Final answer:
To determine the mass in grams of 2.79 × 10²¹ atoms of arsenic, convert the atoms to moles using Avogadro's number and multiply by the molar mass of arsenic. The mass is approximately 0.346 grams.
Step-by-step explanation:
To determine the mass in grams of 2.79 × 10²¹ atoms of arsenic, we need to use the molar mass of arsenic and convert the given amount of atoms to moles using Avogadro's number. The molar mass of arsenic is 74.92 g/mol.
First, calculate the number of moles of arsenic:
Moles of arsenic = (2.79 × 10²¹ atoms) / (6.022 × 10²³ atoms/mol) = 4.62 × 10⁻³ mol
Next, convert moles to grams:
Mass in grams = (4.62 × 10⁻³ mol) × (74.92 g/mol) = 0.346 g
Therefore, the mass of 2.79 × 10²¹ atoms of arsenic is approximately 0.346 grams.