Question

Question #7a65a

Answer 1

Given that `1.41xx10^22` molecules of Styrene weigh `2.44g`.We can write 1 mol or `6.03xx29^23`molecules of Styrene will weigh

`(2.44xx6.023xx10^23)/(1.41xx10^22)g~~104g`

`"Hence molar mass of Styrene"=104g/"mol"`

Now dividing given percentage composition C and H with their respective atomic masses we can have
`"The ratio of number of C and H atom in its"`
`"molecule"=C:H=92.26/12:7.74/1`
`=7.69:7.74~~1:1`

`"Hence empirical formula of Styrene"=CH`

`"Let its moleculr formula"=(CH)_n`

`"So its molar mass from its MF becomes"`
`=(12+1)n=13ng/"mol"`

Hence we can write

`13n=104=>n=8`

`"So the molecular formula of Styrene"`

`=C_8H_8`

Answer 2

First step:
To find out the empirical formula of Styrene we divide the given percentages of its components by respective Average atomic masses.
`"Carbon":"Hydrogen"=92.26/12.011:7.74/1.0079`
`=>"Carbon":"Hydrogen"=7.68:7.68`
`=>"Carbon":"Hydrogen"=1:1`
We obtain Empirical formula of Styrene as `"CH"`
As such molecular formula is `"C"_n"H"_n`

Second Step:

To find `n` number of atoms in each molecule we use Avogadro's number `6.023xx10^23`
We know that `6.023xx10^23` molecules of any substance are equal to its `1`gm mole.
It is given that `1.41xx10^22` molecules weigh`=2.44g`
`:.` weight of `6.023xx10^23` molecules `=2.44/(1.41xx10^22)xx6.023xx10^23`
`=104.22g`
Now weight of `"CH"=12.011+1.0079=13.0189`
`:.n=104.22/13.0189=8.005`
This gives us molecular formula of Styrene as `"C"_8"H"_8`
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Styrene is also known as ethenylbenzene, vinylbenzene, and phenylethene. It is an organic compound and its chemical formula is `"C"_6"H"_5"CH=CH"_2`