A certain substance X decomposes. Fifty percent of X remains after 100 minutes. How much X remains after 200 minutes if the reaction order with respect to X is (c) second order?
Ch.14 - Chemical Kinetics
Chapter 14, Problem 112
Ethyl chloride vapor decomposes by the first-order reaction: C2H5Cl -> C2H4 + HCl. The activation energy is 249 kJ/mol, and the frequency factor is 1.6 * 10^14 s^-1. Find the temperature at which the rate of the reaction would be twice as fast.
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Identify the Arrhenius equation: $k = A e^{-\frac{E_a}{RT}}$, where $k$ is the rate constant, $A$ is the frequency factor, $E_a$ is the activation energy, $R$ is the gas constant, and $T$ is the temperature in Kelvin.
Recognize that the problem asks for the temperature at which the rate of the reaction is twice as fast, meaning $k_2 = 2k_1$.
Use the Arrhenius equation to set up the relationship between the two rate constants: $\frac{k_2}{k_1} = \frac{A e^{-\frac{E_a}{RT_2}}}{A e^{-\frac{E_a}{RT_1}}} = 2$.
Simplify the equation: $e^{-\frac{E_a}{RT_2}} = 2 e^{-\frac{E_a}{RT_1}}$ and take the natural logarithm of both sides to solve for $T_2$: $-\frac{E_a}{RT_2} = \ln(2) - \frac{E_a}{RT_1}$.
Rearrange the equation to solve for $T_2$: $T_2 = \frac{E_a}{R(\ln(2) + \frac{E_a}{RT_1})}$, where $E_a = 249 \text{ kJ/mol}$, $R = 8.314 \text{ J/mol K}$, and $T_1$ is the initial temperature.
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The half-life for radioactive decay (a first-order process) of plutonium- 239 is 24,000 years. How many years does it take for one mole of this radioactive material to decay until just one atom remains?
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Open Question
The energy of activation for the decomposition of 2 mol of HI to H2 and I2 in the gas phase is 185 kJ. The heat of formation of HI(g) from H2(g) and I2(g) is -5.65 kJ/mol. Find the energy of activation for the reaction of 1 mol of H2 and 1 mol of I2 to form 2 mol of HI in the gas phase.
Textbook Question
Ethyl chloride vapor decomposes by the first-order reaction: C2H5Cl → C2H4 + HCl The activation energy is 249 kJ/mol, and the frequency factor is 1.6⨉1014 s-1. Find the value of the rate constant at 710 K.
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Textbook Question
Ethyl chloride vapor decomposes by the first-order reaction: C2H5Cl → C2H4 + HCl The activation energy is 249 kJ/mol, and the frequency factor is 1.6⨉1014 s-1. What fraction of the ethyl chloride decomposes in 15 minutes at this temperature?
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