Logout Open In App
Open In App
Warning: foreach() argument must be of type array|object, bool given in /var/www/html/web/app/themes/studypress-core-theme/template-parts/header/mobile-offcanvas.php on line 20

Chapter 13: Problem 3

Consider two ionic solids, both composed of singly-charged ions, that have different lattice energies. (a) Will the solids have the same solubility in water? (b) If not, which solid will be more soluble in water, the one with the larger lattice energy or the one with the smaller lattice energy? Assume that solute-solvent interactions are the same for both solids. [Section 13.1]

Short Answer

Expert verified
(a) No, the two ionic solids with different lattice energies will not have the same solubility in water. (b) The ionic solid with the smaller lattice energy will be more soluble in water, as it requires less energy to overcome the weaker electrostatic forces in the crystal lattice, making it easier for the solid to dissociate and dissolve in water.

Step by step solution

01

Understanding Lattice Energy

Lattice energy is the energy required to separate one mole of an ionic solid into its gaseous ions. It is a measure of the strength of the electrostatic forces that hold the ions together in the crystal lattice. Ionic solids with higher lattice energy are held together more tightly, while ionic solids with lower lattice energy are held together less tightly.
02

Solubility and Lattice Energy

When an ionic solid dissolves in water, it dissociates into its constituent ions. This process involves overcoming the lattice energy so that the ions can be surrounded by water molecules. In order to dissolve in water, the energy gained from solute-solvent interactions must be greater than the energy required to overcome the lattice energy.
03

Comparing Solubility of Ionic Solids with Different Lattice Energies

The solubility of an ionic solid in water depends on the balance between the energy required to overcome the lattice energy and the energy gained from solute-solvent interactions. Since the exercise assumes that the solute-solvent interactions are the same for both solids, the solubility of the two solids will be determined by their lattice energies.
04

Answering the Exercise Questions

(a) Will the solids have the same solubility in water? No, the two ionic solids with different lattice energies will not have the same solubility in water. (b) Which solid will be more soluble in water, the one with the larger lattice energy or the one with the smaller lattice energy? The ionic solid with the smaller lattice energy will be more soluble in water. This is because less energy is required to overcome the weaker electrostatic forces in the crystal lattice, making it easier for the solid to dissociate and dissolve in water.

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.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

Key Concepts

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

Solubility
Solubility refers to the ability of a substance to dissolve in a solvent, forming a homogeneous solution. When it comes to ionic solids dissolving in water, the process involves breaking apart the lattice structure of the solid into its individual ions. These ions then interact with water molecules, which effectively surround and disperse the ions throughout the solution. This process depends on various factors, including temperature and the inherent properties of the solute and solvent.

In the context of ionic solids, solubility is largely determined by the interplay between two energies: the lattice energy and the hydration energy. Lattice energy is the energy needed to break up the ionic lattice into individual ions, while hydration energy is released when these ions are surrounded by water molecules. For a solute to dissolve, the energy gained from hydration must surpass the lattice energy. Consequently, ionic solids with lower lattice energies are generally more soluble than those with higher lattice energies, assuming other conditions like temperature and solute-solvent interactions remain constant.

Understanding this balance is crucial to predicting and explaining why different ionic compounds have varying solubilities in water.
Ionic Solids
Ionic solids are compounds composed of positively charged ions, or cations, and negatively charged ions, or anions. These ions are held together in a lattice structure by strong electrostatic forces known as ionic bonds.

Due to their structure, ionic solids have several common properties:
  • High melting and boiling points: The strong electrostatic forces require a significant amount of energy to overcome.
  • Brittleness: While they are hard, applying force can shift the ions and cause repulsion, leading to the structure shattering.
  • Conductivity when molten or dissolved in water: The ions are free to move and carry charge when not held in a solid lattice.
Though robust, the lattice structure of ionic solids can be disrupted when the solid is dissolved in a solvent like water. Once dissolved, the ionic solid separates into its individual ions, which are then free to move around. This freedom of movement is directly related to the solubility of ionic compounds in water. Lower lattice energy makes it easier for the structure to dissociate, thereby increasing solubility.
Electrostatic Forces
Electrostatic forces are at the heart of the stability and behavior of ionic solids. These forces are the attractive interactions between oppositely charged ions within the crystal lattice. The strength of these forces is directly related to the lattice energy, which can be thought of as a measure of how tightly ions are held together in the solid state.

