why does aluminum foil not get hot
The best way to understand thermodynamics is using an analogue model: an Electrical RC model or a Fluid model. I ll use the later one because it s
much more visual, and everybody has a sink, a drain and a faucet in their kitchens. There are 3 process that should be addressed: heat generation, accumulation and dissipation. While the first is an external factor, the later 2 depend on the material and its shape, respectively. The heat generation doesn t matter right now, all you have to know is that the gas combustion in the oven releases energy in heat form that the oven, and its content absorbs. Just like opening a faucet, you can fill the sink in your kitchen. The accumulation process is related to the material and how much matter you have. The more massive the object the more heat it can accumulate, that part simple. Some other factors can modify the relation since you can have 1 pound of iron and 1 pound of wood, they can t save the same amount, this property of each material is called.
And this in our faucet/sink/drain model would be the sink, the bigger the sink the more water it can hold: logically. The third is dissipation, and this one is related to the shape of the object, specially with it s surface. The object s surface it were it looses all it s excess of heat to the room, when pulled out of the oven. To keep it simple you can say that the bigger the surface of the object the more it can dissipate, hence it will get cooler faster. As you can imagine this would represent the drain in our model. So the wider the drain, the more it flushes! That flush is what you feel as hot when you touch it. So we go back to our thin foil situation: it has very tiny mass and a very large surface. This in our model would be like having a sink the size of a teacup and a drain the size of a sewer! It doesn t matter how much water you put into the sink, as soon as you close the faucet it will drain out before you can feel it. other example : other things that can be explained this way is why can you touch the coal in a fire with a wooden stick without burning your hands.
Would someone like to use this model to answer that?! EDIT: sorry for my English, I m a native Spanish speaker Answer 5: Hmmmm. I don't know what kind of fancy aluminum foil you've been using, Nicole, but aluminum foil gets really hot in my oven. To understand why this happens, it's good to know what "temperature" and "heat" really mean. Everything is made of molecules and atoms, and all atoms are made of a very heavy nucleus with a bunch of small electrons orbiting around it like moons. The temperature of an object tells you how fast the molecules in that object are moving. When something gets really hot, its molecules get moving around really fast. When you heat up a liquid (like water), the liquid molecules start moving so fast that they stop sticking together, and they change from a liquid into a gas (this is what happens when water boils).
The same thing happens when you heat up a solid (like ice) -- the molecules stop sticking together, and the solid melts into a liquid. Most of the things you use every day will melt inside an oven -- think of ice, or glass, or plastic things (please don't try to experiment with melting things in your oven! ). That's because the molecules making up those things are held together pretty weakly. But metals, like aluminum foil, are different. Instead of being made of lots of individual molecules, atoms are one big block of nuclei that all share electrons with each other. You can think of it like this: most materials (like plastic) are like a bunch of grapes -- each nucleus is weakly attached to the others by a tiny little stem. It's easy to cut the stem or knock off a few grapes if you bump into the bunch, and if you shake the bunch, all the grapes move around in different ways.
But the nuclei in metal are more like the grapes in a Jell-O fruit cocktail. They're all linked together by a goop of electrons (the Jell-O), it's tough to get just one grape out without pushing a bunch of the jello around and making a big mess, and if you shake the jello, all the grapes bounce in the same way. So when you heat up a metal, the goop of electrons (physicists call it the 'sea' of electrons) can start getting hot and moving really fast, but all the nuclei stay in the same place and just pass the electrons back and forth amongst themselves. So a metal can get really, really hot before it gets so hot that the nuclei stop sticking together. That's why you can put your aluminum foil in the oven and it will get hot, but you won't be able to turn up the heat enough to melt it. Click to return to the search form.
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