Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 14: Problem 169

Consider \(0.10 M\) solutions of the following compounds: \(\mathrm{AlCl}_{3}\) \(\mathrm{NaCN}, \mathrm{KOH}, \mathrm{CsClO}_{4}\), and NaF. Place these solutions in order of increasing \(\mathrm{pH}\).

Short Answer

Expert verified
The order of the 0.10 M solutions based on increasing pH values is as follows: AlCl3 (pH = 0.52, acidic), CsClO4 (pH = 7, neutral), NaCN (pH = 13, basic), KOH (pH = 13, basic), and NaF (pH = 13, basic).

Step by step solution

01

Identify Acidic, Basic, or Neutral Compounds

First, we need to identify if the compounds are acidic, basic, or neutral when dissolved in water. We can do this by examining their dissociation characteristics. 1. AlCl3: This compound will dissociate into Al3+ and Cl- ions. Al3+ ions react with water to produce H+ ions, acting as an acidic substance. 2. NaCN: This compound will dissociate into Na+ and CN- ions. CN- ions react with water to produce OH- ions, acting as a basic substance. 3. KOH: This compound will dissociate into K+ and OH- ions. Since OH- ions are present, it acts as a basic substance. 4. CsClO4: This compound will dissociate into Cs+ and ClO4- ions. Both ions do not react with water, so it will not affect the pH and can be considered neutral. 5. NaF: This compound will dissociate into Na+ and F- ions. F- ions react with water to produce OH- ions, acting as a basic substance.
02

Calculate H+ or OH- Concentrations

Now, we need to calculate the concentration of H+ ions or OH- ions for the acidic and basic compounds in the given 0.10 M solutions. 1. AlCl3: Produced H+ ions; Since it's a 0.10 M solution, and each Al3+ produces 3 H+ ions, [H+] = 0.10 * 3 = 0.30 M 2. NaCN: Produced OH- ions; Since it's a 0.10 M solution, [OH-] = 0.10 M 3. KOH: Produced OH- ions; Since it's a 0.10 M solution, [OH-] = 0.10 M 4. CsClO4: Neutral; no need to calculate the concentrations. 5. NaF: Produced OH- ions; Since it's a 0.10 M solution, [OH-] = 0.10 M
03

Calculate the pH and pOH Values

Now that we have the concentrations of H+ or OH- for each acidic or basic compound, we can use the formulas to calculate the pH and pOH values: - For acidic compound: pH = -log[H+] - For basic compounds: pOH = -log[OH-], and since pH + pOH = 14, we can find the pH as: pH = 14 - pOH 1. AlCl3: pH = -log(0.30) = 0.52 2. NaCN: pOH = -log(0.10) = 1; pH = 14 - 1 = 13 3. KOH: pOH = -log(0.10) = 1; pH = 14 - 1 = 13 4. CsClO4: Neutral; pH = 7 5. NaF: pOH = -log(0.10) = 1; pH = 14 - 1 = 13
04

Sort the Compounds By Increasing pH

Now that we have the pH values for each compound, we can sort them in order of increasing pH: 1. AlCl3: pH = 0.52 (Acidic) 2. CsClO4: pH = 7 (Neutral) 3. NaCN: pH = 13 (Basic) 4. KOH: pH = 13 (Basic) 5. NaF: pH = 13 (Basic) The final order of the solutions based on increasing pH values is: AlCl3, CsClO4, NaCN, KOH, and NaF.

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.

Acidic and Basic Compounds
Understanding the nature of substances as either acidic or basic is crucial in chemistry. Acids are substances that increase the concentration of hydrogen ions (H^+) when dissolved in water, leading to a lower pH value. On the other hand, bases are substances that increase the concentration of hydroxide ions (OH^-), resulting in a higher pH value.

