LISTENING

Why is ocean water salty?

http://dsc.discovery.com/videos/howstuffworks-why-is-ocean-water-salty.html


Listen for the first time and answer the Qs.



 1. What are the desalination plants?
 2. Where does the fresh water come from?
 3. How many per cent of world water are oceans?
 4. Why is sea water salty?
 5. Where is the largest desalination plant in the U.S.?
 6. Where is the polluted water sucked from?
 7. What is the 2^nd stage of the desalination process?
 8. What is reverse osmosis?






Listen for the second time and fill in the missing information.



     1. The quotation at the beginning reads as follows.

         “Water, water ……….., and not a ……….to drink.”

          (S.T. Coleridge, the Ancient Mariner)


     2. Rock particles which get into the sea water are minerals like chloride, ……….,

          sodium, and ………………..



    3. The Sun´ s heat …………..fresh water through …………..



    4. Every day, ……… of gallons of water from powerplants are sucked.



     5. This water is used in powerplants for ……………….


6.      When they add chemicals to the water, larger particles………………………..


     7.   The pressure exerted in reverse osmosis is ………..pounds per …………………..


8.   The membrane pores used in reverse osmosis are a) thicker than human hair

                                                                                           b)
thinner than human hair