A 0.00215-g sample of polystyrene, a polymer composed of carbon and hydrogen, produced 0.00726 g of CO2 and 0.00148 g of H2O in a combustion analysis. What is the empirical formula for polystyrene?

CH

Explanation:

Polystyrene is composed only by C and H.

We can calculate the number of C moles contained in the original sample mass (0.00215 g), using the produced mass of CO₂:

As 1.65x10⁻⁴ moles of CO₂ were produced, in the polystyrene sample there were 1.65x10⁻⁴ moles of C.

Now we calculate how many moles of H₂O were produced:

The number of H moles produced is double the amount of H₂O moles, so in the polystyrene sample there were 1.64x10⁻⁴ moles of H.

The number of C and H moles are the same, this means the empirical formula is CH.

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.