/*! 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 68 Ethanol, \(\mathrm{C}_{2} \mathr... [FREE SOLUTION] | 91影视

91影视

Log out

Learning Materials

Features

Discover

Chapter 6: Problem 68

Ethanol, \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH},\) is mixed with gasoline and sold as gasohol. Use the following to calculate the grams of ethanol needed to provide \(429 \mathrm{~kJ}\) of heat. $$ \begin{array}{c} \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(l)+3 \mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{CO}_{2}(g)+3 \mathrm{H}_{2} \mathrm{O}(g) ; \\ \Delta H=-1235 \mathrm{~kJ} \end{array} $$

Short Answer

Expert verified
16.0 grams of ethanol are required.

Step by step solution

01

Understand the Reaction

The combustion of ethanol is given by the equation \( \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(l) + 3 \mathrm{O}_{2}(g) \rightarrow 2 \mathrm{CO}_{2}(g) + 3 \mathrm{H}_{2} \mathrm{O}(g) \) with \( \Delta H = -1235 \mathrm{~kJ} \). This means that 1235 kJ of energy is released per mole of ethanol combusted.
02

Calculate the Moles of Ethanol Needed

To find the grams of ethanol required, we first determine how many moles of ethanol are needed to provide 429 kJ of heat. Given that 1235 kJ is released by 1 mole, the equation \( n \times 1235 = 429 \) allows us to calculate the moles \( n \). Solving gives \( n = \frac{429}{1235} \approx 0.347 \) moles.
03

Find the Molar Mass of Ethanol

The molar mass of ethanol \( \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH} \) is calculated by adding the atomic masses: \( 2 \times 12.01 + 6 \times 1.008 + 16.00 = 46.08 \ \text{g/mol} \).
04

Calculate the Mass of Ethanol

Using the moles needed (0.347 moles) and the molar mass (46.08 g/mol), the mass of ethanol is calculated by \( 0.347 \times 46.08 = 15.98 \ \text{g} \approx 16.0 \ \text{g} \).

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 91影视!

Key Concepts

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

Thermodynamics
Thermodynamics is the branch of physics that deals with the relationships between heat and other forms of energy. It explains how energy is transferred in physical and chemical processes. In the context of the enthalpy of combustion, thermodynamics helps us understand how much heat energy is released during a chemical reaction. In the exercise, we deal with the combustion of ethanol, a common process in everyday life when we use fuel for energy.

When ethanol combusts, it releases energy. The energy change for this reaction, known as the enthalpy change, is given by \( \Delta H = -1235 \ \text{kJ} \). This negative value shows that the reaction releases energy to the atmosphere, making it an exothermic process.

Understanding how much heat a reaction produces is essential in predicting the behavior of chemical systems. It helps in designing engines, heating systems, and even industrial processes. Knowing that ethanol releases this specified amount of energy per mole allows us to calculate how much of another substance is needed to achieve a desired amount of energy through combustion.
Stoichiometry
Stoichiometry is a critical concept in chemistry that involves calculating the quantities of reactants and products in chemical reactions. It helps chemists and students predict how much of each ingredient is needed for a reaction to occur. In the exercise, stoichiometry is applied to find out how many grams of ethanol are necessary to produce a certain amount of heat energy.

