Question

PLEASE HELP ME what would be the mass of 9.03 x 1021 molecules of hydrobromic acid (HBr)?

Answer 1

We know 1 mole of any atom or molecules contains $6.033 \times 10^{23}$ atom or molecules.

1 mole of HBr i.e 81 gm/mol contains  $6.033 \times 10^{23}$ atom or molecules.

So, mass of $9.03\times 10^{21}$ molecules is :

$m=\dfrac{81\times 9.03\times 10^{21} }{6.033 \times 10^{23}}\\\\m= 1.21\ gm$

Therefore, mass of  $9.03\times 10^{21}$ molecules is 1.21 gm .

Hence, this is the required solution.