To determine the number of atoms in a given sample, you need to use Avogadro's number, which is approximately 6.022 × 10^23 atoms/mol.
Let's break down the compound Ca(NO3)2:
Ca(NO3)2 indicates that there is one calcium (Ca) atom and two nitrate (NO3) ions in the compound.
The nitrate ion (NO3-) consists of one nitrogen (N) atom and three oxygen (O) atoms.
So, in one formula unit of Ca(NO3)2, we have:
1 Ca atom + 2 (1 N atom + 3 O atoms)
This gives us:
1 Ca atom + 2 (1 N atom + 3 O atoms) = 1 Ca atom + 2 N atoms + 6 O atoms
To find the number of atoms in a 0.50 mole sample of Ca(NO3)2, we need to multiply the number of moles by Avogadro's number:
0.50 mole x (6.022 × 10^23 atoms/mole) = 3.011 × 10^23 atoms
Therefore, a 0.50 mole sample of Ca(NO3)2 contains approximately 3.011 × 10^23 atoms.