5.40 g B

how many atoms

3 * 10²³ atoms

Explanation:

Given dа ta:

Mass of B = 5.40 g

Number of atoms = ?

Solution:

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.

For example,

18 g of water = 1 mole = 6.022 * 10²³ molecules of water

1.008 g of hydrogen = 1 mole = 6.022 * 10²³ atoms of hydrogen

For 5.40 g of B:

Number of moles = mass / molar mass

Number of moles = 5.40 g / 10.811 g/mol

Number of moles = 0.5 mol

one mole = 6.022 * 10²³ atoms

0.5 * 6.022 * 10²³ atoms

3 * 10²³ atoms