/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 86 An equilibrium mixture of dinitr... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

An equilibrium mixture of dinitrogen tetroxide, \(\mathrm{N}_{2} \mathrm{O}_{4}\), and nitrogen dioxide, \(\mathrm{NO}_{2}\), is \(65.8 \% \mathrm{NO}_{2}\) by mass at 1.00 atm pressure and \(25^{\circ} \mathrm{C}\). Calculate \(K_{c}\) at \(25^{\circ} \mathrm{C}\) for the reaction $$ \mathrm{N}_{2} \mathrm{O}_{4}(g) \rightleftharpoons 2 \mathrm{NO}_{2}(g) $$

Short Answer

Expert verified
The equilibrium constant \(K_c\) is approximately 0.125.

Step by step solution

01

Define Kc expression

The equilibrium constant expression for the formation of nitrogen dioxide is given by \( K_c = \frac{[\text{NO}_2]^2}{[\text{N}_2\text{O}_4]} \). We need to calculate the concentrations of \(\text{NO}_2\) and \(\text{N}_2\text{O}_4\) at equilibrium.
02

Calculate masses and moles

Assume a 100 g sample for ease of calculation, which means it contains 65.8 g of \(\text{NO}_2\) and 34.2 g of \(\text{N}_2\text{O}_4\). The molar masses are 46.01 g/mol for \(\text{NO}_2\) and 92.02 g/mol for \(\text{N}_2\text{O}_4\). Calculate moles: \[ n_{\text{NO}_2} = \frac{65.8}{46.01} \approx 1.431 \text{ mol} \] \[ n_{\text{N}_2\text{O}_4} = \frac{34.2}{92.02} \approx 0.372 \text{ mol} \]
03

Calculate concentrations

The total volume of the gases under 1.00 atm and \(25^{\circ} \text{C} (298 \text{ K})\) can be found via the ideal gas law \( PV = nRT \). The volume of 1 mole of gas at these conditions is approximately 24.45 L. Total moles are \(1.431 + 0.372 = 1.803 \text{ mol}\). \[ V = \frac{1.803 \times 0.0821 \times 298}{1} = 44.1 \, \text{L} \] Now, calculate the concentrations: \[ [\text{NO}_2] = \frac{1.431}{44.1} \approx 0.0324 \text{ M} \] \[ [\text{N}_2\text{O}_4] = \frac{0.372}{44.1} \approx 0.0084 \text{ M} \]
04

Calculate Kc

With the concentrations from the previous step, substitute them into the expression for \(K_c\): \[ K_c = \frac{(0.0324)^2}{0.0084} = \frac{0.00105}{0.0084} \approx 0.125 \]
05

Conclusion

The equilibrium constant \(K_c\) for the reaction \(\text{N}_2\text{O}_4 (g) \rightleftharpoons 2\text{NO}_2 (g)\) at \(25^{\circ}C\) is found to be approximately 0.125.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Ideal Gas Law
The ideal gas law is a fundamental principle in chemistry, connecting several important state variables of a gas: pressure (\( P \)), volume (\( V \)), number of moles (\( n \)), and temperature (\( T \)). The equation is expressed as \( PV = nRT \), where \( R \) is the ideal gas constant. This relationship is crucial for calculating properties of gases under specific conditions.

In this exercise, the ideal gas law helps find the volume needed to calculate the concentrations of nitrogen dioxide and dinitrogen tetroxide. This volume calculation uses the total moles of gas present, temperature in Kelvin (\( 298 \text{ K} \)), and pressure (1.00 atm). Knowing these variables, the equation solves for volume, allowing determination of the molarity of each gas.
  • Use Kelvin for temperature in calculations
  • The ideal gas constant \( R \) is 0.0821 atm·L/mol·K
  • Volume obtained allows calculation of molarity
Nitrogen Dioxide
Nitrogen dioxide, denoted as \( \text{NO}_2 \), is a reddish-brown gas known for its significant role in air pollution and photochemical smog. In this equilibrium study, \( \text{NO}_2 \) is one of the key components whose concentration needs to be calculated while assessing the equilibrium constant \( K_c \).

Understanding its properties, like a molar mass of 46.01 g/mol, assists in converting mass to moles, an essential step in equilibrium calculations. The concentration of \( \text{NO}_2 \) in the mixture is crucial because it influences the value of \( K_c \). In our exercise, you calculate its concentration using the relationship derived from the ideal gas law after determining the moles present.
  • Key pollutant, impacts health and the environment
  • Concentration calculation impacts \( K_c \) determination
  • Conversion from mass is essential for equilibrium analysis
Dinitrogen Tetroxide
Dinitrogen tetroxide, or \( \text{N}_2\text{O}_4 \), appears as a colorless gas and is mainly used as a reagent in chemical reactions. In this context, it is in equilibrium with \( \text{NO}_2 \), meaning the amounts of these gases stay constant over time at equilibrium.

