Acommon way of initiating certain chemical reactions with light involves the generation of free halogen atoms in solution. if δh for the reaction cl 2(g) → 2cl(g) is 242.8 kj/mol, what is the longest wavelength of light that will produce free chlorine atoms in solution?

493.02 nm is the longest wavelength of light that will produce free chlorine atoms in solution.

Explanation:

,ΔH = 242.8 kJ/mol

Energy required to break 1 mole of Cl-Cl bond = 242.8 kJ

Energy required to break 1 Cl-Cl bond = E

Energy related with the wavelength of light is given by Planck's equation:

493.02 nm is the longest wavelength of light that will produce free chlorine atoms in solution.

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.