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Chemistry Class 12
Solutions to CBSE Sample Paper - Chemistry Class 12

A first-order reaction takes 69.3 min for 50% completion. What is the time needed for 80% of the reaction to get completed?

(Given: log 5 =0.6990, log 8 = 0.9030, log 2 = 0.3010)

 

Answer:

Half life t1/2 = 0.693 /k

k= 0.693/69.3 = 1/100 = 0.01 min -1

For first order reaction

π‘˜ = 2.303/𝑑 π‘™π‘œπ‘” [π‘…π‘œ]/[𝑅]

𝑑 = 2.303/0.01 π‘™π‘œπ‘” 100/20

𝑑 = 230.3 log 5 (log 5 =0.6990)

t= 160.9 min

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.