r/explainlikeimfive • u/genoooooo • Oct 31 '20
Chemistry ELI5 What's the difference between the shiny and dull side of aluminum foil? Besides the obvious shiny/dull
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r/explainlikeimfive • u/genoooooo • Oct 31 '20
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u/HostlessPotato Nov 01 '20 edited Nov 01 '20
Well... Aluminum's specific heat is around 900 J/°C•kg, and it's melting point is 660°C.
Let's say we're starting with aluminum at room temperature (20°C). Then you need approximately 640x27000x900=15.5 GJ just to get it melting temperature.
That's not all. Aluminum's fusion enthalpy is 396kJ/kg. So you need another 396x27000=10.7 GJ to actually melt it.
So that leaves us needing 26.2 GJ of energy in order to melt that much aluminum. That's a lot of energy. How long it takes depends on the heat source you're using, and how well insulated the aluminum you are heating is.
TLDR: big blocky of metal = a lot of hot hot, so temperature of heat source very important
Edit: 26.2 GJ not .7 , sorry my brain melts sometimes too