/*! 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 18 When ammonium chloride dissolves... [FREE SOLUTION] | 91影视

91影视

Log out

Learning Materials

Features

Discover

Chapter 13: Problem 18

When ammonium chloride dissolves in water, the solution becomes colder. (a) Is the solution process exothermic or endothermic? (b) Why does the solution form?

Short Answer

Expert verified
(a) The solution process is endothermic. (b) The solution forms due to increased entropy.

Step by step solution

01

Understanding Endothermic and Exothermic Processes

To understand if a process is exothermic or endothermic, we observe the heat exchange with the surroundings. An endothermic process absorbs heat from the surroundings, making them cooler, while an exothermic process releases heat to the surroundings, making them warmer.
02

Determining the Nature of Ammonium Chloride Dissolution

Since the solution becomes colder when ammonium chloride dissolves in water, it indicates that the process absorbs heat from the surroundings. This means that the dissolution process is endothermic.
03

Understanding Why the Solution Forms

Despite being endothermic, the dissolution process occurs because of entropy. When ammonium chloride dissolves, the ions become more disordered and dispersed in the water, leading to an increase in entropy, which can drive the dissolution process.

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.

Ammonium Chloride Dissolution
When ammonium chloride is added to water, an interesting phenomenon occurs. The mixture becomes colder, a clear indication of an endothermic process.
An endothermic process involves the absorption of heat by the system from its surroundings. In the case of ammonium chloride, when it dissolves, it requires energy to break the ionic bonds within the solid.
  • Ionic compounds like ammonium chloride are composed of positive and negative ions held together by strong ionic bonds.
  • When these compounds dissolve, energy is necessary to overcome these attractive forces so the ions can disperse through the solution.
The cold sensation upon dissolution confirms that the system is taking in energy from its surroundings to facilitate this breakup, making the process endothermic.
Entropy
Entropy is a fundamental concept that plays a crucial role in the dissolution of ammonium chloride, even though it is an endothermic process.
Entropy is a measure of disorder or randomness in a system. In general, the universe tends to favor states that have a higher degree of disorder.
  • When a solid like ammonium chloride dissolves in water, the ions that were once rigidly arranged in the solid begin to move freely in the liquid state.
  • This increased freedom of movement translates to an increase in the system's disorder, thereby raising its entropy.
Even if energy is absorbed in the form of heat (endothermic process), the increase in entropy can make the dissolution process favorable. As entropy increases, it can outweigh the energetic costs, making processes like dissolution spontaneous.
Solution Formation
The formation of a solution, especially in the case of ammonium chloride and water, is driven by several factors. It is a delicate balance between enthalpy and entropy.
Although this dissolution process is endothermic, the solution still forms due to the significant increase in entropy.
  • The attraction between molecules in the solute and solvent must be strong enough to compensate for the energy needed to break apart the solute molecules.
  • However, as entropy rises due to the dispersal of ions, it can favor solution formation even when energy is absorbed.
The natural tendency for systems to reach a state of maximum entropy is a common driver for solution formation, resulting in processes where substances dissolve despite an initial energy input (like heat absorbed in the case of endothermic reactions). This process ensures that the microscopic particles become evenly distributed in the solvent, creating a uniform solution.

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

You make a solution of a nonvolatile solute with a liquid solvent. Indicate if each of the following statements is true or false. (a) The freezing point of the solution is unchanged by addition of the solvent. (b) The solid that forms as the solution freezes is nearly pure solute. (c) The freezing point of the solution is independent of the concentration of the solute. (d) The boiling point of the solution increases in proportion to the concentration of the solute. \((\mathbf{e})\) At any temperature, the vapor pressure of the solvent over the solution is lower than what it would be for the pure solvent.

Proteins can be precipitated out of aqueous solution by the addition of an electrolyte; this process is called "salting out" the protein. (a) Do you think that all proteins would be precipitated out to the same extent by the same concentration of the same electrolyte? (b) If a protein has been salted out, are the protein-protein interactions stronger or weaker than they were before the electrolyte was added? (c) A friend of yours who is taking a biochemistry class says that salting out works because the waters of hydration that surround the protein prefer to surround the electrolyte as the electrolyte is added; therefore, the protein's hydration shell is stripped away, leading to protein precipitation. Another friend of yours in the same biochemistry class says that salting out works because the incoming ions adsorb tightly to the protein, making ion pairs on the protein surface, which end up giving the protein a zero net charge in water and therefore leading to precipitation. Discuss these two hypotheses. What kind of measurements would you need to make to distinguish between these two hypotheses?

Soaps consist of compounds such as sodium stearate, \(\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{16} \mathrm{COO}^{-} \mathrm{Na}^{+},\) that have both hydrophobic and hydrophilic parts. Consider the hydrocarbon part of sodium stearate to be the "tail" and the charged part to be the "head." (a) Which part of sodium stearate, head or tail, is more likely to be solvated by water? (b) Grease is a complex mixture of (mostly) hydrophobic compounds. Which part of sodium stearate, head or tail, is most likely to bind to grease? (c) If you have large deposits of grease that you want to wash away with water, you can see that adding sodium stearate will help you produce an emulsion. What intermolecular interactions are responsible for this?

At ordinary body temperature \(\left(37^{\circ} \mathrm{C}\right),\) the solubility of \(\mathrm{N}_{2}\) in water at ordinary atmospheric pressure is \(0.015 \mathrm{~g} / \mathrm{L}\). Air is approximately \(78 \mathrm{~mol} \% \mathrm{~N}_{2} .\) (a) Calculate the number of moles of \(\mathrm{N}_{2}\) dissolved per liter of blood, assuming blood is a simple aqueous solution. (b) At a depth of \(30.5 \mathrm{~m}\) in water, the external pressure is \(405 \mathrm{kPa}\). What is the solubility of \(\mathrm{N}_{2}\) from air in blood at this pressure? (c) If a scuba diver suddenly surfaces from this depth, how many milliliters of \(\mathrm{N}_{2}\) gas, in the form of tiny bubbles, are released into the bloodstream from each liter of blood?

Ascorbic acid (vitamin C, \(\mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{6}\) ) is a water-soluble vitamin. A solution containing \(80.5 \mathrm{~g}\) of ascorbic acid dissolved in \(210 \mathrm{~g}\) of water has a density of \(1.22 \mathrm{~g} / \mathrm{mL}\) at \(55^{\circ} \mathrm{C}\). Calculate (a) the mass percentage, \((\mathbf{b})\) the mole fraction, \((\mathbf{c})\) the molality, \((\mathbf{d})\) the molarity of ascorbic acid in this solution.
See all solutions

Recommended explanations on Chemistry Textbooks

Physical Chemistry

Read Explanation

Chemical Reactions

Read Explanation

Ionic and Molecular Compounds

Read Explanation

Inorganic Chemistry

Read Explanation

Organic Chemistry

Read Explanation

Chemical Analysis

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.