Question

What is the total number of molecules in a 0.5-mole sample of the He gas?

Answer 1

Avogadro’s constant tells us the number of atoms in a mole of any substance: 6.022x10^23. A mole of water, oxygen, sodium - they all have this many atoms in a 1 mole sample.

A 0.5 mole sample of helium gas would contain 0.5 x (6.022 x 10^23) atoms, or 3.011 x 10^23 atoms. Still a big amount.

Answer 2

Answer : The total number of molecules in 0.5 mole of sample of He gas are,
`3.011* 10^(23)`

Explanation : Given,

Moles of sample of He gas = 0.5 mole

As we know that,

1 mole of gas contains
`6.022* 10^(23)` number of molecules of gas

As, 1 mole of He gas contains
`6.022* 10^(23)` number of molecules of He gas

So, 0.5 mole of He gas contains
`0.5* (6.022* 10^(23))=3.011* 10^(23)` number of molecules of He gas

Therefore, the total number of molecules in 0.5 mole of sample of He gas are,
`3.011* 10^(23)`