# At a particular temperature the first-order gas-phase reaction 2N_2O_5 rightarrow 2N_2O_4 + O_2...

## Question:

At a particular temperature the first-order gas-phase reaction 2N_2O_5 rightarrow 2N_2O_4 + O_2 has a half-life for the disappearance of dinitrogen pentoxide of 3240 s.

If 1.00 atm of N_2O_5 is introduced into an evacuated 5.00 L flask, what will be the total pressure of the gases in the flask after 1.50 hours?

• A) 0.685 atm
• B) 1.00 atm
• C) 0.315 atm
• D) 1.68 atm
• E) 1.34 atm

## First-Order Kinetics:

The integrated rate law of a first-order reaction is given below:

{eq}\displaystyle \ln A = \ln A_0 - kt \\ {/eq}

The rate constant is related to the half-life of a first-order reaction:

{eq}\displaystyle t = \frac{\ln 2}{k} \\ {/eq}

The total pressure can be expressed in terms of the extent and initial concentrations.

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The rate constant of the reaction is:

{eq}\displaystyle k = \frac{\ln 2}{3240 \ s \times \frac{1 \ h}{3600 \ s}} = 0.77 \ h^{-1} \\ {/eq}

Let x be...

First-Order Reactions: Definition & Mathematical Representation

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Chapter 19 / Lesson 6
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In this lesson, we'll talk about first-order reactions like radioactive decay. We'll use the mathematical descriptions of these reactions to discuss their behavior.