8: Soil Colloids (8/11) Flashcards

1
Q

Cation exchange capacity (CEC)

A

Quantifies the capacity of colloids to adsorb cations

Expressed as the number of centimoles of (positive) charge that is adsorbed in the colloid per unit mass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is cmolc?

A

The units of CEC which are expressed as cmolc/kg

1 cmol c = 6.02 x 10^21 charges

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Soil cation capacity

Normal range
What does it depend on?

A

Normal range in soils is 0-180 cmolc/kg

Depends on the total amount of negative sites or negative charges:
- pH of soil matters, it changes CEC
- The relative abundance of different
colloids
- The CEC of those colloids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

4 principles governing CEC reactions

A

Reversibility (cations are not permanently bound)

Concentration of charge (ratio law): chemical equilibrium with soil solution

Cation selectivity

Principle of equivalence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly