Joy asked in Science & MathematicsChemistry · 10 months ago

Need help finding magnitude of K.?

A particular first-order reaction has a rate constant of 1.35x10^2s−1 at 25.0∘C . What is the magnitude of k at 41.0∘ C  if  Ea = 55.5 kJ/mol .

Options:

1.23×10^4  

1.35×10^2  

154  

2.60×10^47  

4.23×10^2 

Thanks in advance!

1 Answer

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  • Dr W
    Lv 7
    10 months ago
    Favourite answer

    from the arrhenius equation

    .. k = Ao exp(-Ea / RT)

    for 2 conditions of different T with Ea held constant

    .. k1 = Ao exp(-Ea / RT1)

    .. k2 = Ao exp(-Ea / RT2)

    dividing the 2nd by the first

    .. k2 / k1 = (Ao / Ao) * exp(-Ea / RT2) / exp(-Ea / RT1)

    rearranging

    .. k2 = k1 * exp[ (Ea/R) * (1/T1 - 1/T2) ]

    where

    .. k1 = 1.35x10^2 / sec

    .. Ea = 55500 J/mol

    .. R = 8.314 J/molK

    .. T1 = 298.15K

    .. T2 = 314.15K

    you get to finish

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