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Oxalic acid, popularly known by the IUPAC name ethanedioic acid, is an organic molecule with the chemical formula HO2C-CO2H. It is thought to be the most basic dicarboxylic acid.
- Oxalic acid is a white crystalline solid prepared using a standard, such as a fundamental standard substance.
- When we dissolve the compound in water, it will form a colorless solution.
- The substance was given the name oxalic acid because it was obtained from the flowering plant genus Oxalis, often known as wood-sorrels.
- It is found naturally in many foods such as cocoa, green vegetables, nuts, sweet potatoes, turnip greens and star fruit.
- While compound is a common in many food items, prolonged skin contact or excessive absorption can pose significant risks.
- Oxalic acid is a limiting reactant that has a substantially higher strength than acetic acid.
Key Terms: Preparation of Standard Solution of Oxalic Acid, Oxalic Acid, Ethanedioic Acid, Process, Aim, Theory, Requirements, Procedure, Observations, Precautions, Weight of standard solution of oxalic acid.
Aim
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The aim of the experiment involves preparation of standard solution of oxalic acid ot titrating a sodium hydroxide solution against a standard solution of oxalic acid to determine its concentration (strength).
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Theory
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The amount of acid and base becomes chemically comparable at the end of a titration of a strong acid with a strong base, and the chemical process is known as the neutralization reaction.
- The hydrated formula of oxalic acid is C2H2O4.2H2O with a molecular mass equivalent to 126.
- For preparation of M/10 oxalic acid solution then you should dissolve 12.6 g of oxalic acid per litre of the solution.
- The pH of the solution changes dramatically at the endpoint.
- If you try to add a small amount of base/acid after the endpoint, the solution will become slightly alkaline or acidic.
- Alternatively, exact 250 ml of the solution can be prepared by dissolving 12.6 /4 = 3.15 g of crystals of oxalic acid in water.
Materials Required
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Materials required for the preparation of standard solution of oxalic acid are as follows:
- Weighing Tube
- 250ml Beaker
- Glass Rod
- Chemical Balance
- 250ml Measuring Flask
- Funnel Stand
- Distilled Water
- Watch Glass
- Wash Bottle
- Weight Box
- Oxalic Acid
- Funnel
Apparatus Setup
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The apparatus set for the preparation of standard solution of oxalic acid are as follows:
Preparation of Standard Solution of Oxalic Acid
Procedure
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The procedure required for the preparation of standard solution of oxalic acid is as follows:
- Grab a watch glass and thoroughly clean it with distilled water before drying it.
- Measure and write the exact amount of dried and clean watch glass in the notebook.
- Examine 3.15 g of oxalic acid on the watch glass and record the weight in the notebook.
- Using a funnel, gently and carefully transfer oxalic acid to a clean and dry measuring flask from the watch glass.
- Then, with the help of a wash bottle, wash the watch glass with distilled water to shift the particle position that has stuck to it into the foam.
- As a result, the amount of distilled water used should be at most 50 ml.
- To pass the solution attached to the funnel into the measuring flask, thoroughly wash the funnel with distilled water using a wash bottle.
- Tilt the measurement flask to dissolve the oxalic acid.
- Using a wash bottle, thoroughly fill the measuring flask with distilled water just below the engraved mark.
- Add the last few ml of distilled water drop by drop into the measuring flask until the lowered meniscus level reaches the mark.
- Put the cap on the flask's mouth and gently shake to ensure consistency throughout the solution.
Observation
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The observation for the experiment are as follows:
| Observation | Data |
|---|---|
| Weight of the watch glass | W1g |
| Weight of Oxalic acid | 3.150g |
| Weight of the watch glass + Oxalic acid | W1 + 3.15g |
| Volume of distilled water | 250cm3 |
Results
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250 cm3 of (M/10) solution or decimolar of oxalic acid is prepared.
Precautions
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The precaution while conducting the experiment are as follows:
- When weighing the oxalic acid crystals, use the following weights: 2g + 1g + 100mg + 5mg.
- Clean the watch glass thoroughly, making sure there isn't a single oxalic acid crystal remaining on it.
- To avoid an excess addition of distilled water to the mark above the neck of the measuring cylinder, use a pipette to add the last few drops.
- If titration of oxalic acid or oxalate is required, add the required dilution amount of H2SO4 and heat the flask to 60° - 70° C.
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Things to Remember
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- The dihydrate form of oxalic acid, with the formula C2H2O22H2O, is most commonly encountered in nature.
- Its compound is oxalate, which is likewise a metal cation chelating agent.
- The solution would be clear if the burette tap was left open for longer, but it would be more acidic than neutral.
- The balance was quite sensitive to the surroundings, which could have added to the experiment's unpredictability.
