1. Determine the Molar Mass of Bromine:
* Bromine exists as a diatomic molecule (Br₂).
* The atomic mass of bromine (Br) is approximately 79.90 g/mol.
* The molar mass of Br₂ is 2 * 79.90 g/mol = 159.80 g/mol.
2. Calculate the Number of Moles:
* Moles = Mass / Molar Mass
* Moles = 120 g / 159.80 g/mol
* Moles ≈ 0.75 mol
3. Use Avogadro's Number:
* Avogadro's number states that there are 6.022 x 10²³ molecules in one mole of any substance.
* Number of molecules = Moles * Avogadro's number
* Number of molecules ≈ 0.75 mol * 6.022 x 10²³ molecules/mol
* Number of molecules ≈ 4.52 x 10²³ molecules
Therefore, there are approximately 4.52 x 10²³ bromine molecules present in 120 grams of bromine gas.
