What is cation exchange capacity?

Cation Exchange in Soil?

• 1. compare the cation exchange capacity of a kaolinitic soil and montmorillonitic soil. 2. when the soils in Part 2 were leached with 0.2N KCI solution, calcium was found in the leachate, when leached with water, none or only small amount was found. explain why. 3. explain the relation between the amount of negative charge in the soil and its ability to filter contaminated water. 4. Explain the much higher mobility of nitrate ( NO3-) than calcium (Ca2+) in soils. Note: Part 2: DATA results" Test tube containing____Relative amount precipitate BaCr2O2____relative cation exchange capacity --------------------------------------… BaCl2 Sol'n HIGH None Filtrate,Soil No.1 LOW high Filtrate, Soil No.2 Medium Low

• Answer:

  1. kaolinite is a 1:1 clay with very little - charge, and mont. is a 2:1 with a very high - charge. 2. the Ca will form a stronger bond with Cl so it knocks off K and K stays with the clay 3. more charge sites = more bonding sites 4. NO3- can volatize and doesn't have much of anything it can bond too where Ca2+ does