The highly toxic pesticide parathion, (C₂H₅O)₂PSOC₆H₄NO₂, decomposes in the soil via a first order rate law. The rate constant for the decomposition of parathion is 0.0495 days^{- 1}. How long will it take for 50% of the parathion to decompose after it is applied to the land?

Question

Quizplus · Accepted Answer

To solve this problem, we can use the first order rate law equation:

ln([A]t/[A]0) = -kt

where: 
[A]t = concentration of parathion at time t 
[A]0 = initial concentration of parathion 
k = rate constant 
t = time

We want to find the time it takes for 50% of the parathion to decompose, which means [A]t/[A]0 = 0.5. Plugging in the values given in the problem:

ln(0.5) = -0.0495 days^-1 * t

Solving for t:

t = ln(0.5) / 0.0495 days^-1 
t ≈ 2 weeks

Therefore, the answer is B) 2 weeks.

The Highly Toxic Pesticide Parathion, (C2H5O)2PSOC6H4NO2, Decomposes in the Soil

The Highly Toxic Pesticide Parathion, (C₂H₅O)₂PSOC₆H₄NO₂, Decomposes in the Soil