Question #7a65a

2 Answers
Aug 31, 2016

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#

Sep 1, 2016

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#