Question

) Find out the mass of
a) 6.023× 1023 number of O2 molecule.
b) 1.5 moles of H2O molecule

Answer 1

6.023*$10^{23}$  $O_2$ molecules are equal to 32 gms and 1.5 moles $H_2O$ is equal to 27 gms.

Explanation:

a) 6.023*$10^{23}$ $O_2$ molecules

Avadagro's Number i.e. 6.023*$10^{23}$ of any element/compound is equal to 1 mole of that element/compound.

If, 6.023*$10^{23}$ $O_2$ molecules are present; it implies that 1 mole of $O_2$

To find the mass of 1 mole  $O_2$, we use

[tex]Moles = \frac{Mass}{Molecular\ mass} \\ [/tex]

Molecular mass of $O_2$ = $32 gm\ mole^{-1}$

Substituting;

$1 = \frac{Mass}{32}$

$Mass = 32\ gms$

b) 1.5 moles of $H_2O$

$Moles = \frac{Mass}{Molecular\ mass}$

Molecular weight of $H_2O$ = $18 gm\ mole^{-1}$

Substituting;

[tex]1.5 = \frac{Mass}{18} \\ Mass = 1.5 * 18\\ Mass = 27\ gms[/tex]