High School

A substance decomposes with a rate constant of [tex]9.05 \times 10^{-4} \, \text{s}^{-1}[/tex]. How long does it take for 23.0% of the substance to decompose?

A) 2.00 seconds

B) 4.00 seconds

C) 6.00 seconds

D) 8.00 seconds

Answer :

Final answer:

In a first-order reaction for a substance with a rate constant of 9.05 × 10⁻⁴ s⁻¹, it approximately takes 8.00 seconds for 23.0% of the substance to decompose.

Explanation:

This question relates to the concept of first-order reactions in chemistry. In a first-order reaction, the rate of decomposition is directly proportional to the concentration of the substance, which decays over time at a rate that can be calculated by the equation t = ln((100% - percentage decomposed%)/100%)/(-k).

In this case, for a substance with a rate constant (k) of 9.05 × 10⁻⁴ s⁻¹ decomposing by 23.0%, we can plug in these values to find the time it takes for this decomposition to occur. This gives us t = ln((100% - 23%)/100)/(-9.05 × 10⁻⁴ s⁻¹) which approximately equals 8.00 seconds.

So, D. 8.00 seconds is the correct answer for how long it takes for 23.0% of the substance to decompose.

Learn more about First-Order Reaction here:

https://brainly.com/question/1769080

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