In chemistry labs, accuracy is everything especially during titrations and experiments. That’s where standard solutions come in. A standard solution is a solution with a known and exact concentration. It’s prepared very carefully so that it can be used to find out the concentration of other unknown solutions. Whether you’re studying for NEET, JEE, or just doing a practical lab, learning how to prepare a standard solution is a must. In this article, we’ll focus on one of the most commonly used oxalic acid solutions and understand how to make it step by step.

What is Oxalic Acid?

Oxalic acid is a colourless, crystalline organic compound that’s often used in labs for titration. Its chemical formula is H2C2O4.2H2O. It's a weak acid but works well as a primary standard because it’s stable, pure, and easy to weigh accurately. That’s why it’s commonly used to prepare standard solutions in chemistry experiments.

Chemistry Notes Free PDFs

Required Materials for Oxalic Acid Experiment 

• Chemical balance
• Watch glass
• Weight box
• 250ml beaker
• Glass rod
• 250ml measuring flask
• Wash bottle
• Weighing tube
• Oxalic acid
• Funnel
• Funnel stand
• Distilled water

• The hydrated form of oxalic acid is represented as C2H2O4.2H2O.
• The molecular weight of Oxalic Acid is 126.
• To prepare a M/10 oxalic acid solution, 12.6 g of oxalic acid should be dissolved per litre of the solution.
• Alternatively, precisely 3.15 g of oxalic acid crystals should be dissolved in water to produce exactly 250 ml of the solution.

Step by step Procedure for Oxalic Acid Experiment

• Begin by washing a watch glass with distilled water and drying it.
• Record the exact weight of the clean and dried watch glass in your notebook.
• Accurately weigh 3.15 g of oxalic acid on the watch glass and record this weight in your notebook.
• Gently and carefully transfer the oxalic acid from the watch glass into a clean and dry measuring flask using a funnel.
• Use a wash bottle to wash the watch glass with distilled water, ensuring to move any remaining particles into the flask.
• When doing this, make sure the volume of distilled water used does not exceed 50 ml.
• Wash the funnel several times with distilled water, using a wash bottle to move any remaining particles into the measuring flask. Again, the distilled water used for this purpose should not exceed 50 mL.
• Rinse the funnel carefully with distilled water, ensuring to transfer any solution remaining on the funnel into the measuring flask.
• Shake the measuring flask until the oxalic acid is dissolved.
• Add distilled water to the measuring flask using a wash bottle until the level is just below the etched mark on the flask.
• Add the final few mL of distilled water drop by drop into the measuring flask until the lower meniscus level just touches the mark.
• Place the stopper on the mouth of the flask and gently shake to make the solution uniform. This is your M/10 oxalic acid solution.

Observations:

Result of Oxalic Acid Experiment

A 250cm3 decimolar or (M/10) solution of oxalic acid has been prepared.

Safety Precautions While Preparing Oxalic Acid Solution

• The weighing of oxalic acid crystals requires weights of 2g + 1g + 100mg + 50mg.
• Ensure to wash the watch glass thoroughly so that not a single crystal of oxalic acid remains on it.
• The last few drops should be added using a pipette to prevent overfilling the measuring cylinder with distilled water.
• If it is necessary to titrate oxalic acid or oxalate, add the required amount of dilute H2SO4 and heat the flask to 60 °C - 70 °C.

Applications of Oxalic Acid Solution

• It is mainly used to find the exact strength of potassium permanganate(KMnO4) in redox titrations.
• Oxalic Acid solution is used in school and college labs for practicals, and in industries for accurate chemical testing, like in water treatment and pharma labs.

Summary and Key Points for Quick Revision

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