An Overview of Class 11 Chemistry Preparation Of Standard Solution Of Oxalic Acid Experiment
Standard liquid solutions, like acids, are readily available and simple to prepare. By measuring a solid mass and dissolving it into a volumetric flask with a known volume of solution, one can prepare a standard solution. In this experiment with an oxalic acid example, the preparation of the standard solution is explained in detail. Oxalic acid is a dicarboxylic acid. It is indeed a white crystalline substance that dissolves in water to produce a colourless solution.
Table of Content
Aim
Apparatus Required
Theory
Procedure
Observations
Result
Aim
To prepare the \[\dfrac{M}{{10}}\] standard solution of oxalic acid.
Apparatus Required
250mL beaker
250mL Volumetric flask
Glass rod
Funnel
Pipette
Watch glass
Wash bottle
Chemical balance
Weight box
Theory
A standard solution is one whose concentrations are precisely known. C2H2O4 is a primary standard. Oxalic acid molecular mass is 126. To prepare the \[\dfrac{M}{{10}}\] standard solution of oxalic acid,
Molarity= \[W = M \times V\]
W is the oxalic acid mass in grams.
M is the oxalic acid molecular mass in grams.
V is the volume of the solution, litres.
12.6 g of oxalic acid must be dissolved per litre of water for the preparation of \[\dfrac{M}{{10}}\] oxalic acid solution. As a substitute, \[\dfrac{{12}}{6} = 3.15\,gm\] of oxalic acid should indeed be dissolved in water to obtain precisely 250 ml of solution.
Procedure
Preparation of Standard Solution of Oxalic Acid
Wash the watch glass using distilled water and dry it. Weigh the dry watch glass and record the reading.
Make a precise weight measurement of 3.15 g of C2H2O4 on the watch glass and record the weight.
Using a funnel, delicately and cautiously transfer the C2H2O4 from the watch glass to a dry, clean 250mL beaker. For transferring the particles stuck to the watch glass into the funnel, rinse the watch glass using distilled water. Not more than 50mL of distilled water should be used for this purpose.
Until the rigid oxalic acid dissolves, stir the solution in the beaker using a glass rod.
Transfer the solution in the beaker to the volumetric flask using a glass rod and funnel.
Using a wash bottle, gently pour sufficient distilled water into the flask to fill it to just beneath the mark that has been carved on it.
When the lower layer of the meniscus almost reaches the line on the flask, add the final few millilitres of distilled water drop-wise using a pipette.
Put a stopper on the volumetric flask as well as give it a little shake to evenly distribute the solution. Mark it as \[\dfrac{M}{{10}}\] C2H2O4 solution.
Observations
Result
The result of the chemistry experiment on the preparation of \[\dfrac{M}{{10}}\] oxalic acid solution verified that:-
A 250 ml or \[\dfrac{M}{{10}}\] oxalic acid standard solution has been successfully prepared.
Precautions
Handle chemicals and apparatus with caution.
Every apparatus should be rinsed with distilled water and dried before starting the experiment.
The solution preparation should be done while wearing an apron.
Avoid spilling the chemicals on the weighing balance during weighing.
To make the solution uniform, it must be thoroughly shaken.
When preparing the solution, the solvent must indeed be added so that its lower meniscus touches the flask's mark.
After the completion of the experiment, wash your hands thoroughly.
Lab Manual Questions
1. Why should the funnel and beaker be rinsed while preparing the solution?
Ans: Rinsing prevents any dissolved solute from being lost by ensuring that all particles enter the volumetric flask from the remaining solution in the funnel and the beaker.
2. What is the aim of transferring solutions employing glass rods?
Ans: Solutions are poured using glass rods to prevent spillage. A glass rod placed against a beaker's pouring edge enables the solution to run down the glass rod and into the collecting vessel, as opposed to splashing beyond the lip.
