At high temperatures, the decomposition of cyclobutane is a first-order reaction. Its activation energy is \(262 \mathrm{~kJ} / \mathrm{mol}\). At \(477^{\circ} \mathrm{C}\), its half-life is \(5.00 \mathrm{~min}\). What is its half-life (in seconds) at \(527^{\circ} \mathrm{C}\) ?

Short Answer

Expert verified
In summary, the half-life of cyclobutane at \(527^\circ \mathrm{C}\) is approximately \(42.67 \mathrm{~seconds}\). This is determined by first finding the rate constant at \(477^\circ \mathrm{C}\), using the Arrhenius equation to find the rate constant at \(527^\circ \mathrm{C}\), and finally calculating the half-life at the new temperature.

Step by step solution

01

Find the initial rate constant (k) at \(477^\circ \mathrm{C}\)

For a first-order reaction, we can use the half-life formula, \(t_{1/2} = \frac{0.693}{k}\). At \(477^\circ \mathrm{C}\), we are given the half-life as \(5.00 \mathrm{~min}\), which is equal to \(300 \mathrm{~s}\). So, we can rewrite the formula as \(300 \mathrm{~s} = \frac{0.693}{k}\), and we can solve for k. $$k = \frac{0.693}{300 \mathrm{~s}}$$ Now, calculate k: $$k \approx 2.31 \times 10^{-3} \mathrm{s}^{-1}$$
02

Use the Arrhenius equation to find k at \(527^\circ \mathrm{C}\)

The Arrhenius equation is given by: $$k_2 = k_1 \cdot e^{\frac{-E_a}{R} \cdot (\frac{1}{T_2} - \frac{1}{T_1})}$$ where \(k_1\) is the initial rate constant at temperature \(T_1\), \(k_2\) is the rate constant at temperature \(T_2\), \(E_a\) is the activation energy, and \(R\) is the gas constant. In this problem, we have: - \(k_1 = 2.31 \times 10^{-3} \mathrm{s}^{-1}\) - \(E_a = 262 \, \mathrm{kJ/mol} = 262 \times 10^3 \, \mathrm{J/mol}\) - \(T_1 = 477^\circ \mathrm{C} = 750.15 \, \mathrm{K}\) - \(T_2 = 527^\circ \mathrm{C} = 800.15 \, \mathrm{K}\) - \(R = 8.314 \, \mathrm{J/(mol \, K)}\) Plug these values into the equation and solve for \(k_2\). $$k_2 = (2.31 \times 10^{-3} \mathrm{s}^{-1}) \cdot e^{\frac{-(262 \times 10^3 \mathrm{J/mol})}{(8.314 \mathrm{J/(mol \, K)})} \cdot (\frac{1}{800.15 \mathrm{K}} - \frac{1}{750.15 \mathrm{K}})}$$ After calculation, we obtain: $$k_2 \approx 1.624 \times 10^{-2} \mathrm{s}^{-1}$$
03

Calculate the half-life at \(527^\circ \mathrm{C}\)

Now that we have found the rate constant at \(527^\circ \mathrm{C}\), we can calculate the half-life using the formula \(t_{1/2} = \frac{0.693}{k}\). $$t_{1/2} = \frac{0.693}{1.624 \times 10^{-2} \mathrm{s}^{-1}}$$ After calculation, we obtain: $$t_{1/2} \approx 42.67 \mathrm{s}$$ So the half-life of cyclobutane at \(527^\circ \mathrm{C}\) is approximately \(42.67 \mathrm{~seconds}\).

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Most popular questions from this chapter

The first-order rate constant for the decomposition of a certain hormone in water at \(25^{\circ} \mathrm{C}\) is \(3.42 \times 10^{-4}\) day \(^{-1}\). (a) If a \(0.0200 \mathrm{M}\) solution of the hormone is stored at \(25^{\circ} \mathrm{C}\) for two months, what will its concentration be at the end of that period? (b) How long will it take for the concentration of the solution to drop from \(0.0200 M\) to \(0.00350 \mathrm{M} ?\) (c) What is the half-life of the hormone?

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