Find the mass of calcium oxide produced from the thermal decomposition of 50 g of calcium carbonate. [Ca=40, C=12, O=16]

28 g

Explanation:

The chemical equation of the reaction is given below:

CaCO₃ (s) ⇒ CaO (s) + O₂ (g)

From the chemical equation, 1 mole of CaCO₃ produces 1 mole of CaO.

So, we find the number of moles,n of  CaCO₃ in 50 g from

n = m/M where n = number of moles of  CaCO₃, m = mass of CaCO₃ and M = molar mass of CaCO₃ = 40 g/mol + 12 g/mol + 3 × 16 g/mol = 52 g/mol + 48 g/mol = 100 g/mol

So, n = m/M

= 50 g/100 g/mol

= 0.5 mol

Since From the chemical equation, 1 mole of CaCO₃ produces 1 mole of CaO, then 0.5 × 1 mole of CaCO₃ produces 0.5 × 1 mole of CaO, which is 0.5 mole of CaCO₃ produces 0.5 mole of CaO.

So, we have 0.5 mol of CaO.

We find the mass of CaO from

n =m'/M' where n = number of moles of CaO = 0.5, m' = mass of CaO and M' = molar mass of CaO = 40 g/mol + 16 g/mol = 56 g/mol

So, m' = nM'

= 0.5 mol × 56 g/mol

= 28 g

3

explanation:

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.