Question

Sand is made up of silicon dioxide, SiO2 (molar mass=60.). How many silicon atoms are in a

smgle grain of sand weighing 55.2 micrograms?

Answer 1

5.54 × 10¹⁷ atoms

Step-by-step explanation:

Given data:

Mass of sand = 55.2 μg (55.2 ×10⁻⁶ g)

Molar mass of sand = 60 g/mol

Number of atoms = ?

Solution:

Number of moles = mass/ molar mass

Number of moles = 55.2 ×10⁻⁶ g / 60 g/mol

Number of moles = 0.92 × 10⁻⁶ mol

Number of atoms:

one mole = 6.022 × 10²³ atoms

0.92 × 10⁻⁶ mol × 6.022 × 10²³ atoms / 1mol

5.54 × 10¹⁷ atoms