Oxalic acid (H2C2O4) is a relatively strong organic acid and is a common reducing agent in organic chemistry. There are a number of methods for preparing oxalic acid from nitric acid, and one important difference among them is the amount of oxalic acid that is produced from a given amount of nitric acid. Oxalic acid can be prepared in a laboratory with nothing more than sugar and nitric acid, although a small amount of vanadium pentoxide will act as a catalyst and allow the reaction to proceed much more swiftly.
Things You'll Need
- 100 mL nitric acid
- 20 g cane sugar
- 750 mL flat-bottomed flask
- Bunsen burner
- Drying paper or desiccator
- Evaporating basin
- Filter paper
- Large container to hold boiling water
Place the sugar in the flat-bottomed flask and add the nitric acid. Heat the flask in a bath of boiling water. The sugar will dissolve in a vigorous reaction that produces an extremely large amount of nitric acid fumes.
Remove the flask from the water bath as soon as the reaction begins to produce the fumes, and place it on a surface that will not conduct heat. After the reaction subsides in about 15 minutes, pour the still-hot solution into an evaporating basin.
Evaporate the solution with mild heat from a Bunsen burner for about 15 minutes until it reaches a volume of about 20 mL, then add about 40 mL of water. Evaporate the solution down to about 20 mL again, and thoroughly cool the solution in an ice-water bath.
Allow the rapidly forming crystals of oxalic acid to complete their crystallization in about 10 minutes. Filter the remaining solution through filter paper, and add the crystals to a small amount of hot water. Allow the oxalic acid to recrystallize, which should take about 20 minutes.
Dry the crystals by pressing them between pads of drying paper or with a desiccator. Don't use an ordinary oven since this could cause the oxalic acid to decrystallize. This preparation should yield about 7 g of oxalic acid.
Tips & Warnings
- This method will produce a large amount of nitric acid fumes and must be performed under a fume hood with adequate ventilation.
How to Remove Rust Stains With Oxalic Acid
Depending on the surface that is stained, rust stains can be particularly hard to remove. Concrete and other porous surfaces are more...
How to Dispose of Oxalic Acid Solution
At some point, you may have to use oxalic acid for a cleaning project in your home (it is especially useful for...
How to Use Oxalic Acid (Wood Bleach)
Oxalic acid has many uses, but it is widely used as a wood bleach because it removes stains without removing the natural...
How to Mix Oxalic Acid
Oxalic acid is a naturally occurring compound found in plants such as spinach. In a natural form oxalic acid does not pose...
Oxalic Acid VS Other Deck Cleaners
Redwood and cedar are popular wood choices for decks due to their good looks and long wear. Some deck owners opt to...
Oxalic Acid as a Reducing Agent
Oxalic acid, as the Columbia Encyclopedia, Sixth Edition of 2008 says, is "...useful as a reducing agent for photography, bleaching and ink...
Buying Oxalic Acid
Oxalic acid (C2H2O4) is a chemical compound used for cleaning, bleaching or restoring wood. The substance can kill people in high enough...