Chemistry Practicals For HSC-Part 1 (XI -Science Group) - Titration - General Descripttion - DJ Sindh Government College

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TITRATION

EQUATIONS:
NaOH + HCl ⟶ NaCl + H₂O
2KOH + H₂SO₄ ⟶ K₂SO₄ + 2H₂O
KOH + HNO₃ ⟶ KNO₃ + H₂O
2NaOH + H₂C₂0₄.2H₂0 ⟶ Na₂C₂0₄ + 4H₂0
2KOH + H₂C₂0₄.2H₂0 ⟶ ₂C₂0₄ + 4H₂0
2HCI + Na₂CO₃ ⟶ 2NaCI + CO₂ + H₂O
H₂SO₄ + K₂CO₃ ⟶ K₂SO₄ + CO₂ + 2H₂0
2HNO₃ + K₂CO₃ ⟶ 2KNO₃ + CO₂ + H₂O
H₂SO₄ + Na₂CO₃ ⟶ Na₂SO₄ + CO₂ + H₂O

2KMn0₄ + 3H₂SO₄ ⟶ K₂SO₄ + 3H₂0 + 2MnSO₄ + 5[O]
10FeSO₄ + 5H₂SO₄ + 5[0] ⟶ 5Fe₂(SO₄)₃ + 5H₂0

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2KMn0₄ + 10FeSO₄ + 8H₂SO₄ ⟶ K₂SO₄ + 2MnSO₄ + 5Fe₂(SO₄)₃ + 8H₂0

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2KMn0₄ + 3H₂SO₄ ⟶ K₂SO₄ + 3H₂0 + 2MnSO₄ + 5[O]
5H₂C₂O₄ + 5[0] ⟶ 10CO₂ + 5H₂0

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2KMn0₄ + 5H₂C₂O₄ + 3H₂SO₄ ⟶ K₂SO₄ + 2MnSO₄ + 10CO₂ + 8H₂0

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IONIC EQUATION FOR ACID — BASE
Na⁺ + OH^- + H⁺ + Cl^- ⟶ Na⁺ + Cl^- + H₂O

2K⁺ + 20H^- + 2H⁺ + SO₄^2- ⟶ 2K⁺ + SO₄^2- + 2H₂0

K⁺ + OH^- + H⁺ + NO₃^- ⟶ K⁺ + NO₃^- + H₂0

2Na⁺ + 20H^- + 2H⁺ + C₂0₄^2- ⟶ 2Na⁺ + C₂0₄^2- + 2H₂0

2K⁺ + OH^- + 2H⁺ + C₂0₄^2- ⟶ 2K⁺ + C₂0₄^2- + 2H₂0

2H⁺ + 2Cl^- + 2Na⁺ + CO₃^2- ⟶ 2Na⁺ + 2Cl^- + CO₂ + H₂O

2H⁺ + SO₄^2- + 2K⁺ + CO₃^2- ⟶ 2K⁺ + SO₄^2- + CO₂ + H₂O

2H⁺ + 2NO₃^- + 2K⁺ + CO₃^2- ⟶ 2K⁺ + 2NO₃^- + CO₂ + H₂0

2H⁺ + SO₄^2- + 2Na⁺ + CO₃^2- ⟶ 2Na⁺ + SO₄^2- + CO₂ + H₂O

THEORY
FOR ACID-BASE TITRATION:
Titration is a process in which the fixed volume of a solution taken by means of pipette into conical flask is compared with the volume of solution added from burette upto end point which is obtained by colour change. The purpose of titration is to determine the unknown strength of a solution.
Base is a substance which gives OH^- ion in aqueous solution. When an acid solution reacts completely with base solution or vice versa, a salt is formed.
Neutralization: In acid-base reaction H⁺ ion from an acid and OH^- ion from a base form H₂O, salt is also formed process is called neutralization. This is indicated by end point and is observe by suitable indicator those having different colors in different medium.
Strong acid and strong base ionize completely in aqueous solution while weak acid and weak base ionize only partially in aqueous solution, these form acidic and basic salts which hydrolyse to change the pH.

Na₂CO₃ + H₂O ⟶ NaOH + H₂CO₃

(Basic salt) + (water) (Strong base) (Weak acid)

where Basic (pH > 7)

FOR REDOX TITRATION:
Titration is a process in which the fixed volume of a solution taken by means of pipette Into conical flask is compared with the volume of solution added from burette upto end point which is obtained by colors change. The purpose of titration is to determine the unknown strength of a solution using standard solution.
Redox Titration: The type of titration in which one reactant in oxidized and other reduced are know as redox titration.
Oxidation is a process in which reducing Agent loses electron and absorbs oxygen, so the oxidation number increases.

