Fortunately no such nightmare threatens us.

    There is a magic barrier which stands in the way of such a universal "chemical catastrophe." 

    This barrier is known as activation energy. Molecules cannot enter into chemical reactions unless their energy equals or exceeds their activation energy. 

    Even at ordinary temperature there will be molecules, among those, say, of hydrogen and oxygen, with energies greater than or at least equal to their activation energy. 

    That is why water forms, though very slowly, under such conditions. The reaction is slow because the number of sufficiently energetic molecules is too small. 

    But a high temperature brings many molecules up to the activation barrier, and the number of instances of chemical interaction between hydrogen and oxygen grows enormously.
 

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