1. Understand the Formula

* Na₂SO₄ represents sodium sulfate. The subscript "2" next to Na indicates that there are two sodium atoms in each molecule of sodium sulfate.

2. Use Avogadro's Number

* Avogadro's number tells us there are 6.022 x 10²³ particles (atoms, molecules, etc.) in one mole of a substance.

3. Set up the Calculation

* We need to find the number of sodium atoms in 0.250 moles of Na₂SO₄.

* We'll use the following steps:

* Moles of Na₂SO₄ -> Moles of Na: Since there are two sodium atoms per molecule of Na₂SO₄, multiply the moles of Na₂SO₄ by 2.

* Moles of Na -> Number of Na atoms: Use Avogadro's number to convert moles of Na to the number of atoms.

Calculation:

* Moles of Na: 0.250 moles Na₂SO₄ * (2 moles Na / 1 mole Na₂SO₄) = 0.500 moles Na

* Number of Na atoms: 0.500 moles Na * (6.022 x 10²³ atoms Na / 1 mole Na) = 3.011 x 10²³ atoms Na

Answer: There are approximately 3.011 x 10²³ atoms of sodium in 0.250 moles of Na₂SO₄.