- This also decreases the number of unknown variables while also ensuring that the solutions are free of contamination.
- Repeat the experiment numerous times to limit the number of errors and uncertainties.
- Correctly read measurements by maintaining the eye at the proper level to get accurate results.
- Before beginning the experiment, double-check that all of the equipment is in working order.
Sample Questions
Ques: What is oxalic acid? (2 marks)
Ans: Oxalate, also known as oxalic acid, is a nutrient found in leafy greens, legumes, and most other plant foods. It's a naturally occurring substance that you obtain from your food. It is also produced by the body as a waste product. Oxalate-rich foods also contain other elements that your body requires for optimal health.
Ques: How do you standardize oxalic acid? (2 marks)
Ans: To the oxalic acid, add around 25 mL of deionized water and 3 drops of phenolphthalein. To dissolve the oxalic acid, swirl the mixture. Titrate the oxalic acid with NaOH after reading the buret to the nearest 0.01 mL. When the phenolphthalein's pale pink color lasts for 30 seconds, you've reached the finish point.
Ques: How will you prepare 0.1 M oxalic acid solution? (2 marks)
Ans: Oxalic acid has a molecular mass of 126. 12.6 g of oxalic acid should be dissolved per liter of the solution to make M/10 oxalic acid solution. Alternatively, dissolve 12.6 /4 = 3.15 g of oxalic acid crystals in water and dilute to exactly 250 ml.
Ques: How do you prepare a standard acid solution? (2 marks)
Ans: Dilution can also be used to create a standard solution. Bench acids like hydrochloric acid, sulphuric acid, and nitric acid are made by diluting commercial concentrated acids (stock solutions) with distilled water in various proportions.
Ques: Why is oxalic acid used to make standard solutions? (2 marks)
Ans: Oxalic acid is a material that can be weighed in its pure form, it is used to make standard solutions. Explanation: An oxalic acid standard is a known high purity chemical that may be dissolved in a known volume of solvent to produce a primary standard solution.
Ques: What is a standard solution? (2 marks)
Ans: A standard solution is a solution that contains a precisely known concentration of an element or compound in analytical chemistry. To make a specific volume, a known mass of solute is dissolved.
Ques: How would you prepare 250ml M 20 oxalic acid? (2 marks)
Ans: H2C2O4, 2H2O is the molecular formula of solid crystalline oxalic acid. It has a molecular weight of 126. As a result, 126*250/(20*1000) = 1.575 gram of oxalic acid must be dissolved in water in a 250 ml volumetric flask to make a 250 ml M/20 oxalic acid solution.
Ques: How do you prepare a standard solution in chemistry? (2 marks)
Ans: The following is how you can make a standard solution using the weighing approach.
- The required amount of solute is calculated and weighed.
- In a beaker, the solute is dissolved in distilled water.
- Transfer the solution to a volumetric flask.
Ques: How do you prepare a standard solution for acid-base titration? (2 marks)
Ans: An acid with a known concentration (a standard solution) is progressively introduced to a base with an unknown concentration during an acid-base titration (or vice versa). To the base, a few drops of indicator solution are added. When the base has been neutralized (when [H+] Equals [OH-]), the indicator will change color.
Ques: What are standardization and standard solution? (2 marks)
Ans: The process of standardization is used to determine the exact concentration of a solution. Titration is the most often used technique for standardizing a solution. A standard solution is required as a reference in the standardization process.
Ques: What is solution preparation? (2 marks)
Ans: A solution is made by dissolving a known mass of solute (usually a solid) in a given amount of solvent. M or molarity, which is moles of solute per liter of solution, is one of the most frequent ways to express the concentration of a solution.
Ques: What is the standard solution in analytical chemistry? (2 marks)
Ans: A standard solution is a solution that contains a precisely known concentration of an element or compound in analytical chemistry. To make a specific volume, a known mass of solute is dissolved.
Ques: What precautions must be taken while preparing a solution of oxalic acid? (3 marks)
Ans: The precautions that must be taken while preparing a solution of oxalic acid are as follows:
- Place the balance in a room where it will not be affected by small influences.
- Reduce percentage errors by using more accurate equipment.
- Only when the amount of alkali is in proportion to the amount of acid is complete neutralization achievable.
- As a result, the equivalent mass of acid dissolved in volume V1 of solvent should equal the corresponding mass of base dissolved in volume V2 of solvent at the endpoint.
Ques: What are the uses of oxalic acid solution 5%? (2 marks)
Ans: There are several uses for the 5% oxalic acid solution. It is employed as a decalcifier in histology to eliminate calcium deposits from tissue specimens, and as a rust remover and calcium deposit remover in cleaning and surface treatment. samples of tissue oxidation. polishing high-alloy steels electrolytically.
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