(oh no)
What is the mass of silicon when there are 1.8 x 10^21 atoms of silicon?

Mass = 0.084 g

Explanation:

Given data:

Mass of silicon = ?

Number of atoms of silicon = 1.8 × 10²¹ atom

Solution:

Avogadro number:

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.  The number 6.022 × 10²³ is called Avogadro number.

1 mole = 6.022 × 10²³  atoms

1.8 × 10²¹ atom × 1 mole /  6.022 × 10²³  atoms

0.299× 10⁻² mol

0.00299 mol

Mass of silicon:

Mass = number of moles × molar mass

Mass = 0.00299 mol × 28.1 g/mol

Mass = 0.084 g