Idézet: FriendlyCheese - 2011.03.28. 17:46:41 Which one is a chemical change?
melting ice
chopping onions
boiling alcohol
exploding a fire cracker <--- marked as correct
boiling alcohol AND exploding a fire cracker both involve chemical change! 100% alcohol might be sligtly different but still a change!
"In a chemical change, bonds are broken and formed between different atoms."(1)
"A chemical bond is an attraction between atoms"(2)
In the first, second and third answer bonds between molecules are broken, such a change is usually refereed to as a change of state or physical change (3).
While it isn´t always easy to differentiate between a physical and chemical change, I would say that the processes in the question are clearly one or the other.
And this is actually not my question.
1) http://en.wikipedia.org/wiki/Chemical_change
2) http://en.wikipedia.org/wiki/Chemical_bond
3) http://en.wikipedia.org/wiki/Physical_change