Question

How many atoms of H is in 4.20 mols of C2H6

Answer 1

One Ethane ( $C_2H_6$ ) molecule has 6 H atoms

1 Mole of $C_2H_6$ = Gram Molecular Weight of $C_2H_6$

= (2 x 12) + (6 x 1)

= 30 g

mass of $C_2H_6=30\times4.2=126g$

We know that 1 Mole of $C_2H_6$ has Avogadro number of Molecules

Avogadro number = 6.023 x10^{​​​​23}

But here he is asking about number of H atoms. So,

1 Mole $C_2H_6$ has (6 x 6.023 x10^{​​​​23} ) H atoms

30 g of C2H6 has ( 6 x 6.023 x 10²³ ) H atoms

126 g of C2H6 has ? H atoms

= 126 g x (6 x 6.023 x 10²³) H atoms $/$ 30 g=$1.52\times 10^{25} atoms$