Water Module: Session 6. Sodium and Yellow Flames

 

Why is there so much sodium in the ocean and so little in fresh water?

 

            Sea water is 3% by weight NaCl which is 0.5 M

 

            Fresh water is 0-1 mM

 

            Lakes in arid regions with no drainage: Dead Sea, Great Salt Lake, Salton Sea

 

 

If sodium accumulates in the ocean, why hasn’t calcium and magnesium that occur in significant concentrations in surface waters? 

 

 

Why are so many salts in the stockroom sodium (or potassium) salts?

 

 

Since most soluble sodium salts have been leached from the soil, why do domestic water supplies often contain significant levels of sodium?

 

            Living close to the ocean (sodium balanced with chloride)

 

What does it mean if you find high sodium but low chloride levels?

 

How is hard water softened?

            Cation exchange - NaCl

            Ion exchange – H+ and OH-

            Soda-lime process – Ca(OH)2 (lime) + Na2CO3 (soda)

 

            Ca+2 (aq) + 2 HCO3- (aq) + Ca(OH)2 (aq) ŕ 2 CaCO3 (s) + 2 H2O

 

What is the difference between atomic emission and atomic absorption?

 

 

 

If the recommended daily allowance of sodium is 2.45 g, how much water containing 300 ppm sodium do you need to drink in order to ingest 2.45 g?