Question

What is the mass in grams of `4.6*10^21` molecules of carbon tetrabromide?

Answer 1

`(4.6xx10^21" molecules")/(6.022xx10^23" molecules mol"^-1)xx331.61*g*mol^-1` `=` `??` `g`

Explanation:

`6.022xx10^23` molecules, i.e. a mole, of `CBr_4`, have a mass of `331.61*g`.

So the mass of your given number of molecules is:

`(4.6xx10^21*"molecules")/(6.022xx10^23*"molecules"*"mol"^-1)xx331.61*g*mol^-1=?*g`.