3. Why doesn't the pipette blow out the final drop?
Ans: Due to surface tension, a tiny drop of liquid remains in the pipette after the last drop is added, preventing the last drop from being blown out. Furthermore, the design of pipettes ensures that this drop won't have an impact on the empirical value.
4. Why is it necessary to close the volumetric flask once the solution is prepared?
Ans: The solute's ability to interact with the moisture of the oxygen or absorb carbon dioxide or some additional pollutant in the air is dependent on the solute.
Viva Questions
1. Define molarity.
Ans: The number of moles of a solute per litre of a solution is known as molarity. Another term for molarity is the molar concentration of a solution.
2. What is the formula to calculate the molarity of oxalic acid?
Ans: Molarity=\[W = M \times V\].
3. How does oxalic acid act?
Ans: Reducing agent.
4. What is the correct way of diluting an acid?
Ans: The correct way of diluting an acid is to add acid into the water with constant stirring.
5. Mention two uses of oxalic acid.
Ans: Oxalic acid is used to remove ink stains, and as acid rinses in laundries.
6. What is the purpose of using the oxalic acid standard solution?
Ans: Oxalic acid standard solution can be employed to estimate an alkali solution's undetermined concentration.
7. What is the general formula of hydrated oxalic acid?
Ans: C2H2O4.2H2O
8. What kind of water is used for the preparation of the standard solution?
Ans: Distilled water is used for the preparation of standard solutions.
9. Define normality.
Ans: Following the conventional definition, normality is defined as the quantity of solute (measured in grams or moles) prevalent per litre of a solution.
Practical Based Questions
What is the other name for oxalic acid?
Ethanedioic acid
Boric acid
Sulfonic acid
Lactic acid
Ans: The other name of oxalic acid is ethanedioic acid.
What is the conjugate base of oxalic acid?
Acetate
Oxalate
hydroxide
None of the three options
Ans: The conjugate base of oxalic acid is the oxalate ion.
What is the molecular mass of oxalic acid?
116
126
136
None of the three options
Ans: The molecular mass of oxalic acid is 126.
What type of compound is oxalic acid?
Strong base
Weak base
Strong acid
Weak acid
Ans: Oxalic acid is a weak acid.
What type of instrument is used in this experiment to add the last drop to avoid the extra drops in the solution while transferring the solution to a volumetric flask?
Dropper
Wash bottle
Pipette
None of the above three options
Ans: Pipette is used to avoid extra drops during solution preparation
What measurement is used to represent the standard solution's strength?
Gram per litre
Milligram per litre
Moles per litre
None of the above three options
Ans: The standard solution strength is expressed using moles per litre.
How is the strength of a particular solution determined?
Law of mass action
Equivalent law
Henry’s law
None of the three options
Ans: Equivalent law is used to determine the strength of a particular solution.
How does oxalic acid act for metal cations?
Reducing agent
Oxidizing agent
Chelating agent
None of the above
Ans: Oxalic acid acts as a chelating agent for metal cations.
How does distilled water act in chemical laboratories?
Indicator
Solvent
Universal solvent
None of the three options
Ans: Distilled water acts as a universal solvent in chemical laboratories.
What is the stability of the oxalic acid standard solution?
Stable
Unstable
Vigorous
None of the three options
Ans: Oxalic acid standard solution serves as a stable solution.
Conclusion
This Chemistry experiment on the preparation of \[\dfrac{M}{{10}}\] oxalic acid solution infers that oxalic acid is also known as ethanedioic acid. C2H2O4 is the chemical formula for oxalic acid. The concentration of the oxalic acid standard solution can be determined with high accuracy. It is prepared to utilize only pure chemicals, and standardization is used to determine the precise concentration. A primary standard is a chemical that is utilized to standardize an extremely pure solution. While making the oxalic acid solution, a total of 50 ml of distilled water should not be utilized.
FAQs on Class 11 Chemistry Preparation Of Standard Solution Of Oxalic Acid Experiment
1. How do you accurately prepare an M/10 oxalic acid solution for the Class 11 Chemistry practical exam?
To accurately prepare an M/10 oxalic acid solution:
- Weigh exactly 3.15 g of pure oxalic acid (C2H2O4·2H2O) using a chemical balance.
