Acell composed of a platinum indicator electrode and a silver-silver chloride reference electrode in a solution containing both fe2+ and fe3+ has a cell potential of 0.727 v. if the silver-silver chloride electrode is replaced with a saturated calomel electrode (sce), what is the new cell potential?

0.683 V

Explanation:

The saturated calomel electrode (SCE) is based on the following reaction:

0.5 Hg₂Cl₂(s) + e⁻ → Hg(l) + Cl⁻

If compared to the Standard Hydrogen Electrode, this electrode has a potential of +0.241 V, while the silver-silver chloride has a potential of +0.197 V.

So the new cell potential would be:

0.727 - (0.241 - 0.197) = 0.683 V

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.