AP Chemistry

C2H2(g) + 2H2(g) --> C2H6(g)

Information about the substances involved in the reaction represented above is summarized in the following table:

C2H2(g) 226.7 kj/mol
C2H6(g) -84.7 kj/mol
[the values are the change in enthalpy]

a. write the equation for the heat formation of C2H6.
b. Use the above information to determine the enthalpy of reaction for the equation given.


A, for some reason, is throwing me off. I don't know what it's asking. Help?


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  1. Do part b first.
    delta Hrxn = (delta H products) - (delta H reactants)

    Then write the equation and add heat to the left side or to the right side depending upon the sign of delta Hrxn. I think that will be negative; therefore,
    C2H2(g) + 2H2(g) --> C2H6(g) + heat

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  2. Ffg

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