A 48.0-g sample of an element has the same number of atoms as 6.00 g Na. What is the element?

mols Na = 6.00/23 = 0.261

atoms Na = 0.261 mols x (6.02 x 10^23 atoms/mol) = 1.57 x 10^23.

atoms element X = 1.57 x 10^23 (same as Na).
mols X = 1.57 x 10^23 x (1 mol/6.02 x 10^23 atoms) = 0.261
mols = g/atomic mass or rearrange to
atomic mass = g/mol = 48.0/0.261 = ??. Look it up on the periodic table.

To determine the element, we need to compare the number of atoms in a 48.0 g sample of the unknown element with the number of atoms in 6.00 g of sodium (Na).

The first step is to calculate the number of moles of sodium (Na) in the 6.00 g sample using its atomic mass. The atomic mass of sodium is 22.99 g/mol.

Number of moles of Na = mass of Na / atomic mass of Na
Number of moles of Na = 6.00 g / 22.99 g/mol

Now, let's calculate the number of moles of the unknown element using its atomic mass. Since the unknown element has the same number of atoms as 6.00 g of Na, the ratio between the moles of the unknown element and Na will be the same.

Number of moles of unknown element = (Number of moles of Na) * (atomic mass of Na / atomic mass of the unknown element)

Now, we can find the atomic mass of the unknown element using the relation:

atomic mass of the unknown element = (mass of the unknown element) / (Number of moles of the unknown element)

Now, plug in the values to find the atomic mass of the unknown element:

Number of moles of Na = 6.00 g / 22.99 g/mol
Number of moles of unknown element = (Number of moles of Na) * (22.99 g/mol / atomic mass of the unknown element)
atomic mass of the unknown element = (mass of the unknown element) / (Number of moles of the unknown element)

By determining the atomic mass, you can use the periodic table of elements to identify the element that corresponds to that mass.