Fe²⁺ ⟶ Fe³⁺ + e^-

2FeSO₄ + H₂SO₄ + [0] ⟶ Fe₂(SO₄)₃ + H₂O

Reduction is a process in which oxidizing agent gain electron and loses oxygen, so oxidation number decreases

Mn⁷⁺ + 5e^- ⟶ Mn²⁺

2KMnO₄ + H₂SO₄ ⟶ K₂SO₄ 2MnSO₄ + 3H₂0 + 5[O]

Oxidizing strength of KMnO₄ increase in the presence of H₂SO₄, so H₂SO₄ is required in redox titration. KMnO₄ is coloured substance so it acts as indicator, therefore no external indicator is required.
Reaction between KMnO₄ and oxalic acid is very slow because oxalic acid is a covalent organic compound. So the Titration flask is heated to about 60 — 70°C before adding KMnO₄ from the burette.

PROCEDURE:
Strong Base Vs Stron Acid OR Strong Base Vs Weak Acid

1. Wash burette, pipette and conical flask with water.
2. Rinse burette with base and pipette with acid.
3. Do not rinse the conical flask.
4. Fill the burette with base upto Zero mark.
5. Pipette out 10 cm³ of acid into the conical flask.
6. Add one or two drops of phenolphthalein as indicator.
7. Titrate the base in the burette with the acid in conical flask. The burette solution is added drop by drop into the conical flask.
8. Shake the flask after each addition, The end point is indicated by colour change from colourless to light pink.
9. Note the end point.
10. wash the conical flask with water and repeats the same process for at least three times to obtain two similar readings.


Strong Acid Vs Weak Base
1. Wash burette, pipette and conical flask with water.
2. Rinse burette with acid and pipette with base solution.
3. Do not rinse the conical flask.
4. Fill the burette with acid upto Zero mark.
5. Pipette out 10 cm³ of base into the conical flask.
6. Add one or two drops of methyl orange as indicator.
7. Titrate the acid in the burette with the base in conical flask. The burette solution is added drop by drop into the conical flask.
8. Shake the flask after each addition, The end point is indicated by colour change from yellow to light pink.
9. Note the end point.
10. Wash the conical flask with water and repeat the same process for at least three times to obtain two similar readings.


Redox Titration
1. Wash all the apparatus with water.
2. Rinse burette with KMnO₄ and pipette with reducing agent.
3. Do not rinse the conical flask.
4. Fill the burette with base upto Zero mark.
5. Pipette out 10 cm³ of given reducing agent into the conical flask.
6. Add one test tube of dilute H₂SO₄ (In case of oxalic acid as a reducing agent titration flask is heated to about 60 - 70°C before titration).
7. Titrate KMnO₄ in the burette with the reducing agent in conical flask. The burette solution is added drop by drop into the conical flask.
8. Shake the flask after each addition, the end point is indicated by colour change from colourless to light pink.
9. Note the end point.
10. Wash the conical flask with water repeat the same process for at least three times to obtain two similar readings.

OBSERVATION:

S.NO.	Initial reading	Final reading	Difference	Concordant reading
1.	cm3	cm3	cm3	cm3
2.	cm3	cm3	cm3
3.	cm3	cm3	cm3

• Solution in burette = ______ (Strong Acid Or Strong Base)
• Solution in conical flask = ________ (Weak Acid Or Weak Base)
• Indicator used =  _______ (e.g Phenophthalein for Strong Base)
• Normality of standard solution = N₁ = ___ N
• Volume of standard solution = V₁ = 10 ml
• Normality of solution of unknown strength = N₂ = ?
• Volume of solution of unknown strength = V₂ = ?

CALCULATION:
Standard solution Vs Solution of unknown strength

N₁V₁ = N₂V₂

Equivalent mass = Molecular mass / Acidity or Basicity or change in oxidation state
Amount = Normality (N₂) x equivalent mass x volume of solution in cm³ / 1000

RESULT:

• Normality of given ________ solution = ______ N
• Amount of ______ in the given solution = gms / ___ dm³ or ____ cm³

Acidity Of Base:

Base	Acidity	Equivalent mass
NaOH	1	40
KOH	1	56
Na2CO3	2	53
K2CO3	2	69

Basicity Of Acid

Acid	Basicity	Equivalent mass
HCl	1	36.5
H2SO4	2	49
HNO3	1	63
C2H204.2H20	2	63

Oxidizing Agent

Oxidizing agent	No. of electron gained	Equivalent mass
KMnO4	5	31.6

Reducing Agent

Reducing Agent	No. of electron lost	Equivalent mass
FeSO4.7H20	1	278
FeSO4.(NH4)2SO4.6H20	1	392
H2C204.2H20	2	63