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6
The molar concentration of the soda equivalent and its titer is calculated by
the equation:
Report on laboratory work must be handed over to the teacher.
LESSON 3.
BUFFER SOLUTIONS. BUFFERY CAPACITY
Required base level.
Solutions, the molar concentration (molarity) of solutions. Strong and weak
electrolytes. Equations of neutralization, pH of solutions of acids and bases.
Questions for the preparation for the lesson.
1. Buffer solutions, classification of buffer systems.
2. The mechanism of action of buffer solutions, the equation of reactions of
buffer action. Zone of buffer action.
3. The Henderson-Hasselbach equations for calculating the pH of solutions
of various types.
4. Buffer capacity and its dependence on various factors.
5. Buffer systems of the body and their brief characteristics.
Homework exercises.
1.Write the equations of reactions that take place when adding: a) a strong
acid; b) alkalis. Calculate the ratio of components of the hydrocarbonate buffer
system of blood. (pK
a
(H
2
CO
3
) = 6.1).
2. Determine the pH of the phosphate buffer system if 20 ml of 0.01 M
sodium hydrogen phosphate solution and 30 ml of a 0.02 M sodium dihydrogen
phosphate solution were used for its preparation. K
a
(H
2
PO
4
–
) = 6.2×10
–8.
Write
the equations of reactions that occur when added to the buffer system: a) KOH;
b) HNO
3.
3. Determine the pH of the acetate buffer system containing 0.2 mol/l
CH
3
COOH and 0.2 mol/l CH
3
COONa. How will the pH value change when
added to 1 liter of this mixture: a) 0.1 mol/l HCl; b) 0.1 mol/l NaOH? How
2
3
2
3
(Na CO )
(Na CO )
1000
eq
eq
C M
T
⋅
=
3
.
3
2 3
2 3
(HNO )
(H NO )
(Na CO )
(Na CO )
eq
ar
eq
a
С
V
C
V
⋅
=