Neutral substances don't significantly alter the concentration of these ions and typically result in a pH of around 7. The behavior of compounds in water, such as AlCl3 being acidic and NaCN, KOH, and NaF being basic, directly influences their resulting pH when in solution.
Dissociation in Water
Dissociation in water is the process where ionic compounds separate into individual ions. This process is key to understanding the reactions of acids and bases. Acids dissociate to produce H^+ ions, while bases dissociate to produce OH^- ions.

For example, when AlCl3 dissociates in water, it releases Al3+ ions which react further with water to produce H^+. In contrast, compounds like NaCN, KOH, and NaF release ions that react with water to yield OH^- ions. CsClO4 is an example of a compound that dissociates without altering the textH^+ or OH^- ion concentration, maintaining a neutral pH.
pH Calculation
To determine the pH of a solution—one of the most common tasks in chemistry—we apply the formula pH = -log[H^+]. The pH scale ranges from 0 to 14, with 0 being very acidic, 7 neutral, and 14 very basic. When dealing with basic solutions, we first find the pOH by using the formula pOH = -log[OH^-], and then calculate the pH with the relationship pH = 14 - pOH.

Understanding this calculation allows us to navigate and predict the acidity or basicity of a solution, as we see with the given compounds where AlCl3 has a lower pH due to its acidity, and NaCN, KOH, and NaF have higher pH values linked to their basicity.
Concentration of Ions
The concentration of ions in a solution is a fundamental concept that heavily influences the pH of the solution. For acidic solutions, we focus on the concentration of H^+ ions, while for basic solutions, we consider the concentration of OH^- ions.

For instance, although each solution of AlCl3, NaCN, KOH, and NaF starts with the same molarity (0.10 M), the resulting concentration of reactive ions varies. AlCl3 releases three times the amount of H^+ ions per formula unit in the dissociation process, leading to a higher concentration of H^+ and a correspondingly lower pH, while NaCN, KOH, and NaF generate a consistent concentration of OH^- and thus share the same higher pH.

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

Will the following oxides give acidic, basic, or neutral solutions when dissolved in water? Write reactions to justify your answers. a. \(\mathrm{CaO}\) b. \(\mathrm{SO}_{2}\) c. \(\mathrm{Cl}_{2} \mathrm{O}\)

Calculate the \(\mathrm{pH}\) of a \(1.0 \times 10^{-7}-M\) solution of \(\mathrm{NaOH}\) in water.

Which of the following represent conjugate acid-base pairs? For those pairs that are not conjugates, write the correct conjugate acid or base for each species in the pair. a. \(\mathrm{H}_{2} \mathrm{O}, \mathrm{OH}^{-}\) c. \(\mathrm{H}_{3} \mathrm{PO}_{4}, \mathrm{H}_{2} \mathrm{PO}_{4}^{-}\) b. \(\mathrm{H}_{2} \mathrm{SO}_{4}, \mathrm{SO}_{4}^{2-}\) d. \(\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}, \mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}^{-}\)

Calculate \(\left[\mathrm{OH}^{-}\right],\left[\mathrm{H}^{+}\right]\), and the \(\mathrm{pH}\) of \(0.20 \mathrm{M}\) solutions of each of the following amines. a. triethylamine \(\left[\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{3} \mathrm{~N}, K_{\mathrm{b}}=4.0 \times 10^{-4}\right]\) b. hydroxylamine \(\left(\mathrm{HONH}_{2}, K_{\mathrm{b}}=1.1 \times 10^{-8}\right)\)

One mole of a weak acid HA was dissolved in \(2.0 \mathrm{~L}\) of solution. After the system had come to equilibrium, the concentration of HA was found to be \(0.45 M\). Calculate \(K_{\mathrm{a}}\) for HA.
See all solutions

Recommended explanations on Chemistry Textbooks

Inorganic Chemistry

Read Explanation

Organic Chemistry

Read Explanation

Making Measurements

Read Explanation

Chemistry Branches

Read Explanation

The Earths Atmosphere

Read Explanation

Physical Chemistry

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