1. Find the molar mass of sodium:

* The molar mass of sodium (Na) is approximately 22.99 g/mol. You can find this on the periodic table.

2. Use the formula:

* mass = moles * molar mass

3. Plug in the values:

* mass = 4.00 moles * 22.99 g/mol

* mass = 91.96 g

Therefore, the mass of 4.00 moles of sodium is 91.96 grams.