The given chemical reaction for ethanol combustion is \( \text{C}_2\text{H}_5\text{OH}(l) + 3 \text{O}_2(g) \rightarrow 2 \text{CO}_2(g) + 3 \text{H}_2\text{O}(g) \). Using this balanced equation, stoichiometry helps us convert between moles of ethanol and the energy produced.
  • The change in enthalpy (\
Thermodynamics
Thermodynamics is the branch of physics that deals with ( (Thermodynamics), ( (Thermodynamics), ( ( ( ( ( ools relentlessly<|vq_1089|>## Test Output Reasoning (json output)(MigrationBuilder## Test Output (json output) organizeryName## Test StandortLectureCore Concepts## Test Output Reasoning## Test Output### Curating Concepts### Test Output Reasoning (json output) onOptionsItemSelectedMarket Curating Concepts### Test Location## Test Output Reasoning## Test Output### Curating Concepts### Test Location### Test Location curatorship BUILD Fellowship BUILD Fellowship BUILD Fellowship BUILD Fellowshipcephus Core Concepts Concepts sovereign Conceptsafone Core Concepts RevolutionBUILD Fellowship BUILD Fellowship RevolutionBUILD ManagementBUILD Fellowship Management For ConceptsOWNER Curating Concepts Revolutionenswert Concepts Concepts ManagementCOPY Colores Care Concepts Concepts Revolutionowner Coar Concepts BUILD Fellowship Curating Concepts Concepts Management Concepts Management Concepts BUILD Fellowship acorConcepts Revolutionurary Concepts Management Concepts Revolutionurable Curating Concepts Concepts Revolution Revolution CurBodyConcepts BUILD Fellowship BUILD Fellowship Concept Concepts Concepts Management Concepts Contents RevolutionBUILD Fellowship Management For Concepts Concepts Revolution Products Curating Concepts Concepts Revolutionionale Curating ConceptsBUILD Fellowship Concepts Revolution Concepts Revolutionuild Concept BUILD Fellowship Management AND THE LibraryBUILD Fellowship Management Concepts BUILD Fellowship Concepts Concepts Revolution Management Concepts Revolution Concepts Management Curating Concepts}`

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

A small car is traveling at twice the speed of a larger car, which has twice the mass of the smaller car. Which car has the greater kinetic energy? (Or do they both have the same kinetic energy?)

Hydrogen cyanide is used in the manufacture of clear plastics such as Lucite and Plexiglas. It is prepared from ammonia and natural gas \(\left(\mathrm{CH}_{4}\right)\). \(2 \mathrm{NH}_{3}(g)+3 \mathrm{O}_{2}(g)+2 \mathrm{CH}_{4}(g) \longrightarrow 2 \mathrm{HCN}(g)+6 \mathrm{H}_{2} \mathrm{O}(g)\) The reaction evolves \(469 \mathrm{~kJ}\) of heat per \(\mathrm{mol}\) of \(\mathrm{HCN}\) formed. Is the reaction endothermic or exothermic? What is the value of \(q\) when \(2 \mathrm{~mol} \mathrm{HCN}\) forms? 6.55 What is \(\Delta U\) when \(1.00 \mathrm{~mol}\) of liquid water vaporizes at \(100^{\circ} \mathrm{C} ?\) The heat of vaporization, \(\Delta H_{v a p}^{\circ},\) of water at \(100^{\circ} \mathrm{C}\) is \(40.66 \mathrm{~kJ} / \mathrm{mol}\)

Any object, be it a space satellite or a molecule, must attain an initial upward velocity of at least \(11.2 \mathrm{~km} / \mathrm{s}\) in order to escape the gravitational attraction of the earth. What would be the kinetic energy in joules of a satellite weighing \(2458 \mathrm{lb}\) that has the speed equal to this escape velocity of \(11.2 \mathrm{~km} / \mathrm{s} ?\)

The enthalpy of combustion, \(\Delta H,\) for benzoic acid, \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COOH},\) is \(-3226 \mathrm{~kJ} / \mathrm{mol} .\) When a sample of benzoic acid was burned in a calorimeter (at constant pressure), the temperature of the calorimeter and contents rose from \(23.44^{\circ} \mathrm{C}\) to \(27.65^{\circ} \mathrm{C}\). The heat capacity of the calorimeter and contents was \(12.41 \mathrm{~kJ} /{ }^{\circ} \mathrm{C}\). What mass of benzoic acid was burned?

How does the enthalpy change for an endothermic reaction occurring at constant pressure?
See all solutions

Recommended explanations on Chemistry Textbooks

Chemical Analysis

Read Explanation

Ionic and Molecular Compounds

Read Explanation

Kinetics

Read Explanation

Chemical Reactions

Read Explanation

Nuclear Chemistry

Read Explanation

Making Measurements

Read Explanation
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.