13: Solutions and their Physical Properties
- Page ID
- 480987
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- 13.1: Types of Solutions - Some Terminology
- In all solutions, whether gaseous, liquid, or solid, the substance present in the greatest amount is the solvent, and the substance or substances present in lesser amounts are the solute(s). The solute does not have to be in the same physical state as the solvent, but the physical state of the solvent usually determines the state of the solution. As long as the solute and solvent combine to give a homogeneous solution, the solute is said to be soluble in the solvent.
- 13.2: Solution Concentration
- Molarity (M) (mol solute/L solution) is widely used but temp-dependent. Molality (m) (mol solute/kg solvent) is temp-independent and essential for colligative properties. Mass % (solute mass/solution mass × 100%) is intuitive for mixtures. Mole fraction (X) (solute moles/total moles) suits gas mixtures. ppm/ppb quantify trace solutes. Units interconvert using density and molar masses.
- 13.3: Intermolecular Forces and the Solution Process
- Molecular structure plays an important role in determining solubility. By examining the enthalpy (ΔH) of solution, we can make predictions of solubility that reflect the intermolecular forces involved when substances are mixed.
- 13.4: Solution Formation and Equilibrium
- Solution formation is an equilibrium process that depends on temperature, pressure, and solubility. This sections describes solution formation at the molecular level through the lens of equilibrium.
- 13.5: Solubilities of Gases
- Gas solubility is governed by Henry's Law, so dissolved concentration (C) is proportional to its partial pressure (P), expressed as C =kHP. Solubility decreases with rising temperature for most gases (e.g., O₂, CO₂) due to exothermic dissolution, but increases slightly for light gases (H₂, He). Polar gases (NH₃, SO₂) exhibit higher solubility in water than nonpolar gases (N₂, CH₄) due to IMF's. Key applications include carbonated beverages and decompression sickness.
- 13.6: Vapor Pressures of Solutions
- Nonvolatile solutes reduce a solvent's vapor pressure because solute particles occupy surface space, hindering solvent evaporation. Raoult's Law quantifies this. The vapor pressure lowering is proportional to the solute's mole fraction. For volatile solutes, the total vapor pressure is the sum of each component's partial vapor pressure. Ideal solutions obey Raoult's Law. But, real solutions often show deviations due to differences in solute-solvent vs. pure component intermolecular forces.
- 13.7: Osmotic Pressure
- Osmotic pressure is a colligative property of solutions that is observed using a semipermeable membrane, a barrier with pores small enough to allow solvent molecules to pass through but not solute molecules or ions. The net flow of solvent through a semipermeable membrane is called osmosis (from the Greek osmós, meaning “push”). The direction of net solvent flow is always from the side with the lower concentration of solute to the side with the higher concentration.
- 13.8: Freezing-Point Depression and Boiling-Point Elevation of Nonelectrolyte Solutions
- Many of the physical properties of solutions differ significantly from those of the pure substances discussed in earlier chapters, and these differences have important consequences. For example, the limited temperature range of liquid water (0°C–100°C) severely limits its use. Aqueous solutions have both a lower freezing point and a higher boiling point than pure water.
- 13.9: Solutions of Electrolytes
- If a solution contains electrolytes, then a new factor must be considered when calculating the osmotic pressure of the solution. Here we introduce this new factor, called the van't Hoff Factor.
- 13.10: Colloidal Mixtures
- This section exactly defines a colloid and how it is different from a suspension. Suspensions are heterogeneous mixtures where large particles settle out, while colloids are mixtures with smaller particles that remain dispersed and can be classified as sols, gels, aerosols, or emulsions, exhibiting the Tyndall effect. Colloids can be hydrophilic (water-attracting) or hydrophobic (water-repelling).
- 13.11: Exercises
- These end-of-chapter exercises are for practice to help you both understand concepts from the course and for practice for tests and exams.