Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

SFI100 > (#) Soil colloids > Flashcards

(#) Soil colloids Flashcards

1
Q

True or false, soil colloids are the most chemically active portion of the soil

A

True

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

Average soil colloid diameter

A

<1μ or 0.001mm

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

What are the types of soil colloids?

A

Organic
Inorganic

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

What are the types of Organic soil colloids?

A

Humus

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

What are the types of Inorganic soil colloids?

A

Silicate clays
Allophanes
Fe and Al oxides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is Micelle?

A

a silicate clay crystal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Shape of silicate clays

A
  • flaky, laminated, usually hexagonal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Surface area of silicate clays

A

internal and external

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

name a silicate clay crystal

A

Micelle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Name silicate clay’s electro negative charges

A

net negatively charged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Types of Silicate clays

A

1:1 (One silica tetrahedon & one aluminum actahedron)
2:1 Expanding type
2:1 Non-expanding type
2:1:1 or 2:2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

The type of silicate clay that’s one tetrahedral sheet attached to one side of an octahedral sheet

A

1:1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Name a 1:1 silicate clay

A

Kaolinite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

CEC of kaolinite

A

low

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

True or false, kaolinite has high surface area

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

True or false, kaolinite has low water holding capacity

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

True or false, kaolinite has low shrink-swell capacity. Why?

A

True, due to strong hydrogen bonding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Which silicate clay has a symmetrical arrangement of two tetrahedral sheets and a central octahedral sheet?

A

2:1 Expanding silicate clay

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Name a 2:1 expanding silicate clay

A

Montmorillonite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

True or false, montmorillonite has low CEC

A

False

21
Q

Montmorillonite is a major component in what kind of soil?

A

Vertisols

22
Q

What is the D spacing of montmorillonite?

A

10-17A

23
Q

True or false, 2:1 Non-expanding silicate clay has the different composition/structure than 2:1 expanding silicate clay

A

false, they have the same composition/structure, it’s just non-expanding doesn’t expand

24
Q

Why do 2:1 non-expanding silicate clays not expand?

A

presence of K+ ions

25
Q

Name a 2:1 Non-expanding silicate clay

A

muscovite

26
Q

Which silicate clay has two silica tetrahedral sheet and two Mg-dominated octahedral sheet

A

2:1:1 / 2:2 silicate clay

27
Q

Name a 2:2 silicate clay

A

chlorites

28
Q

What are the substitutions in a 2:1 silicate clay’s tetrahedral sheet

A

Al^3+ & Si^4+ (negative charge)

29
Q

What does the octahedral interlayer of a chlorite contain?

A

Mg^2+ & Fe^2+ (positive charge)

30
Q

Hydrous oxide ore are hydrous oxides of Fe and Al commonly dominant in?

A

Highly weathered soils of tropics and subtropics

31
Q

Name hydrous oxides of Fe and Al

A

Gibbsite and Goethite

32
Q

True or false, some hydrous oxides of Fe and Al have definite crystaline structure whilst others are amorphus

A

True

33
Q

True or false, hydrous oxides of Fe and Al are sticky and plastic

A

false, non-sticky and plastic

34
Q

“short-range order minerals”

A

allophanes

35
Q

What soil are allophanes prevalent in?

A

Andisols

36
Q

True or false, Allophanes have low capacity to adsorb cations

A

false

37
Q

Name two allophanes

A

allophanes & imogolite

38
Q

What is humus composed of?

A

C, H, O (non crystaline

39
Q

What are the 3 sources of negative charges?

A

1) Isomorphous substitution
2) Dissociation of exposed OH groups at the broken edges of the mineral
3) Dissociation of functional groups in organic colloids

40
Q

The source of negative charge wherein centrally coordinated cations are replaced by another cation without alteration of crystal structure of the mineral

A

Isomorphous substitution

41
Q

In which silicate clay is isomorphous substitution most prevalent?

A

2:1

42
Q

In which source of negative charge does OH dissociate at a high pH?

A

Dissociation of exposed OH groups at the broken edges of the mineral

43
Q

In which source of negative charge, when at high pH, creates pH dependent negative charge?

A

Dissociation of functional groups in organic colloids

44
Q

The interchange between a cation in solution and another cation on the surface of any surface-active material such as clay or organic matter

A

cation exchange

45
Q

True or false, cation exchange is the result of positive charges in soil colloids, which attract positive ions (cations) from soil solution

A

False, it’s the other way around

46
Q

What is cation exchange capacity (CEC)?

A

sum of exchangeable cations that a soil can adsorb

47
Q

What is base saturation?

A

Proportion of CEC that is made up of exchangeable bases

48
Q

The quantity of a substance that exactly reacts with, or is equal to the combining value of, an arbitrarily fixed quantity of another substance in a particular reaction.

A

Equivalent weight

SFI100 (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions