS OF WATER
Water is said to be hard if it contain calcium and magnesium ions of their dissolved salts.these Calcium and magnesium salts are;
                     calcium sulphate(CaSO4)
                     Magnesium chloride(MgCl)
                     magnesium sulphate(MgSO4)
                   
                                    TYPES OF HARDNESS OF WATER
There are two types of hardness of water,which are;
             
             1:temporary hardness of water(temporary hard water)
             2.Permanent hardness of water(permanent hard water)


    1:TEMPORARY HARD WATER

Is the water that can be softened by boiling or adding lime .Temporary hard water contains hydrogencarbonates of calcium and magnesium.

      Ca(HCO3)2→H2O +CO2+CaCO3

    METHORDS  OF REMOVING TEMPORARY HARDNESS OF WATER


  • By boiling               Ca(HCO3)2→CaCO3 + H2O + CO2
  • Adding slaked lime(Ca(OH)2                   Ca(HCO3)2 + Ca(OH)2→ CaCO3 + H2O + CO2
  • Adding washing soda (Na2CO3) 

       .distillation                                                                                                                                                                                                                                                                                                                                     2:PERMANENT HARD WATER

Is water that can not be soften by boiling.

             CAUSES OF PERMANENT HARDNESS OF WATER
Is caused by presence  of sulphate ions () and chlorides ions of calcium and magnesium.
       →these compounds of calcium and magnesium are:
                         magnesium suphate
                         magnesium chloride
                         calcium sulphate
                        calcium chloride

         METHORDS OF REMOVING PERMANENT HARD WATER
  • Distillation
  • by permutit process(ion exchange process)
  • by adding washing soda
  • using synthetic ions                                                                                                                                                                                                                                                                                                                     ADVANTAGES OF HARD WATER
  • Has good taste due to dissolved minerals 
  • helps for formation of bones and teeth eg;calcium
  • helps in formation of strong shells of aquatic organisms
  • Helps to prevent corrosion in water pipes
  • hard water is generally safer for drink more than soft water
  • hard water does not dissolve lead(Pb),as the result it does not cause lead poisoning when lead is used in transferring the water into households.                                                                                                                                                                                                                                                                                                                                                                                                                                     DISADVANTAGES OF HARD WATER
  • It waste soap during washing clothes
  • It wastes fuels in boilers
  • it cause formation of scum on clothes and utensils
  • It causes limescale in water boilers,kettles and water pipes
  • wastes time during washing clothes
  • elimika

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