Please help?

A form of Arrhenius equation : ln(k₁/k₂) = (Eₐ/R)[(1/T₂) - (1/T₁)]

At T = 400 K and 450 K: ln[(1.25 × 10⁻²)/0.868] = (Eₐ/8.314)[(1/450) - (1/400)] …… {1}
At T = 425 K and 450 K: ln(k/0.868) = (Eₐ/8.314)[(1/450) - (1/425)] …… {2}

From {1} :
Eₐ = 8.314 ln[(1.25 × 10⁻²)/0.868] / [(1/450) - (1/400)]
Eₐ = 126900 (J/mol)

Substitute the value of Eₐ into {2} :
ln(k/0.868) = (126900/8.314)[(1/450) - (1/425)]
ln(k) = (126900/8.314)[(1/450) - (1/425)] + ln(0.868)
k = e^{(126900/8.314)[(1/450) - (1/425)] + ln(0.868)}
k at 425 K = 0.118 /s


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Alternatively :

A form of Arrhenius equation : log(k₁/k₂) = [Eₐ/(2.303R)][(1/T₂) - (1/T₁)]

At T = 400 K and 450 K: log[(1.25 × 10⁻²)/0.868] = [Eₐ/(2.303*8.314)][(1/450) - (1/400)] …… {1}
At T = 425 K and 450 K: log(k/0.868) = [Eₐ/(2.303*8.314)][(1/450) - (1/425)] …… {2}

From {1} :
Eₐ = 2.303 * 8.314 log[(1.25 × 10⁻²)/0.868] / [(1/450) - (1/400)]
Eₐ = 126900 (J/mol)

Substitute the value of Eₐ into {2} :
log(k/0.868) = [126900/(2.303*8.314)] [(1/450) - (1/425)]
log(k) = [126900/(2.303*8.314)] [(1/450) - (1/425)] + log(0.868)
k = 10^{[126900/(2.303*8.314)] [(1/450) - (1/425)] + log(0.868)}
k at 425 K = 0.118 /s