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If half life period for a first order reaction in A is 2 minutes, how long will it take [A] to reach (i) `25%` of its initial concentration ii) `10%` of its initial concentration? |
Answer» `k=0.693/t_(1//2) = 0.693/(2min) = 0.3465 min^(-1)` Ist case, `a=100%,(a-x)=25%`, `t=2.303/k loga/(a-x) = (2.303)/(0.3465 min^(-1)) xx log 100/25` `=2.303/(0.3465 min^(-1)) log 4 = (2.303 xx 0.602)/(0.3465 min^(-1)) = 4`min IInd case, `a=100%, (a-x)=10%`, `t=2.303/(0.3465 min^(-1)) log 10 = 6.65 min` |
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