Calculate the number of atoms present in each of the following:

• a) 0.5 moles of atoms of nitrogen
• b) 0.2 mol of molecules of nitrogen
• c) 3.2 g of sulphur

To find the number of atoms in each case, we can use Avogadro's number, which is approximately 6.022 x 10²³ atoms per mole. Let's break it down for each part of your question.

Calculating Atoms in Nitrogen

a) 0.5 Moles of Nitrogen Atoms

For 0.5 moles of nitrogen atoms:

• Number of atoms = Moles × Avogadro's number
• Number of atoms = 0.5 moles × 6.022 x 10²³ atoms/mole
• Number of atoms = 3.011 x 10²³ atoms

b) 0.2 Moles of Nitrogen Molecules

For 0.2 moles of nitrogen molecules, each molecule contains 2 nitrogen atoms:

• Number of molecules = 0.2 moles × 6.022 x 10²³ molecules/mole
• Number of molecules = 1.2044 x 10²³ molecules
• Number of atoms = 1.2044 x 10²³ molecules × 2 atoms/molecule
• Number of atoms = 2.4088 x 10²³ atoms

Calculating Atoms in Sulphur

c) 3.2 g of Sulphur

To find the number of atoms in 3.2 grams of sulphur, we first need to convert grams to moles using the molar mass of sulphur, which is approximately 32 g/mol:

• Moles of sulphur = Mass / Molar mass
• Moles of sulphur = 3.2 g / 32 g/mol
• Moles of sulphur = 0.1 moles
• Number of atoms = 0.1 moles × 6.022 x 10²³ atoms/mole
• Number of atoms = 6.022 x 10²² atoms

In summary:

• 0.5 moles of nitrogen atoms = 3.011 x 10²³ atoms
• 0.2 moles of nitrogen molecules = 2.4088 x 10²³ atoms
• 3.2 g of sulphur = 6.022 x 10²² atoms