CBSE Class 11 Chemistry Volumetric Assignment

PREPARATION OF STANDARD SOLUTION

Expt No:_______
Date: _________

Aim: To prepare a \(0.1\text{ N}\) solution of oxalic acid.
Requirements: \(100\text{ ml}\) volumetric flask, oxalic acid crystals (AR Quality), Weighing bottle, Funnel, Glass rod, wash bottle, balance etc
Theory: A solution whose concentration is known exactly is called a standard solution. Normality may be defined as the number gram equivalents of solute per liter of the solution and is represented by "N"

\(\text{Normality} = \frac{\text{Mass of solute} \times 1000}{\text{Equivalent mass} \times \text{volume of solution (ml)}}\)

Equivalent mass of oxalic acid dihydrate (\(\text{H}_2\text{C}_2\text{O}_4 \cdot 2\text{H}_2\text{O}\)):
RMM of oxalic acid dihydrate = \(126\text{ amu}\); and number of replaceable hydrogen in oxalic acid = \(2\)
Therefore equivalent mass of oxalic acid dihydrate = \(\frac{126}{2} = 63\text{ amu}\).

Note: Normality of \(1\text{L}\) of solution, which contains \(63\text{ g}\) of oxalic acid dihydrate = \(1\text{N}\)

Procedure: Weigh \(0.6300\text{ g}\) of Oxalic acid crystals (AR grade), accurately in a weighing bottle and transfer into a clean funnel placed over a \(100\text{ ml}\) standard volumetric measuring flask. Wash down the crystals carefully into the flask by a jet of distilled water. Wash the funnel also down into the flask. Dissolve the crystals completely and then make up the solution to \(100\text{ ml}\) mark. Shake well to make a homogeneous solution.

Calculation:
Mass of oxalic acid crystals = \(X\text{ g} = 0.6300\text{ g}\)
Volume of oxalic acid solution prepared = \(V\text{ ml} = 100\text{ ml}\)
Normality of the oxalic acid solution = \(N = \frac{X\text{ g} \times 1000}{63 \times V\text{ ml}} = \frac{0.6300 \times 1000}{63 \times 100} = 0.1\text{ N}\)

Result: The normality of the oxalic acid solution = \(0.1\text{ N}\)

VOLUMETRIC ANALYSIS - I

ESTIMATION OF SODIUM HYDROXIDE

Experiment Number:________
Date:___________

Aim: To estimate the strength of a given solution of sodium hydroxide solution by titrating it against a standard solution of oxalic acid.
Requirements: Burette, Pipette, Conical flask, weighing bottle, oxalic acid crystals (A.R. Grade) Balance, Funnel, Glass rod, wash bottle etc.
Indicator used: Phenolphthalein
Theory: The estimation is based on the reaction between oxalic acid and sodium hydroxide as per the following chemical equation:

\(\text{H}_2\text{C}_2\text{O}_4 + 2\text{NaOH} \rightarrow \text{Na}_2\text{C}_2\text{O}_4 + 2\text{H}_2\text{O}\)

Normality of the given solution is calculated using the law of equivalence formula:
\(N_aV_a = N_bV_b\)
Where,
\(N_a =\) Normality of the acid; \(N_b =\) Normality of the base
\(V_a =\) Volume of the acid used; \(V_b =\) Volume of the base used.

Estimation of Sodium Hydroxide:
1. Pipette out \(20\text{ ml}\) (Wash the pipette thoroughly with distilled water followed by rinsing with \(\text{NaOH}\) solution) of the given \(\text{NaOH}\) into a clean conical flask. (Wash the conical flask thoroughly with distilled water only)
2. Add one drop of phenolphthalein indicator to the flask.
3. Titrate this pink colored solution against standard oxalic acid solution taken in a clean burette. (Wash the burette thoroughly with distilled water followed by rinsing with oxalic acid solution)
4. End point is marked by the disappearance of the pink colour.
5. End point of the titration is recorded as titre value in a tabular form.
6. Repeat the titration till concordant values are obtained. [Record only two titre (concordant) readings in the table]
7. Using the titre value concentration of the given \(\text{NaOH}\) is calculated.

