Final answer:
There are approximately 0.333 millimoles (0.333 x 10^-3 moles) and 2.01 x 10^20 atoms of astatine in the specified portion of Earth's crust.
Step-by-step explanation:
The amount of astatine in the crust of the Earth can be converted to moles and atoms using Avogadro's number, which is 6.022 x 1023 particles per mole. To find the number of moles of astatine in 70mg, we use the formula:
moles = mass (in grams) ÷ molar mass (in grams per mole).
The molar mass of astatine (At) is approximately 210 g/mol (this is a common average value; the actual molar mass can differ slightly based on isotopic composition). Calculating the moles of astatine:
moles = 70 x 10-3 g ÷ 210 g/mol ≈ 0.333 x 10-3 mol.
To calculate the number of atoms, we multiply the number of moles by Avogadro's number:
atoms = moles x Avogadro's number
atoms = 0.333 x 10-3 mol x 6.022 x 1023 mol-1 ≈ 2.01 x 1020 atoms.
Therefore, there are approximately 0.333 millimoles (or 0.333 x 10-3 moles) and roughly 2.01 x 1020 atoms of astatine in the outermost 1 mile of Earth's crust.