Domanda del libro di testo
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.
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Ch.13 - Properties of Solutions
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232
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TOC.tableOfContents
- Ch.1 - Introduction: Matter, Energy, and Measurement177
- Ch.2 - Atoms, Molecules, and Ions231
- Ch.3 - Chemical Reactions and Reaction Stoichiometry216
- Ch.4 - Reactions in Aqueous Solution189
- Ch.5 - Thermochemistry175
- Ch.6 - Electronic Structure of Atoms168
- Ch.7 - Periodic Properties of the Elements150
- Ch.8 - Basic Concepts of Chemical Bonding177
- Ch.9 - Molecular Geometry and Bonding Theories200
- Ch.10 - Gases179
- Ch.11 - Liquids and Intermolecular Forces113
- Ch.12 - Solids and Modern Materials154
- Ch.13 - Properties of Solutions157
- Ch.14 - Chemical Kinetics199
- Ch.15 - Chemical Equilibrium128
- Ch.16 - Acid-Base Equilibria164
- Ch.17 - Additional Aspects of Aqueous Equilibria163
- Ch.18 - Chemistry of the Environment105
- Ch.19 - Chemical Thermodynamics164
- Ch.20 - Electrochemistry171
- Ch.21 - Nuclear Chemistry122
- Ch.22 - Chemistry of the Nonmetals82
- Ch.23 - Transition Metals and Coordination Chemistry79
- Ch.24 - The Chemistry of Life: Organic and Biological Chemistry16
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232Non è quello che usi tu?Cambia libro di testo
Capitolo 13, Problema 87
An “emulsifying agent” is a compound that helps stabilize a hydrophobic colloid in a hydrophilic solvent (or a hydrophilic colloid in a hydrophobic solvent). Which of the following choices is the best emulsifying agent? (a) CH3COOH, (b) CH3CH2CH2COOH, (c) CH3(CH2)11COOH, (d) CH3(CH2)11COONa.
Guida verificata passo dopo passo1
Step 1: Understand the role of an emulsifying agent. An emulsifying agent stabilizes a colloid by reducing the surface tension between two immiscible liquids, such as oil and water. It typically has both hydrophilic (water-attracting) and hydrophobic (water-repelling) parts.
Step 2: Analyze the structure of each compound. Look for the presence of both hydrophilic and hydrophobic groups. Carboxylic acids (COOH) and their salts (COONa) are common emulsifying agents due to their polar and non-polar regions.
Step 3: Evaluate each option. (a) CH3COOH is acetic acid, with a short hydrophobic chain and a hydrophilic carboxyl group. (b) CH3CH2CH2COOH is butyric acid, with a slightly longer hydrophobic chain. (c) CH3(CH2)11COOH is lauric acid, with a much longer hydrophobic chain. (d) CH3(CH2)11COONa is sodium laurate, a salt of lauric acid, with a long hydrophobic chain and a hydrophilic ionic group.
Step 4: Consider the effectiveness of each compound as an emulsifying agent. The presence of a charged group, like the sodium ion in option (d), enhances the hydrophilic nature, making it more effective in stabilizing emulsions.
Step 5: Conclude that the best emulsifying agent is likely the one with a balance of hydrophobic and hydrophilic properties, and the presence of an ionic group can significantly enhance emulsification.
Concetti chiave
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Emulsifying Agents
Emulsifying agents are substances that help stabilize emulsions, which are mixtures of two immiscible liquids, such as oil and water. They work by reducing the surface tension between the liquids, allowing for the formation of small droplets that remain suspended. Common examples include surfactants, which have both hydrophilic (water-attracting) and hydrophobic (water-repelling) properties, enabling them to interact with both phases.
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01:21
Chelating Agents
Hydrophilic and Hydrophobic Properties
Hydrophilic substances are attracted to water and tend to dissolve or mix well in it, while hydrophobic substances repel water and do not mix well. In the context of emulsifying agents, a good emulsifier typically has a hydrophilic head and a hydrophobic tail, allowing it to interact with both the aqueous and oily phases of an emulsion. This dual nature is crucial for stabilizing emulsions and preventing separation.
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02:54Physical Properties
Colloids and Stability
Colloids are mixtures where tiny particles are dispersed throughout a continuous medium, such as oil droplets in water. The stability of colloids can be affected by factors like particle size, concentration, and the presence of emulsifying agents. A stable colloid will not separate over time, and the choice of emulsifying agent can significantly influence the stability by preventing coalescence of the dispersed phase.
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02:38Suspensions and Colloids
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Domanda del libro di testo
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.
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Domanda del libro di testo
A dilute aqueous solution of an organic compound soluble in water is formed by dissolving 2.35 g of the compound in water to form 0.250 L of solution. The resulting solution has an osmotic pressure of 0.605 atm at 25 °C. Assuming that the organic compound is a nonelectrolyte, what is its molar mass?
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Domanda del libro di testo
The 'free-base' form of cocaine (C17H21NO4) and its protonated hydrochloride form (C17H22ClNO4) 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) One of these forms of cocaine is relatively water-soluble: which form, the free base or the hydrochloride?
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