Introduction
There are two methods of red P obtaining from match boxes. First method gives dirtier yield while second one allow to obtain much purer product.
Introduction
Ever wondered how safety matches work? Well, never fear, as you will be educated today. The secret to the match comes down to potassium chlorate and red phosphorus. Potassium chlorate (KClO3), a very strong oxidising agent, is the most important ingredient of the match head, often composing around 50% by weight of the match head mixture. Red phosphorus on the other hand, an extremely combustible fuel, is the most important ingredient of the match box red striker pads, also often composing around 50% by weight of the striker pads.
When the match head is run along the striker pad with force, the resulting flame is caused by the formation of a very small amount of the explosive mixture, commonly known as Armstrong’s mixture. It is formed due to a small amount of red phosphorus being removed from the striker pad and mixing with the potassium chlorate. The friction produces enough heat to cause the very heat sensitive Armstrong’s mixture to ignite, leading to a small flame.
As you can tell, matches have some potential for extracting some useful chemicals, but I must crush your expectations. There is such a small amount of each chemical that you can go through multiple match boxes and hardly even get a few grams of crude product. Also, you shouldn’t be interested in the potassium chlorate as it is dangerously oxidising, landing it on the UK regulated substances list as an explosive precursor, requiring an EPP license to have the chemical in your possession.
The other 50% that composes striker pads is mostly glass, to improve friction when striking a match, and adhesives, to hold the striker pad to the box. We will use acetone to remove the adhesives, but we will leave the glass as it shouldn’t affect any reactions we use the red phosphorus in, although when weighing out accurate masses of the red phosphorus the glass will need to be taken into account. Typically, 25% of the red phosphorus mixture will be glass.
When the match head is run along the striker pad with force, the resulting flame is caused by the formation of a very small amount of the explosive mixture, commonly known as Armstrong’s mixture. It is formed due to a small amount of red phosphorus being removed from the striker pad and mixing with the potassium chlorate. The friction produces enough heat to cause the very heat sensitive Armstrong’s mixture to ignite, leading to a small flame.
As you can tell, matches have some potential for extracting some useful chemicals, but I must crush your expectations. There is such a small amount of each chemical that you can go through multiple match boxes and hardly even get a few grams of crude product. Also, you shouldn’t be interested in the potassium chlorate as it is dangerously oxidising, landing it on the UK regulated substances list as an explosive precursor, requiring an EPP license to have the chemical in your possession.
The other 50% that composes striker pads is mostly glass, to improve friction when striking a match, and adhesives, to hold the striker pad to the box. We will use acetone to remove the adhesives, but we will leave the glass as it shouldn’t affect any reactions we use the red phosphorus in, although when weighing out accurate masses of the red phosphorus the glass will need to be taken into account. Typically, 25% of the red phosphorus mixture will be glass.
The white tile features some of the equipment and chemicals I thought I would need as I started the experiment.
Using a pair of scissors, I cut the match boxes to acquire just the cardboard that has a striker pad surface. I scratched the striker pads with a metal spatula to see if the red composition was loose enough to be removed without a solvent, but this was very difficult. I dampened a cotton ball with water and wiped it along the striker pads in the hope to soften them, although the metal spatula was still unable to scrape off the red composition effectively this way.
I had to switch the water out for a different solvent, as I thought might happen, and another cotton ball was dampened with acetone in the hope of removing any adhesives. This seemed to work, but the thin layer of acetone applied evaporated too quickly to be useful. I decided to add a small volume of acetone to a 100 mL glass beaker and soak half a striker pad face-down in the acetone until the cardboard was visibly soaked. I found the red composition of the striker pad to be easily removed in this way.
I then soaked all of the striker pads in this way and then held at a slant towards a receiving container, in my case a 100 mL glass beaker, and I scraped the red composition into the receiving container using a metal spatula. The method worked well, although cardboard from below the surface was occasionally scraped off as well, contaminating the red composition; this was a more frequent event if the striker pads were allowed to dry, so working fast was relatively important. Also, I did not use a large enough receiving container and I ended up with a small loss of the red composition, as it missed the container so I upgraded and transferred everything to a 250 mL beaker.
Once all of the red composition was transferred to the 250 ml beaker, I added a small volume of acetone to cover the red composition and provide a further wash to remove any adhesives. I agitated the red composition with the metal spatula a few times, and then the excess acetone was decanted off. I repeated this process a couple of times, and then I transferred the damp red composition to a few sheets of printing paper and left it to dry.
I had to switch the water out for a different solvent, as I thought might happen, and another cotton ball was dampened with acetone in the hope of removing any adhesives. This seemed to work, but the thin layer of acetone applied evaporated too quickly to be useful. I decided to add a small volume of acetone to a 100 mL glass beaker and soak half a striker pad face-down in the acetone until the cardboard was visibly soaked. I found the red composition of the striker pad to be easily removed in this way.
