Kaolinite has the smallest CEC of all clay minerals in Table 6.5. How would you investigate whether permanent or variable charges dominate in kaolinite? MineralSmectiteIlliteKaoliniteChloriteVermiculiteTable 6.5 Cation-exchange capacity of minerals and humusbcec/mol kg-1MineralGoethiteGibbsiteHematiteAllophaneImogoliteHumus1.000.300.070.301.50-1Note: The unit cmol hg is sometimes used:1 mol/kg = 1 mmol/g = (100 cmol)/(10 hg) = 10 cmol/hg.-bcec/mol kg-10.100.050.050.700.702.00

Answered: Kaolinite has the smallest CEC of all…

Applications and Investigations in Earth Science (9th Edition)

9th Edition

ISBN:9780134746241

Author:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa

Publisher:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa

Chapter1: The Study Of Minerals

Section: Chapter Questions

Problem 1LR

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Question

Kaolinite has the smallest CEC of all clay minerals in Table 6.5. How would you investigate whether permanent or variable charges dominate in kaolinite?

Mineral
Smectite
Illite
Kaolinite
Chlorite
Vermiculite
Table 6.5 Cation-exchange capacity of minerals and humus
bcec/mol kg-1
Mineral
Goethite
Gibbsite
Hematite
Allophane
Imogolite
Humus
1.00
0.30
0.07
0.30
1.50
-1
Note: The unit cmol hg is sometimes used:
1 mol/kg = 1 mmol/g = (100 cmol)/(10 hg) = 10 cmol/hg.
-
bcec/mol kg-1
0.10
0.05
0.05
0.70
0.70
2.00

Expert Solution

Step 1 Answer

CEC is the cation exchange capacity.

How this phenomenon occurs, generally the clay minerals and the organic matter tend to be negatively charged, hence they will try to attract positively charged ions on their surfaces by forces like electrostatic.

So the total no of cation a soil can hold is called as the soils cation exchange capacity.

The cation exchange capacity depends on several factor of the clay, that is the P^H of the soil, the grain size of the soil.

The kaolinite have very low CEC because it's grain size is much large thus it gives higher surface area per unit weight.