yello said:
No, actually I didn't do chemistry at college. Sorry about that. So would someone that did like to tell me how stable potassium gets into a banana in the first place then, and at what point? And why do bananas get a different quantity to, say, apples? Or is that biology? Didn't do that either.
Seriously though, I asked a genuine question. I don't take kindly to being addressed as an idiot simply because I ask about something. Even if there is a smiley stuck on the end.
Sorry - I was trying to be humorous but not at you or anybody else's expense - I apologise for any offence caused.
I know lots of people who did chemistry and often fell asleep because they found it really boring.
The point I was making about potassium is that it isn't stable as it is. It is desperate to react with other elements and by the time it ends up in a banana it already has done.
I mentioned hydrogen and oxygen reacting together to create water. There is actually oxygen in the atmosphere which is what we breathe but there isn't a lot of hydrogen just floating around up there as well - all of it has already reacted with oxygen to make our water. If there had been enough hydrogen to go around then all of the oxygen would have been used up and there would be a lot more water on the planet, but no form of life that needed oxygen (I think they all do, but there might be some sort of tiny microbe that doesn't - I didn't do biology at school for long so I don't know).
You can reverse the process and separate water into hydrogen and oxygen but it takes a lot of energy to do it. That energy would be released again if you combined the gases and lit them. The heat from a match would start a violent reaction and that would continue until the two gases had reacted together again. It would all be over in a very short time. That's what happened in the
Hindenberg Disaster. The airship was full of hydrogen gas and something must have ruptured one of the gas bags to let the oxygen in the atmosphere mix with the hydrogen to make an explosive mixture.
Potassium isn't available in nature as a pure element exactly because it is so reactive. It has had billions of years to find something to react with. Banana plants just pick it up from the soil in compounds made with other elements.
Any potassium that now exists in a pure form is only like that because it has been purified by chemical engineers using some means involving enough energy to shatter the chemical bonds that hold its compounds together. It wouldn't stay pure like that unless it was kept away from everything that it can react with. I can't remember if it reacts with oxygen from the air. If it it does then you couldn't just keep it in a glass jar. You certainly couldn't let water get near it.
Gold on the other hand is so unreactive that it is literally just lying around in places waiting to be found.
Some substances are fairly reactive but not violently so. Coal for example. That is made up of the element Carbon. As we know, coal can be found lying around in the ground so it isn't super-reactive or it would have reacted already, but we also know that it isn't that hard to burn coal. If you burn it in plenty of oxygen you get carbon dioxide which is one of the greenhouse gases that scientists are worried about. There is an awful lot of coal left to be burned which will produce an awful lot of carbon dioxide with potentially dangerous implications for our planet.
As for why there is more of one thing or another in different plants, yes that's something for the biologists. Plants can get water, and carbon dioxide (maybe nitrogen too?) but everything else has to come from the soil. If you are growing bananas, there must be enough potassium in the soil or they wouldn't be able to find it. They can't create it themselves.
If you try to grow the same crop in the same soil year after year, eventually the substances that the particular crop need will start to be be used up unless you replace them with something like fertiliser. Another way of replenishing the soil is
crop rotation. Farmers grow one crop for a while and then switch to a different one which replaces some of the things that the previous crop used up. For example some plants restore nitrogen that others use up.
Anyway, I think I'll stop this now. I didn't mean to come across as a smart-arse, I just thought that people who didn't know this stuff might find it interesting and be tempted to go and read a bit more about it.