I then soaked all of the striker pads in this way and then held at a slant towards a receiving container, in my case a 100 mL glass beaker, and I scraped the red composition into the receiving container using a metal spatula. The method worked well, although cardboard from below the surface was occasionally scraped off as well, contaminating the red composition; this was a more frequent event if the striker pads were allowed to dry, so working fast was relatively important. Also, I did not use a large enough receiving container and I ended up with a small loss of the red composition, as it missed the container so I upgraded and transferred everything to a 250 mL beaker.
Once all of the red composition was transferred to the 250 ml beaker, I added a small volume of acetone to cover the red composition and provide a further wash to remove any adhesives. I agitated the red composition with the metal spatula a few times, and then the excess acetone was decanted off. I repeated this process a couple of times, and then I transferred the damp red composition to a few sheets of printing paper and left it to dry.
Results
The dry red composition should now be pure enough to be called red phosphorus in my opinion, although it will still contain various impurities such as cardboard scraped off from the match box. The red phosphorus was transferred to a piece of paper to weigh, giving a yield of a respectful 0.506 g.
This averaged out as a recovery of just over 0.1g per match box as we had used five match boxes, although I suspect one of the two brands I used had significantly more red phosphorus due to larger striker pads. I can see this as a reliable method to extract small amounts of red phosphorus. Other brands of match boxes though may react differently to this method of extraction with acetone and so it may not be viable as some people recommend water to loosen the striker pads instead.
The dry red composition should now be pure enough to be called red phosphorus in my opinion, although it will still contain various impurities such as cardboard scraped off from the match box. The red phosphorus was transferred to a piece of paper to weigh, giving a yield of a respectful 0.506 g.
This averaged out as a recovery of just over 0.1g per match box as we had used five match boxes, although I suspect one of the two brands I used had significantly more red phosphorus due to larger striker pads. I can see this as a reliable method to extract small amounts of red phosphorus. Other brands of match boxes though may react differently to this method of extraction with acetone and so it may not be viable as some people recommend water to loosen the striker pads instead.
Second method
Introduction
I carried out experiments with red phosphorus obtaining from match striker pads, first from 10 boxes, then reached 50. At first, I tried to scrape off this phosphorus mixture with a scalpel, but the yield was very low. I found a very simple way to obtain phosphorus from them with a good yield!
Introduction
I carried out experiments with red phosphorus obtaining from match striker pads, first from 10 boxes, then reached 50. At first, I tried to scrape off this phosphorus mixture with a scalpel, but the yield was very low. I found a very simple way to obtain phosphorus from them with a good yield!
Here is the way. We took match boxes which can be used, and cut off striker pads from them with scissors, put them into a jar of water overnight. We take them out in the morning, and, armed with a knife, remove phosphorus from them with a thin layer of paper; it is simply removed. Half of the striker pad is removed, we also remove the second half in the same way. We cut off the side pieces of paper with scissors and dry.
We take a test tube and a glass cup or beaker, it gets dirty, and you can’t wash it off. For the second experiment, I took 50 boxes (that is, 100 striker pads, and since each striker pad is divided into two parts, there are only 200 pieces). We put all striker pads in a test tube and press it, turn the test tube over and put it in a glass of water (throat down).
We go outside and start heating the test tube with a burner. Phosphorus vapor will condense on the inside of the test tube, which is underwater. Due to the rise in temperature, the air expands and bubbles out of the test tube. Sometimes it takes with it a grain of phosphorus, which, once in the air, immediately catches fire (this can be seen even if the Sun is shining): therefore, the experiment cannot be carried out at home (or rather, it can be done under hood).
We put our glass with a test tube (do not pull out the test tube!) in a water bath. When the water warms up, we start to shake the test tube, soon all the large drops of phosphorus will flow down, but the smaller ones will not come off (then they can be dissolved in gasoline and used for experiments). Now you can get a test tube.
If you take ten boxes at a time (or rather, twenty striker pads), then a piece of phosphorus will be the size of half a small pea [there is no quantitative yield, sorry].
If you take fifty boxes, a piece of phosphorus will not be two and a half small peas (as you thought), but less: the fact is that the phosphorus, which is at the very top, remains in the charred striker pads. Here, on the left, a piece obtained from 10 boxes, and on the right from 50.
If you take fifty boxes, a piece of phosphorus will not be two and a half small peas (as you thought), but less: the fact is that the phosphorus, which is at the very top, remains in the charred striker pads. Here, on the left, a piece obtained from 10 boxes, and on the right from 50.
I think that it is optimal to use a load of about 25 - 30 boxes (50 - 60 striker pads). For the experience described, I took about 10 - 15 used (striker pads) boxes, and 35 - 40 not used. From used striker pads, the yield of phosphorus will be half as much.
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