Mercury can be obtained by reacting mercury(ii) sulfide with calcium oxide. how many grams of calcium oxide are needed to produce 31.28 g of hg?

Explanation:

First we have to start with the reaction:

The next step is to balance the reaction, we can start with Oxygen, so:

Then we can continue with Ca:

Then we can balance S:

And finally with Hg:

With the balance reaction we know that the molar ratio between Hg nd CaO is 4:4. Therefore, the nex step is the conversion of 31.28 g Hg to moles of Hg using the atomic mass of Hg (200.59 g/mol).

The next step, using the molar ratio (4:4) and the molar mass of CaO (56.1 g/mol) we can calculate the grams of CaO that we need:

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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.