The empirical formula for ethane is ch3.the molar mass of propane is 30.08 grams per mole. determine the molecular formula of ethane.

The molar formula of a compound can be obtained from the given molar mass and the empirical formula of the compound. In this case, the molar mass is 30.08 grams and the empirical formula is CH3. The molecular mass of CH3 is 15.04 grams. We divide the molar mass to 15.04, the answer is 2. Hence the molecular formula is C2H6. 

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.