- Transfer it to a clean 250 mL beaker, using a glass rod and funnel. Rinse all apparatus with distilled water to ensure complete transfer.
- Dissolve in about 50 mL of distilled water, then pour into a 250 mL volumetric flask.
- Add distilled water dropwise up to the mark, ensuring the lower meniscus touches the calibration line.
- Stopper and shake the flask for uniform mixing, then label it as M/10 oxalic acid solution.
2. What are the most commonly asked exam questions regarding the preparation of standard oxalic acid solution?
Frequently asked exam questions include:
- Calculation of molarity or normality using given masses and volumes.
- Procedure steps for preparation and the importance of rinsing apparatus.
- Precautions to ensure accuracy in standard solution preparation.
- Distinction between primary and secondary standards.
3. Which practical errors can lead to incorrect concentration when preparing oxalic acid solutions, and how can they be avoided?
Common errors and avoidance strategies:
- Not weighing oxalic acid precisely – always use a calibrated balance.
- Loss of solute during transfer – rinse the beaker, funnel, and watch glass thoroughly.
- Addition of excess water – fill up to the mark only, not above.
- Poor mixing – shake the flask thoroughly after preparation.
- Use only distilled water to prevent impurities.
4. Why is oxalic acid considered a primary standard in volumetric analysis for the CBSE Chemistry exam?
Oxalic acid serves as a primary standard because:
- It is highly pure, stable, and non-hygroscopic.
- Its molecular mass can be accurately determined.
- It does not absorb moisture or react with atmospheric CO2, ensuring consistent molarity.
5. How can you use the M/10 oxalic acid solution in titration experiments, and what is its purpose in exam-oriented questions?
M/10 oxalic acid solution is used to titrate against alkali (e.g., sodium hydroxide) to determine the unknown concentration of the base. Practical questions often ask you to:
- Write the balanced reaction equation.
- Perform calculations using the molarity formula M1V1 = M2V2.
- Explain end-point detection using indicators.
6. What are the main precautions to follow during the preparation of an M/10 oxalic acid solution to score full practical marks?
Key precautions include:
- Always use gloves and a lab apron to ensure safety.
- Make sure all glassware is clean and rinsed with distilled water.
- Weigh oxalic acid accurately.
- Transfer all the solute completely, rinsing the vessels as necessary.
- Fill the flask exactly to the mark at eye level to avoid parallax error.
- Mix the solution thoroughly before use.
7. According to the CBSE 2025–26 syllabus, what marking scheme is followed for questions on standard solution preparation, and what type of answers fetch high marks?
According to the latest CBSE marking scheme, practical-based questions on standard solution preparation are awarded marks for:
- Accurate calculation and formula use – 1 mark
- Stepwise description of the procedure – 2 marks
- Viva or reasoning (like why a particular step is done) – 1 mark
- Precaution and safety awareness – 1 mark
8. What is the key difference between molarity and normality, and which should be used when reporting oxalic acid solution strength in board practicals?
Molarity refers to moles of solute per litre of solution, whereas normality is gram equivalents per litre. For oxalic acid, molarity is commonly used in CBSE board practicals unless the reaction involves equivalents, in which case normality may be asked. Always report in the unit specified in the question.
9. How does the improper handling or exposure of oxalic acid standard solution to air affect exam results?
If an oxalic acid solution is left open, it may absorb moisture or CO2 from the air, altering its concentration. This can lead to inaccurate titration outcomes and loss of marks in board exams. Always stopper the flask tightly after preparation.
10. Can you apply the method for preparing M/10 oxalic acid solution to other acids, and what changes would you need to make?
Yes, the basic method applies to other acids but requires calculating the exact mass needed based on the acid's molecular weight and desired molarity. For acids that are not primary standards or are hygroscopic, additional precautions such as standardization against a primary standard may be needed.
