How many molecules are in 3.40 mol he?

20.5 × 10²³ molecules of He

Explanation:

Given data:

Number of moles of He = 3.40 mol

Number of molecules of He = ?

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 3.40 moles of He:

3.40 mol × 6.022 × 10²³ molecules

20.5 × 10²³ molecules of He