Textbook Question
Most fish need at least 4 ppm dissolved O2 in water for survival. (a) What is this concentration in mol/L?
908
views
Ch.13 - Properties of Solutions
Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970
Not the one you use?Change textbookSelect a different textbook
Table of contents
- Ch.1 - Introduction: Matter, Energy, and Measurement111
- Ch.2 - Atoms, Molecules, and Ions166
- Ch.3 - Chemical Reactions and Reaction Stoichiometry138
- Ch.4 - Reactions in Aqueous Solution127
- Ch.5 - Thermochemistry104
- Ch.6 - Electronic Structure of Atoms109
- Ch.7 - Periodic Properties of the Elements107
- Ch.8 - Basic Concepts of Chemical Bonding102
- Ch.9 - Molecular Geometry and Bonding Theories120
- Ch.10 - Gases122
- Ch.11 - Liquids and Intermolecular Forces79
- Ch.12 - Solids and Modern Materials102
- Ch.13 - Properties of Solutions99
- Ch.14 - Chemical Kinetics153
- Ch.15 - Chemical Equilibrium83
- Ch.16 - Acid-Base Equilibria109
- Ch.17 - Additional Aspects of Aqueous Equilibria117
- Ch.18 - Chemistry of the Environment60
- Ch.19 - Chemical Thermodynamics109
- Ch.20 - Electrochemistry113
- Ch.21 - Nuclear Chemistry79
- Ch.22 - Chemistry of the Nonmetals52
- Ch.23 - Transition Metals and Coordination Chemistry57
- Ch.24 - The Chemistry of Life: Organic and Biological Chemistry7
Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970Not the one you use?Change textbook
Chapter 13, Problem 93a
The “free-base” form of cocaine (C17H21NO4) and its protonated hydrochloride form (C17H22ClO4) are shown below; the free-base form can be converted to the hydrochloride form with one equivalent of HCl. For clarity, not all the carbon and hydrogen atoms are shown; each vertex represents a carbon atom with the appropriate number of hydrogen atoms so that each carbon makes four bonds to other atoms.
a. Which form of cocaine, the free base or the hydrochloride, is relatively water-soluble?
Verified step by step guidance1
Identify the structural differences between the free-base form of cocaine (C17H21NO4) and its hydrochloride form (C17H22ClO4). The hydrochloride form includes an additional HCl group compared to the free-base form.
Understand the impact of the HCl group on solubility. The addition of HCl to the cocaine molecule results in the formation of a salt, which typically enhances solubility in water due to the ionic character of the salt.
Recognize that the free-base form of cocaine is more nonpolar compared to its hydrochloride form. Nonpolar substances tend to be less soluble in water, which is a polar solvent.
Consider the role of hydrogen bonding and ion-dipole interactions. The hydrochloride form can participate in more extensive hydrogen bonding and ion-dipole interactions with water molecules due to its ionic nature, further increasing its solubility.
Conclude that the hydrochloride form of cocaine is relatively more water-soluble than the free-base form due to its ionic character and ability to form favorable interactions with water.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
3mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Solubility and Polarity
Solubility refers to the ability of a substance to dissolve in a solvent, which is often influenced by the polarity of the molecules involved. Polar substances tend to dissolve well in polar solvents (like water), while nonpolar substances are more soluble in nonpolar solvents. The presence of functional groups, such as amines or carboxylic acids, can enhance a compound's polarity and, consequently, its solubility in water.
Recommended video:
Guided course
02:38
Molecular Polarity
Acid-Base Chemistry
Acid-base chemistry involves the transfer of protons (H+) between substances. In this context, the free-base form of cocaine is a neutral base, while the hydrochloride form is a salt formed by the protonation of the base with hydrochloric acid. This protonation increases the compound's polarity, which typically enhances its solubility in water due to the ionic nature of the hydrochloride form.
Recommended video:
Guided course
02:00Arrhenius Acids and Bases
Ionic vs. Molecular Compounds
Ionic compounds, such as hydrochloride salts, are formed from the electrostatic attraction between positively and negatively charged ions. These compounds generally have higher solubility in water compared to molecular compounds, which are held together by covalent bonds. The ionic nature of the hydrochloride form of cocaine allows it to interact more favorably with water molecules, leading to increased solubility compared to its free-base counterpart.
Recommended video:
Guided course
02:11Ionic Compounds Naming
Related Practice
Textbook Question
The osmotic pressure of a 0.010 M aqueous solution of CaCl2 is found to be 0.674 atm at 25 °C. Calculate the van't Hoff factor, i, for the solution.
2345
views
1
rank
Textbook Question
The 'free-base' form of cocaine (C17H21NO4) and its protonated hydrochloride form (C17H21NO4) are shown below; the free-base form can be converted to the hydrochloride form with one equivalent of HCl. For clarity, not all the carbon and hydrogen atoms are shown; each vertex represents a carbon atom with the appropriate number of hydrogen atoms so that each carbon makes four bonds to other atoms (e) How many mL of a concentrated 18.0 M HCl aqueous solution would it take to convert 1.00 kilograms (a 'kilo') of the free-base form of cocaine into its hydrochloride form?
1668
views
Textbook Question
Most fish need at least 4 ppm dissolved O2 in water for survival. (b) What partial pressure of O2 above water is needed to obtain 4 ppm O2 in water at 10 °C? (The Henry's law constant for O2 at this temperature is 1.71⨉10-3 mol/L-atm.)
597
views
Textbook Question
Aerosols are important components of the atmosphere. Does the presence of aerosols in the atmosphere increase or decrease the amount of sunlight that arrives at the Earth's surface, compared to an 'aerosol-free' atmosphere? Explain your reasoning.
507
views