When ignited, solid ammonium dichromate decomposes in a fiery display. This is the reaction for a "volcano" demonstration. The decomposition produces nitrogen gas, water vapor, and chromium(III) oxide. The temperature is constant at 25°C.

Substance ΔHf° (kJ/mol) S° (kJ/mol K)
Cr2O3(g) –1147 0.08115
H2O(l) –242 0.1187
N2(g) 0 0.1915
(NH4)2Cr2O7(s) –22.5 0.1137

Determine ΔSuniv° (in kJ/mol K).

a) 6.39 b) 7.66 c) 6.03 d) 84.3 e) 5.22

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.