A gas-phase decomposition is first-order with respect to the reactant, R. If the initial concentration of R is 1.0 × 10^-4 mol L^-1 and the rate constant k = 1.08 × 10^-6 s^-1, what concentration of R remains after 25 days?

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Quizplus · Accepted Answer

The integrated rate law for a first-order reaction is:ln[R]t = -kt + ln[R]0where [R]t is the concentration of R at time t, k is the rate constant, and [R]0 is the initial concentration of R.We can use this equation to calculate the concentration of R remaining after 25 days:ln[R]t = -(1.08 × 10^-6 s^-1)(25 days)(86400 s/day) + ln(1.0 × 10^-4 mol L^-1)ln[R]t = -2.30[R]t = 9.7 × 10^-6 mol L^-1

A Gas-Phase Decomposition Is First-Order with Respect to the Reactant