If you Increase or decrease temperature and change states of matter, that's a physical change. But are there any circumstances where temperature can cause a chemical change? Like if increasing temperature could break the bonds between the atoms and separate them? And I don't mean a combustion reaction. I'm talking about just temperature change. And if temperature can cause chemical change, then what if you heat H2O to really high temperatures? Like super high temperatures, would it break up into H2 and O2?