I need to calculate the number of molecules present in:
(a) 0.650 mol propane, C3H8, a gas used in laboratories
(b) a 500mg tablet of CaCO3, an antacid
There are 6.022x10^23 molecules of "chemical X" in a mole of "chemical X" (in this case "chemical X" is propane).
"Mole" is just a number.
you have 0.650 mol of propane times 6.022x10^23 molecules per mole
= 3.91x10^23 molecules
For the next one, you need to convert ...
The solution talks through the problem by way of explaining how to determine the number of molecules present in the two given samples.