Determine the number of molecules contained in 1 mole of sodium sulfate

                      6.022 × 10²³ Molecules of Na₂SO₄

Explanation:

                    Mole is an amount unit. One mole of any substance contains exactly 6.022 × 10²³ particles which is also called as Avogadro's Number. So in order to calculate the number of molecules contained by 1 mole (incase if the moles given are not 1 then following method is used) of Na₂SO₄, we will use following relation,

          Moles  =  Number of Molecules ÷ 6.022 × 10²³ Molecules.mol⁻¹

Solving for Number of Molecules,

          Number of Molecules  =  Moles × 6.022 × 10²³ Molecules.mol⁻¹

Putting values,

          Number of Molecules  =  1.0 mol × 6.022 × 10²³ Molecules.mol⁻¹

          Number of Molecules  = 6.022 × 10²³ Molecules of Na₂SO₄

Hence,

          There are 6.022 × 10²³ Molecules present in 0.280 moles of Br₂.