How many oxygen atoms in a 300*g mass of calcium carbonate?

1 Answer
Jun 8, 2016

We work out (i) the molar quantity of CaCO_3, and (ii) the constituent quantity of oxygen.

Explanation:

"Moles of calcium carbonate, "(300*g)/(100.09*g*mol^-1) ~= 3*mol.

Given the elemental makeup, in such a quantity there are 3 moles of calcium, 3 moles of carbon, and 9 moles of oxygen.

But what is a mole? It is simply a LARGE number that relates to a given mass of stuff. In 1 mol of stuff there are 6.022xx10^23 individual particles of that stuff.

So given 3 moles of calcium carbonate, there are 3 moles of calcium, 3 moles ofcarbon, and 9 moles of oxygen atoms.

So "number of oxygen atoms" = 9*molxxN_A

= 6.022xx10^23*mol^-1xx9*mol" oxygen atoms" = "oxygen atoms"??

What is the mass of this quantity of oxygen atoms, and how do you know?

See here for another examples of this process.