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Construct equation for hydrogenation of beta carotene. watch

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    Beta carotene has 40 carbons and two rings in it's unsaturated structure and is such that 5.98 dm^3 of hydrogen gas reacts with 0.0200mol of Betacarotene at RTP.
    Construct a balanced equation for this reaction.

    I have just sat the mock exam and are not 100% on the wording etc. but I'm sure this is from june 2017
    From what I understand the answer is
    C40H56 + 11H2 --> C40H78.
    And I get how to determine 11mol H2: 1 mol beta carotene
    however how can I deduce the formula for beta carotene? based on the information given in the question.
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    (Original post by ReubenOrion)
    Beta carotene has 40 carbons and two rings in it's unsaturated structure and is such that 5.98 dm^3 of hydrogen gas reacts with 0.0200mol of Betacarotene at RTP.
    Construct a balanced equation for this reaction.

    I have just sat the mock exam and are not 100% on the wording etc. but I'm sure this is from june 2017
    From what I understand the answer is
    C40H56 + 11H2 --> C40H78.
    And I get how to determine 11mol H2: 1 mol beta carotene
    however how can I deduce the formula for beta carotene? based on the information given in the question.
    hydrogenation results in a saturated hydrocarbon, which must have the formula CnH2n+2

    However with two rings you lose four hydrogen atoms therefore the product has the formula:

    C40H78

    Now you use the moles of hydrogen to find out how many double bonds were hydrogenated and work backwards to the formula of beta carotene
 
 
 

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