Question

The decomposition of iodoethane in the gas phase proceeds according to the following equation. C₂H₅I(g) → C₂H₄(g) + HI(g) At 660. K, k = 7.2 x 10⁻⁴ s-1; at 720. K, k = 1.7 x 10⁻² s-1. What is the rate constant for this first-order decomposition at 325°C? If the initial pressure of iodoethane is 894 torr at 245°C, what is the pressure of iodoethane after three half-lives?

Answer 1

The rate constant for iodoethane decomposition at 325°C is not provided, but after three half-lives, the pressure of iodoethane at 245°C will decrease to approximately 111.75 torr from an initial pressure of 894 torr.

Step-by-step explanation:

The rate constant for the first-order decomposition of iodoethane at a temperature of 325°C cannot be directly calculated without further information, typically requiring an equation such as the Arrhenius equation that relates the rate constants and temperatures. However, answering the second part of the question about the pressure change after three half-lives, we use the concept that for a first-order reaction, the concentration (or in this case, pressure) of the reactant decreases by half during each half-life. Starting with an initial pressure of 894 torr at 245°C, after one half-life, the pressure would be 447 torr, after two half-lives, it would be 223.5 torr, and after three half-lives, it would be approximately 111.75 torr.