##### Chemistry help Please on Molecular Compound

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# The combustion of 135 mg of a hydrocarbon produces 440mg of co2 and 135 mg H20. The molar mass of the...?

hydrocarbon is 270 g/mol. Determine the molecular formula of this compound.

Oct 12th, 2015

moles of co2 = 0,.44g/ 44 = 0.01 moles                    MOLES OF CARBON = 0.01

moles of H20 = 0.135/ 18 = 0.0075 moles              MOLES OF H = 0.0075 * 2 = 0.015

mole ratio   OF          C               TO        H

=                            0.01/0.01                   0.015/0.01

=                                 1  : 1.5

= 2: 3

THE EMPIRICAL FORMULA IS THUS C2H3

To get the molecular formula we multiply the molar mass of the empirical formula by n so as to get the molecular formula

(C2H3)n = 270g/mole

(12* 2 + 3 )n= 270

27n = 270

n = 10

molecular formula is thus

C2H3)*10

=C20 H30

Oct 12th, 2015

Thank you. are the 2 and the 3 subscripts or coefficients?

Oct 12th, 2015

subscripts

Oct 12th, 2015

sorry i understand it now 20 and 30 are the subscripts  of Carbon and Hydrogen. Thank you very much : ) It means a lot

Oct 12th, 2015

Yes they are. Welcome.

Oct 12th, 2015

Oct 12th, 2015

Yes ask it as a new question and invite me as your tutor

Oct 12th, 2015

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Oct 12th, 2015
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Oct 12th, 2015
Sep 24th, 2017
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