Calculation:
Volume of \(\text{NaOH}\) used = \(V_b = 20\text{ ml}\)
Volume of Oxalic acid used = \(V_a = 20.0\text{ ml}\)
Normality of oxalic acid = \(N_a = 0.1\text{ N}\)
Normality of \(\text{NaOH} = N_b = \frac{N_a V_a}{V_b} = \frac{0.1 \times 20.0}{20} = 0.1\text{ N}\)
Concentration of \(\text{NaOH} = \text{Normality} \times \text{Equivalent mass} = N_b \times 40 = 0.1 \times 40 = 4.0\text{ g/L}\)

Result:
1. Normality of \(\text{NaOH} = 0.1\text{ N}\)
2. Concentration of \(\text{NaOH} = 4.0\text{ g/L}\)

VOLUMETRIC ANALYSIS - II

ESTIMATION OF POTASSIUM HYDROXIDE

Experiment Number: ______
Date: _______________

Aim: To estimate the strength of a given solution of potassium hydroxide solution by titrating it against a standard solution of oxalic acid.
Requirements: Burette, Pipette, Conical flask, weighing bottle, oxalic acid crystals (AR Grade) Balance, Funnel, Glass rod, wash bottle etc.
Indicator used: Phenolphthalein
Theory: The estimation is based on the reaction between oxalic acid and potassium hydroxide as per the following chemical equation:

\(\text{H}_2\text{C}_2\text{O}_4 + 2\text{KOH} \rightarrow \text{K}_2\text{C}_2\text{O}_4 + 2\text{H}_2\text{O}\)

Normality of the given solution is calculated using the law of equivalence formula:
\(N_aV_a = N_bV_b\)
Where,
\(N_a =\) Normality of the acid; \(N_b =\) Normality of the base
\(V_a =\) Volume of the acid used; \(V_b =\) Volume of the base used.

Estimation of Potassium Hydroxide:
1. Pipette out \(20\text{ ml}\) (Wash the pipette thoroughly with distilled water followed by rinsing with \(\text{KOH}\) solution) of the given \(\text{KOH}\) into a clean conical flask. (Wash the conical flask thoroughly with distilled water only)
2. Add one drop of phenolphthalein indicator to the flask.
3. Titrate this pink colored solution against standard oxalic acid solution taken in a clean burette. (Wash the burette thoroughly with distilled water followed by rinsing with oxalic acid solution)
4. End point is marked by the disappearance of the pink colour.
5. End point of the titration is recorded as titre value in a tabular form.
6. Repeat the titration till concordant values are obtained. [Record only two titre (concordant) readings in the table]
7. Using the titre value concentration of the given \(\text{KOH}\) is calculated.

Calculation:
Volume of \(\text{KOH}\) used = \(V_b = 20\text{ ml}\)
Volume of Oxalic acid used = \(V_a = 20.0\text{ ml}\)
Normality of oxalic acid = \(N_a = 0.1\text{ N}\)
Normality of \(\text{KOH} = N_b = \frac{N_a V_a}{V_b} = \frac{0.1 \times 20.0}{20} = 0.1\text{ N}\)
Concentration of \(\text{KOH} = \text{Normality} \times \text{Equivalent mass} = N_b \times 56 = 0.1 \times 56 = 5.6\text{ g/L}\)

Result:
1. Normality of \(\text{KOH} = 0.1\text{ N}\)
2. Concentration of \(\text{KOH} = 5.6\text{ g/L}\)

VOLUMETRIC ANALYSIS - III

ESTIMATION OF HYDROCHLORIC ACID

Experiment Number: .........
Date: .............

Aim: To estimate the strength of a given solution of hydrochloric acid solution by titrating it against a standard solution of sodium carbonate.
Requirements: Burette, Pipette, Conical flask, weighing bottle, sodium carbonate crystals (AR Grade) Balance, Funnel, Glass rod, wash bottle etc.
Theory: The estimation is based on the reaction between \(\text{HCl}\) and \(\text{Na}_2\text{CO}_3\) as per the following chemical equation:

\(2\text{HCl} + \text{Na}_2\text{CO}_3 \rightarrow 2\text{NaCl} + \text{H}_2\text{O} + \text{CO}_2\)

Normality of the given solution is calculated using the law of equivalence formula:
\(N_aV_a = N_bV_b\)
Where,
\(N_a =\) Normality of the acid; \(N_b =\) Normality of the base
\(V_a =\) Volume of the acid used; \(V_b =\) Volume of the base used.

