# Q. 75% of a first order reaction was completed in 32 minutes. When was 50% of the reaction completed

COMEDK COMEDK 2010Chemical Kinetics

Solution:

## $k=\frac{2.303}{t}log_{10} \left(\frac{a}{a-x}\right)$$k=\frac{2.303}{t}log \left(\frac{100}{100-75}\right)....(i)$$k= \frac{2.303}{t}log \left(\frac{100}{100-50}\right).....(ii)$From the two eqns. (i) and (ii), t = 16 minutes.

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