1. Determine the formula of copper(II) nitrate:
* Copper(II) has a +2 charge (Cu²⁺).
* Nitrate has a -1 charge (NO₃⁻).
* To balance the charges, we need two nitrate ions for every copper(II) ion. The formula is Cu(NO₃)₂.
2. Calculate the molar mass of copper(II) nitrate:
* Cu: 63.55 g/mol
* N: 14.01 g/mol (x2 because there are two nitrogen atoms)
* O: 16.00 g/mol (x6 because there are six oxygen atoms)
* Molar mass = 63.55 + (14.01 x 2) + (16.00 x 6) = 187.57 g/mol
3. Calculate the number of moles of copper(II) nitrate:
* Moles = mass / molar mass
* Moles = 10.2 g / 187.57 g/mol = 0.0544 mol
4. Calculate the number of moles of nitrogen atoms:
* Since there are two nitrogen atoms per formula unit of copper(II) nitrate, there are twice as many moles of nitrogen atoms as moles of copper(II) nitrate.
* Moles of nitrogen = 0.0544 mol Cu(NO₃)₂ * 2 mol N / 1 mol Cu(NO₃)₂ = 0.1088 mol N
5. Calculate the number of nitrogen atoms:
* Use Avogadro's number (6.022 x 10²³ atoms/mol) to convert moles to atoms.
* Number of nitrogen atoms = 0.1088 mol N * 6.022 x 10²³ atoms/mol = 6.55 x 10²² atoms
Therefore, there are approximately 6.55 x 10²² nitrogen atoms in 10.2 g of copper(II) nitrate.