In the context of lattice energy, the magnitude of electrostatic forces is determined by several factors:
  • Charge of the ions: Greater charges lead to stronger forces and higher lattice energies.
  • Sizes of the ions: Smaller ions mean shorter distances between them, leading to stronger interactions.
  • Crystal packing: The way ions arrange themselves in the lattice can also influence the strength of these forces.
When considering the dissolution of ionic solids in water, overcoming these electrostatic forces is necessary. This is why lattice energy is such a crucial factor in determining solubility. Lower lattice energies mean weaker forces to overcome, allowing the ions to more easily disperse and interact with water molecules. Understanding these electrostatic interactions is essential for predicting the behavior of ionic compounds in various chemical contexts.

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

By referring to Figure 13.15, determine whether the addition of \(40.0 \mathrm{~g}\) of each of the following ionic solids to \(100 \mathrm{~g}\) of water at \(40^{\circ} \mathrm{C}\) will lead to a saturated solution: (a) \(\mathrm{NaNO}_{3}\), (b) \(\mathrm{KCl}_{\text {, }}\) (c) \(\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\), (d) \(\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}\)

An ionic compound has a very negative \(\Delta H_{\text {soln }}\) in water. (a) Would you expect it to be very soluble or nearly insoluble in water? (b) Which term would you expect to be the largest negative number: \(\Delta H_{\text {solvent }} \Delta H_{\text {solute }}\) or \(\Delta H_{\text {mix }}\) ?

A "canned heat" product used to warm buffet dishes consists of a homogeneous mixture of ethanol \(\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)\) and paraffin, which has an average formula of \(\mathrm{C}_{24} \mathrm{H}_{50}\). What mass of \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\) should be added to \(620 \mathrm{~kg}\) of the paraffin to produce 8 torr of ethanol vapor pressure at \(35^{\circ} \mathrm{C}\) ? The vapor pressure of pure ethanol at \(35^{\circ} \mathrm{C}\) is 100 torr.

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?

(a) A sample of hydrogen gas is generated in a closed container by reacting \(2.050 \mathrm{~g}\) of zinc metal with \(15.0 \mathrm{~mL}\) of \(1.00 \mathrm{M}\) sulfuric acid. Write the balanced equation for the reaction, and calculate the number of moles of hydrogen formed, assuming that the reaction is complete. (b) The volume over the solution in the container is \(122 \mathrm{~mL}\). Calculate the partial pressure of the hydrogen gas in this volume at \(25^{\circ} \mathrm{C}\), ignoring any solubility of the gas in the solution. (c) The Henry's law constant for hydrogen in water at \(25^{\circ} \mathrm{C}\) is \(7.8 \times 10^{-4} \mathrm{~mol} / \mathrm{L}\)-atm. Estimate the number of moles of hydrogen gas that remain dissolved in the solution. What fraction of the gas molecules in the system is dissolved in the solution? Was it reasonable to ignore any dissolved hydrogen in part (b)? [13.111] The following table presents the solubilities of several gases in water at \(25^{\circ} \mathrm{C}\) under a total pressure of gas and water vapor of \(1 \mathrm{~atm}\). (a) What volume of \(\mathrm{CH}_{4}(\mathrm{~g})\) under standard conditions of temperature and pressure is contained in \(4.0 \mathrm{~L}\) of a saturated solution at \(25^{\circ} \mathrm{C}\) ? (b) Explain the variation in solubility among the hydrocarbons listed (the first three compounds), based on their molecular structures and intermolecular forces. (c) Compare the solubilities of \(\mathrm{O}_{2}, \mathrm{~N}_{2}\), and \(\mathrm{NO}\), and account for the variations based on molecular structures and intermolecular forces. (d) Account for the much larger values observed for \(\mathrm{H}_{2} \mathrm{~S}\) and \(\mathrm{SO}_{2}\) as compared with the other gases listed. (e) Find several pairs of substances with the same or nearly the same molecular masses (for example, \(\mathrm{C}_{2} \mathrm{H}_{4}\) and \(\mathrm{N}_{2}\) ), and use intermolecular interactions to explain the differences in their solubilities.
See all solutions

Recommended explanations on Chemistry Textbooks

Chemical Analysis

Read Explanation

Ionic and Molecular Compounds

Read Explanation

Nuclear Chemistry

Read Explanation

Chemistry Branches

Read Explanation

The Earths Atmosphere

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.

Sign-up for free