* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download chapter10 - AlvarezHChem
Survey
Document related concepts
Vapor–liquid equilibrium wikipedia , lookup
Ionic liquid wikipedia , lookup
State of matter wikipedia , lookup
Marcus theory wikipedia , lookup
Degenerate matter wikipedia , lookup
Spinodal decomposition wikipedia , lookup
Determination of equilibrium constants wikipedia , lookup
Chemical equilibrium wikipedia , lookup
Acid–base reaction wikipedia , lookup
Ionic compound wikipedia , lookup
Ultraviolet–visible spectroscopy wikipedia , lookup
History of electrochemistry wikipedia , lookup
Acid dissociation constant wikipedia , lookup
Debye–Hückel equation wikipedia , lookup
Nanofluidic circuitry wikipedia , lookup
Equilibrium chemistry wikipedia , lookup
Transcript
William L Masterton Cecile N. Hurley http://academic.cengage.com/chemistry/masterton Chapter 10 Solutions Edward J. Neth • University of Connecticut Concentration Units General Vocabulary: Solution – homogeneous mixture of solute and solvent Solute – the substance being dissolved Solvent – the substance doing the dissolving Electrolyte – a substance that conducts electricity when in solution - ionic Nonelectrolyte – a substance that does NOT conduct electricity when in solution - molecular Concentration Units • Molarity – (M) moles of solute per liter of solution • Molarity = moles of solute/liters of solution Example: What is the molarity of a solution made by dissolving 12.5g of oxalic acid (H2C2O4) in 456mL of solution? Dilution of Solutions M1V1 = M2V2 Example 10.1 Mass Percent • Percent by mass = (mass solute/mass solution) * 100 Molality • the number of moles of solute per kilogram of solvent Molality (m) = moles of solute/kilograms of solvent Example Conversions Between Concentration Units Start with a fixed amount of solution or solvent, see right column When the original concentration is Choose Mass percent 100 g solution Molarity (M) 1.00 L solution Molality (m) 1.00 kg solvent Example: Principles of Solubility • Factors that determine the extent to which a solute dissolves in a particular solvent: 1. The nature of solvent and solute particles and the interaction between them 2. The temperature at which the solution forms 3. The pressure, in cases of gaseous solutes Solute-Solvent Interactions • “Like dissolves like” = see table in notes • Polar solutes dissolve in polar solvents • Nonpolar solutes dissolve in nonpolar solvents • Nonpolar substances have poor affinity for water • Petroleum • Hydrocarbons (pentane, C5H12) • Polar substances dissolve easily in water • Alcohols, CH3OH • Solubility of alcohols decreases as the molar mass of the alcohol increases Solubility and Intermolecular Forces Effect of Temperature on Solubility An increase in temperature always shifts the position of an equilibrium to favor an endothermic process heat of solution > 0 heat of solution < 0 Figure 10.4 (Solubility Curves – pg 12) Effect of pressure on Solubility • Pressure has a major effect on the solubility of a gas in a liquid, but little effect on other systems • Henry’s Law - At low to moderate pressure, the concentration of a gas increases with the pressure Solubility Effects of Pressure Colligative Properties of Nonelectrolytes • The properties of a solution may differ considerably from those of the pure solvent • Some of these properties depend on the concentration of dissolved particles and not on their nature Boiling and Freezing Point • Boiling point elevation and freezing point lowering are both colligative properties T f mK f Tb mKb • Kf is the freezing point lowering constant • Kb is the boiling point elevation constant FPL and BPE Constants for Water • For water, • Kf = 1.86 • Kb= 0.52 Example 10.7 Molal Constants Determination of Molar Masses from Colligative Properties molality = moles of solute/kg of solvent MMsolute = grams/moles Example 10.9 Colligative Properties of Electrolytes When an electrolyte dissolves it breaks apart into ions. NaCl(s) Na+1(aq) + Cl-1(aq) So for every NaCl formula unit 2 aqueous ions are formed The formula is adjusted to reflect the number of ions: ∆T = k m i i = the number of ions formed Example 10.10 Solution Stoichiometry Example Solution Stoichiometry Example