1. ANALYTICAL CHEMISTRY Volumetric Analysis Chapter 4 Dr. salwa albohy
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2. Volumetric Analysis
Volumetric Analysis : depends on interaction of substances in solution in the ratio of their equivalent weights . Volumetric analysis involves using volumes of liquids to analyse a concentration
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3. Volumetric Analysis
concentration -What equation do we know involving
n = Cv
-Concentration is expressed in mol L-1, which is given the symbol M (C).
To do this we need the following things:
I.A chemical of a known concentration that will react with our ‘unknown’ concentration chemical
II. An indicator that will tell us when all the chemical has been reacted
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4. I- Ionic combination reactions:-
Volumetric analysis
To understand volumetric analysis, we must understand the types of reaction that
happen in it.
Types of reactions used in volumetric analysis :
I- Ionic combination reactions:-
- The reaction goes to completion due to formation of slightly ionizable or slightly
insoluble products.
a- Neutralization reaction :
In which acid reacts with base to form slightly ionized water.
H+ + OH H2O
b- Formation of precipitate :
Ag+ + Cl AgCl 
c- Formation of slightly ionizable complex :
Ag+ + 2 CN [Ag(CN)2]-
Ca+2 + H2Y-2 [EDTA] H+ + CaY-2 [Ca-EDTA complex]
II- Electron transfer reactions :
In which electron transfer from one reactant to another. It is called
(oxidation -reduction reactions)
Ce+4 + Fe Ce+3 + Fe+3
i.e. Fe Fe+3 + e oxidation (loss of es.)
Ce+4 + e Ce reduction (gain of es)

5. Volumetric Analysis Classification of Volumetric Methods
1. Acid-base titrations.
2. Precipitation titrations.
3. Complexometric titrations.
4. Reduction-oxidation (Redox) titrations
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6. Equivalence point – the point at which the reaction is complete
Titrations
In a titration a solution of accurately known concentration is added gradually added to another solution of unknown concentration until the chemical reaction between the two solutions is complete.مهم
Equivalence point – the point at which the reaction is complete
Indicator – substance that changes color as the pH of a solution changes (or near) the equivalence point
Slowly add base
to unknown acid
UNTIL
the indicator
changes color
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7. Acids and Bases
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8. Acid–Base Learning Objectives
To know that solutions can be sorted by whether they are: acid, Base or neutral.
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9. Acid Properties sour taste
change the color of litmus from blue to red.
react with
* metals such as zinc and magnesium to produce hydrogen gas
* bases to produce water and an ionic compound (salt)
* carbonates to produce carbon dioxide. ..
These properties are due to the release of hydrogen ions, H+, into water solution.
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10. Acids
There are many acids present in our everyday lives.
Lemon juice contains citric acid, and vinegar contains acetic acid.
Some strong acids are hydrochloric acid, sulphuric acid and nitric acid.
Some weak acids are ethanoic acid, citric acid and carbonic acid.
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11. Base Properties *bitter or caustic taste * a slippery, soapy feeling.
* the ability to interact with acids
* the ability to change litmus red to blue
These properties are due to the release of hydroxide ions, OH-, into water solution.
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12. Bases Bases are present in many cleaning substances
in use in our homes
Kitchen cleaners are alkaline because
they contain ammonia or sodium hydroxide, which attack grease.
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13. Acid-Base
Acid- base theories
1- Arrhenius theory :-
Acid : Is the substance which ionize to give H eg. HCl
Base : Is the substance which ionize to give OH eg NaOH
2- Bronsted - Lowry theory :-
Acid : Is the substance which donate proton.
Base : Is the substance which accept proton.
Every acid has a conjugate base and the base has conjugate acid.
The stronger the acid the weaker its conjugate base and vice versa.
Eg. HCl H2O Cl H3O+
Acid base conj.base conj.acid
Eg. NH H2O NH OH-
base acid conj.acid conj.base
N.B Water behave as acid or base because it is neutral.

14. 3- Lewis theory :-
Acid : Is substance which accept lone pair of electrons eg. BF3, AlCl3.
Base : Is substance which donate lone pair of electrons eg NH3, amines.

