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NEET CHEMISTRYMedium

What is the rate constant for a reaction if the time taken by the first-order decomposition of SO2Cl2\text{SO}_2\text{Cl}_2 to decompose to 40%40\% is 560 seconds560 \text{ seconds}? [Given: log2.5=0.3979\log 2.5 = 0.3979]

A

2.726×105 min12.726 \times 10^{-5} \text{ min}^{-1}

B

2.276×105 min12.276 \times 10^{-5} \text{ min}^{-1}

C

2.216×105 min12.216 \times 10^{-5} \text{ min}^{-1}

D

None of the above

Step-by-Step Solution

For a first-order reaction, the integrated rate equation is given by: k=2.303tlog[R]0[R]k = \frac{2.303}{t} \log \frac{[R]_0}{[R]} Given: The substance decomposes to 40%40\%, meaning the remaining concentration is [R]=40%[R] = 40\% of the initial concentration [R]0[R]_0. So, [R]0[R]=10040=2.5\frac{[R]_0}{[R]} = \frac{100}{40} = 2.5 Time, t=560 st = 560 \text{ s} Substituting the values into the rate equation: k=2.303560log(2.5)k = \frac{2.303}{560} \log(2.5) Given log2.5=0.3979\log 2.5 = 0.3979, k=2.303×0.3979560 s1=0.91636560 s1=1.636×103 s1k = \frac{2.303 \times 0.3979}{560} \text{ s}^{-1} = \frac{0.91636}{560} \text{ s}^{-1} = 1.636 \times 10^{-3} \text{ s}^{-1} To find the rate constant in min1\text{min}^{-1}, we multiply by 60 s/min60 \text{ s/min}: k=1.636×103 s1×60 s/min=0.09816 min1=9.816×102 min1k = 1.636 \times 10^{-3} \text{ s}^{-1} \times 60 \text{ s/min} = 0.09816 \text{ min}^{-1} = 9.816 \times 10^{-2} \text{ min}^{-1} Since none of the options match the correct calculated value, 'None of the above' is the correct choice.

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