| Learning Aims: |
- The described procedure of preparation of “nitro” cotton wool - nitrocellulose can be dangerous. The synthesis should be done by experienced chemists and if you decide to prepare it, you do it on your risk. You have to follow exactly the described procedure and all the weight and amounts of chemical used for synthesis!!! Prepared nitrated cotton wool keep on safe places and avoid any sources of heat and flame.
Prepared nitrated cotton wool – nitrocellulose - is flammable and/or explosive!!!!!
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| Materials: |
- Bigger beaker,
- smaller beaker,
- cotton wool,
- huge amount of ice,
- concentrated sulfuric acid,
- concentrated nitric acid,
- beaker with cold water,
- rubber gloves and glasses (wear them during all the synthesis).
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| Suggestions for use: |
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Procedure:
- Pour 25 mL of concentrated nitric acid and 45 mL of concentrated sulphuric acid into a smaller beaker immersed into a bigger beaker filed with ice.
- After the reaction mixture reach 10 °C, put (in more small pieces) 2 g of cotton wool. It must be immersed in mixture. We can move the pieces of cotton wool using glass rod. Nevertheless, do not rub or tap with it to avoid ignition of the mixture.
- Left the immersed cotton wool in mixture for 60-90 minutes (smaller beaker is must be still immersed in ice bath). Empty the reaction mixture and tip the cotton wool into a beaker with cold water. Tear the cotton wool to pieces in the water to remove all the traces of acids used during synthesis. Repeat the wash procedure with cold water 3 times, always with cold pure water.
- Neutralize 3 times the cotton wool pieces by washing in 5 % solution of Na2CO3. This step is really important. If you skip it, the nitrocellulose is unstable and explosive.
- Repeat the wash procedure with cold water 3 times, always with cold pure water.
- Finally, wash and wring the cotton wool out in ethanol. Then, tear the cotton wool to pieces and put them on filtration paper. Let the pieces of cotton wool to dry on air. Avoid any sources of heat and flame near the filtration paper with nitrocelulose. Do not dry the nitrocellulose in drying machnes or on flame!!!!!
- Keep the nitrocellulose at dry conditions in dark place in plastic bottle. Avoid any sources of heat and flame. Never use for keeping glass of metal cases!!!
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