It combines with \( \text{NO}_2 \) according to the equation \( \text{N}_2\text{O}_4 \rightleftharpoons 2\text{NO}_2 \). Understanding the molar mass (92.02 g/mol) and how to switch between mass and concentration is key. For equilibrium calculations, knowing \( \text{N}_2\text{O}_4 \)'s concentration helps to determine \( K_c \), as shown in our exercise when molarity of \( \text{N}_2\text{O}_4 \) is calculated using molar information obtained from its equilibrium position.
  • Important component in chemical equilibrium reactions
  • Balancing chemical equations ensures accurate \( K_c \) calculation
  • Conversion between mass and moles critical for analysis
Chemical Equilibrium
Chemical equilibrium occurs when the rate of the forward reaction equals the rate of the reverse reaction, leading to constant concentrations of reactants and products. In the reaction between \( \text{N}_2\text{O}_4 \) and \( \text{NO}_2 \), equilibrium means that although the individual molecules convert between \( \text{N}_2\text{O}_4 \) to \( \text{NO}_2 \), their overall concentration remains stable.

The equilibrium constant \( K_c \) provides a quantitative measure of the concentrations at which equilibrium is established. It’s essential to accurately measure and calculate the participating molecules' concentrations to find \( K_c \). Higher or lower \( K_c \) indicates which side of the equilibrium is favored, offering insights into the reaction's dynamics.
  • Ensures equilibrium concentrations remain intact over time
  • Indicates the reaction direction's favorability
  • Accurate concentration calculations crucial for correct \( K_c \) value

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Phosgene, \(\mathrm{COCl}_{2}\), used in the manufacture of polyurethane plastics, is prepared from \(\mathrm{CO}\) and \(\mathrm{Cl}_{2}\). $$ \mathrm{CO}(g)+\mathrm{Cl}_{2}(g) \rightleftharpoons \mathrm{COCl}_{2}(g) $$ An equilibrium mixture at \(395^{\circ} \mathrm{C}\) contains \(0.012 \mathrm{~mol} \mathrm{CO}\) and \(0.025 \mathrm{~mol} \mathrm{Cl}_{2}\) per liter, as well as \(\mathrm{COCl}_{2}\). If \(K_{c}\) at \(395^{\circ} \mathrm{C}\) is \(1.23 \times 10^{3},\) what is the concentration of \(\mathrm{COCl}_{2} ?\)

The following equilibrium was studied by analyzing the equilibrium mixture for the amount of \(\mathrm{HCl}\) produced. $$ \mathrm{LaCl}_{3}(s)+\mathrm{H}_{2} \mathrm{O}(g) \rightleftharpoons \mathrm{LaOCl}(s)+2 \mathrm{HCl}(g) $$ A vessel whose volume was \(1.25 \mathrm{~L}\) was filled with \(0.0125 \mathrm{~mol}\) of lanthanum(III) chloride, \(\mathrm{LaCl}_{3}\), and \(0.0250 \mathrm{~mol} \mathrm{H}_{2} \mathrm{O}\). After the mixture came to equilibrium in the closed vessel at \(619^{\circ} \mathrm{C}\), the gaseous mixture was removed and dissolved in more water. Sufficient silver ion was added to precipitate the chloride ion completely as silver chloride. If \(3.59 \mathrm{~g} \mathrm{AgCl}\) was obtained, what is the value of \(K_{c}\) at \(619^{\circ} \mathrm{C} ?\)

Suppose sulfur dioxide reacts with oxygen at \(25^{\circ} \mathrm{C}\). $$ 2 \mathrm{SO}_{2}(g)+\mathrm{O}_{2}(g) \rightleftharpoons 2 \mathrm{SO}_{3}(g) $$ The equilibrium constant \(K_{c}\) equals \(8.0 \times 10^{35}\) at this temperature. From the magnitude of \(K_{c}\), do you think this reaction occurs to any great extent when equilibrium is reached at room temperature? If an equilibrium mixture is \(1.0 \mathrm{M}\) \(\mathrm{SO}_{3}\) and has equal concentrations of \(\mathrm{SO}_{2}\) and \(\mathrm{O}_{2}\), what is the concentration of \(\mathrm{SO}_{2}\) in the mixture? Does this result agree with what you expect from the magnitude of \(K_{c} ?\)

You place 0.600 mol of nitrogen, \(\mathrm{N}_{2}\), and 1.800 mol of hydrogen, \(\mathrm{H}_{2}\), into a reaction vessel at \(450^{\circ} \mathrm{C}\) and \(10.0 \mathrm{~atm}\). The reaction is $$ \mathrm{N}_{2}(g)+3 \mathrm{H}_{2}(g) \rightleftharpoons 2 \mathrm{NH}_{3}(g) $$ What is the composition of the equilibrium mixture if you obtain 0.048 mol of ammonia, \(\mathrm{NH}_{3},\) from it?

A 13.0-L reaction vessel at \(499^{\circ} \mathrm{C}\) contained \(0.852 \mathrm{~mol}\) \(\mathrm{H}_{2}, 0.361 \mathrm{~mol} \mathrm{I}_{2}\), and \(3.84 \mathrm{~mol}\) HI. Assuming that the substances are at equilibrium, find the value of \(K_{c}\) at \(499^{\circ} \mathrm{C}\) for the reaction of hydrogen and iodine to give hydrogen iodide. The equation is $$ \mathrm{H}_{2}(g)+\mathrm{I}_{2}(g) \rightleftharpoons 2 \mathrm{HI}(g) $$

See all solutions

Recommended explanations on Chemistry Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.