CBSE Class 12 Chemistry 2018 Solved Paper

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Question : 13
Total: 26
A first order reaction is 50% completed in 40 minutes at 300K and in 20 minutes at 320K. Calculate the activation energy of the reaction.
‌‌ (Given : ‌log‌2=0.3010,log‌4=0.6021, R=8.314‌JK−1mol−1‌ ) ‌
Solution:  
‌k2=0.693∕20‌, ‌
‌k1=0.693∕40
‌log‌
k2
k1
=‌
Ea
2.303R
[‌
1
T1
−‌
1
T2
]

‌k2∕k1=2
‌log‌2=‌
Ea
2.303×8.314
[‌
320−300
320×300
]

‌Ea=27663.8J∕mol‌ or ‌27.66‌kJ∕mol
‌
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