15. 1.Arrhenius acid and base
Arrhenius acid is a substance that produces H+ (H3O+) in water
Arrhenius base is a substance that produces OH- in water
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16. Hydronium ion, hydrated proton, H3O+
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17. 2. Brønsted acid and base A Brønsted acid is a proton donor
A Brønsted base is a proton acceptor
base
acid
acid
base
A Brønsted acid must contain at least one
ionizable proton!
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18. Brønsted acid and base Ammonia acts as a weak Brønsted base
( proton acceptor) and
water acts as an acid (proton donor)
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19. Brønsted acid and base Water acts as a weak Brønsted base
( proton acceptor) and
HCl acts as an acid (proton donor)
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20. Brønsted acid and base Water acts as an base or as acid
depends on the other species present.
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21. Brønsted acid and base
Identify each of the following species as a Brønsted acid, base, or both. (a) HI, (b) CH3COO-, (c) H2PO4-
HI (aq) H+ (aq) + I- (aq)
Brønsted acid
CH3COO- (aq) + H+ (aq) CH3COOH (aq)
Brønsted base
H2PO4- (aq) H+ (aq) + HPO42- (aq)
Brønsted acid
H2PO4- (aq) + H+ (aq) H3PO4 (aq)
Brønsted base
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22. Acids and Bases
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23. Acid–Base reactions Acid–Base reactions = Neutralization reactions
acid + base salt + water
HCl (aq) + NaOH (aq) NaCl (aq) + H2O
H+ + Cl- + Na+ + OH Na+ + Cl- + H2O
H+ + OH H2O
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24. Acid-Base Titrations
An acid-base titration can be used to determine the concentration of an acid or base solution
titration:
a technique for determining the concentration of an unknown solution using a
standard solution
a solution with a known concentration
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25. Acid-Base Titrations
The equivalence point in a titration can be determined using either a pH indicator (ex. Phenolphthalein ph.ph) or a pH meter.
Equivalence point:
the point in the titration where stoichiometrically equivalent amounts of base have been added to the acid (or vice versa)
the base added has completely reacted with all available protons (H+)
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26. Region of high buffer capacity
Acid-Base Titrations
The general shape for a titration curve for a monoprotic acid: pH
Equivalence point
Region of high buffer capacity
pKa
mL base added
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28. pH is the negative logarithm of the hydrogen ion concentration.
pH Scale
pH is the negative logarithm of the hydrogen ion concentration.
pH = -log [H+]
Similar definition is made for the [OH-]:
P OH = - log [OH-]
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29. pH [H+]= 10-1M pH = – log [H+] Log scale means 10X change per unit!
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30. pH Scale pKw = pH + pOH at 25oC 14 = pH + pOH
[H+] = [OH-]  the solution is neutral (pH=7).
[H+]  [OH-]  the solution is acidic (pH 7).
[H+]  [OH-]  the solution is alkaline (pH 7).
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31. pH Scale lecture3 Example [OH-] pH [H3O+] HCl (4%) 1 X 10-14 1 X 100
1  X 100
Stomach acid
1  X 10-13 1
1  X 10-1
Lemon juice
1  X 10-12 2
1  X 10-2
Vinegar
1  X 10-11 3
1  X 10-3
Soda
1  X 10-10 4
1  X 10-4
Rainwater (unpolluted)
1  X 10-9 5
1  X 10-5
Milk
1  X 10-8 6
1  X 10-6
Pure water
1  X 10-7 7
Egg whites 8
Baking Soda 9
Ammonia 10 11
Drano® 12
NaOH (4%) 13 14
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32. pH Scale Measures the degree of acidity (0 – 14)
Most biologic fluids are in the pH range from 6 – 8
A small change in pH actually indicates a substantial change in H+ and OH- concentrations.
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33. Buffers A substance that eliminates large sudden changes in pH.
Buffers help organisms maintain the pH of body fluids within the narrow range necessary for life.
Are combinations of H+ acceptors and donors forms in a solution of weak acids or bases
Work by accepting H+ from solutions when they are in excess and by donating H+ when they have been depleted.
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34. Buffers
A pH buffer is a solution that resists changes in pH
A pH buffer contains a weak acid (HA) and its conjugate base (A-); or a weak base (A-) and its conjugate acid.
If a strong base (OH-) is added to a buffered solution, the weak acid in the buffer (HA) will react with OH- to give H2O and the weak base (A-). This results in converting a strong base (OH-) into a weak base (A-). As a result, the pH will slightly increase.
HA + OH- ➔ H2O + A-
If a strong acid acid (H+) is added to a buffered solution, the weak base in the buffer (A-) will react with the (H+) ion to give HA. This results in converting a strong acid H+ into a weak acid HA. As a result, the pH will slightly decrease.
A- + H+ ➔ HA

35. The main buffer system of the human blood is A. H2CO3 - HCO3 B
The main buffer system of the human blood is A.H2CO3 - HCO3 B.H2CO3 - CO32- C.CH3COOH - CH3COO- D.NH2CONH2 - NH2CONH+
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36. In this system, carbon dioxide (CO2) combines with water to form carbonic acid (H2CO3), which in turn rapidly dissociates to form hydrogen ions and bicarbonate (HCO3- ). The carbon dioxide - carbonic acid equilibrium is catalyzed by the enzyme carbonic anhydrase; the carbonic acid - bicarbonate equilibrium is simple proton dissociation/association and needs no catalyst
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37.  Which among the following acids is abundant in Grapes, Bananas and Tamarind? [A]Lactic Acid [B]Oxalic Acid [C]Salicylic Acid [D]Tartaric Acid
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38. Thank you
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