A chemist weighed out 84.9 of sodium. Calculate the number of moles of sodium she weighed out.

mols = grams/atomic mass.

To calculate the number of moles of sodium, we need to use the molar mass of sodium. The molar mass of an element is the mass of one mole of that element and is given in grams per mole.

The atomic mass of sodium (Na) is approximately 22.99 g/mol.

Now, we can calculate the number of moles using the formula:

Number of moles = Mass of substance / Molar mass

Plugging in the values, we have:

Number of moles = 84.9 g / 22.99 g/mol

Dividing these values, we get:

Number of moles ≈ 3.69 mol

So, the chemist weighed out approximately 3.69 moles of sodium.