Indicator used: Methyl Orange
Procedure: Preparation of \(\text{Na}_2\text{CO}_3\) solution (standard \(0.1\text{N}\))
Weigh \(0.5300\text{ g}\) of \(\text{Na}_2\text{CO}_3\) crystals (AR grade), accurately in a weighing bottle and transfer into a clean funnel placed over a \(100.0\text{ ml}\) standard volumetric measuring flask. Wash down the crystals carefully into the flask by a jet of distilled water. Wash the funnel also down into the flask. Dissolve the crystals completely and then make up the solution to \(100\text{ ml}\) mark. Shake well to make a homogeneous solution.

Mass of \(\text{Na}_2\text{CO}_3\) crystals = \(X\text{ g} = 0.5300\text{ g}\)
Volume of solution prepared = \(V\text{ ml} = 100\text{ ml}\)
Normality of the \(\text{Na}_2\text{CO}_3\) solution = \(N = \frac{X\text{ g} \times 1000}{53 \times V\text{ ml}} = \frac{0.5300 \times 1000}{53 \times 100} = 0.1\text{ N}\)

Estimation of Hydrochloric acid:
1. Pipette out \(20\text{ ml}\) (Wash the pipette thoroughly with distilled water followed by rinsing with \(\text{Na}_2\text{CO}_3\) solution) of the given \(\text{Na}_2\text{CO}_3\) into a clean conical flask (Wash thoroughly with distilled water only).
2. Add a drop of Methyl Orange indicator to the flask.
3. Titrate this yellow colored solution against hydrochloric acid solution taken in a clean burette. (Wash the burette thoroughly with distilled water followed by rinsing with \(\text{HCl}\) acid solution)
4. At the end point the colour of the solution changes from yellow to pink.
5. End point of the titration is recorded as titre value in a tabular form.
6. Repeat the titration till concordant values are obtained. [Record only two titre (concordant) readings in the table]
7. Using the titre value concentration of the given \(\text{HCl}\) is calculated.

Calculation:
Volume of \(\text{Na}_2\text{CO}_3\) used = \(V_b = 20\text{ ml}\)
Volume of \(\text{HCl}\) acid used = \(V_a = 20.0\text{ ml}\)
Normality of \(\text{Na}_2\text{CO}_3\) = \(N_b = 0.1\text{ N}\)
Normality of \(\text{HCl} = N_a = \frac{N_b V_b}{V_a} = \frac{0.1 \times 20}{20.0} = 0.1\text{ N}\)
Concentration of \(\text{HCl} = \text{Normality} \times \text{Equivalent mass} = N_a \times 36.5 = 0.1 \times 36.5 = 3.65\text{ g/L}\)

Result:
1. Normality of \(\text{HCl} = 0.1\text{ N}\)
2. Concentration of \(\text{HCl} = 3.65\text{ g/L}\)

CBSE Class 11 Chemistry Volumetric Assignment. Students are advised to refer to the attached assignments and practice them regularly. This will help them to identify their weak areas and will help them to score better in examination. Parents should download and give the assignments to their children for practice.

PREPARATION OF STANDARD SOLUTION

Expt No:_______

Date: _________

Aim: To prepare a 0.1N solution of oxalic acid.

Requirements: 100ml volumetric flask, oxalic acid crystals (AR Quality), Weighing bottle, Funnel, Glass rod, wash bottle, balance etc

Theory: A solution whose concentration is known exactly is called a standard solution.

Normality may be defined as the number gram equivalents of solute per liter of the solution and is represented by “N”

Equivalent mass of oxalic acid dihydrate (H₂C₂O₄.2H₂O)

RMM of oxalic acid dihydrate = 126 amu; and number of replaceable hydrogen in oxalic acid = 2

Therefore equivalent mass of oxalic acid dihydrate = 126/2 = 63 amu.

Note: Normality of 1L of solution, which contains 63g of oxalic acid dihydrate = 1N

Procedure: Weigh 0.6300 g of Oxalic acid crystals (AR grade), accurately in a weighing bottle and transfer into a clean funnel placed over a 100 ml. standard volumetric measuring flask. Wash down the crystals carefully into the flask by a jet of distilled water. Wash the funnel also down into the flask. Dissolve the crystals completely and then make up the solution to 100 ml. mark. Shake well to make a homogeneous solution.