Soil contains organic matter called humus. Humus is classified into humic and nonhumic materials. Humic materials are operationally divided into three main fractions:
Humic acid, fulvic acid, and humin.

Properties of Humic Materials.
Features Humic Acid Fulvic Acid Humin
Solubility in water soluble in alkaline pHs soluble at all pHs insoluble at all pHs
Aromatic content highly aromatic highly aromatic highly aromatic
Carboxylic acid content some high low
Phenolic content some some some

Humic materials
↓ HCl
soluble insoluble
↓ ↓NaOH
Fraction A soluble insoluble
↓ ↓
Fraction B Fraction C

In flowchart above, Fraction B is most likely:

a) Humic acid. b) Fulvic acid. c) Humin.

m=9

step-by-step explanation:

when 25.0 ml of 0.700 mol/l naoh was mixed in a calorimeter with 25.0 ml of 0.700 mol/l hcl, both initially at 20.0 °c, the temperature increased to 22.1 °c. the heat capacity of the calorimeter is 279 j/°c.

the equation for the reaction is:

naoh + hcl → nacl + h₂o

moles of hcl = 0.0250 l hcl ×

0.700

mol hcl

1 l hcl = 0.0175 mol hcl

volume of solution = (25.0 + 25.0) ml = 50.0 ml

mass of solution = 50.0 ml soln ×

1.00

ml soln

= 50.0 g soln

δt=t2-t1

= (22.1 – 20.0) °c = 2.1 °c

the heats involved are

heat from neutralization + heat to warm solution + heat to warm calorimeter = 0

q1+q2+q3=0

nδh+mcδt+cδt=0

0.0175 mol ×

δh

+ 50.0 g × 4.184 j·g⁻¹°c⁻¹ × 2.1 °c + 279 j°c⁻¹ × 2.1 °c = 0

0.0175 mol ×

δh

+ 439.32 j + 585.9 j = 0

0.0175 mol ×

δh

= -1025.22 j

δh=1025.22j0.0175 mol= -58 600 j/mol = -58.6 kj/mol