userdata-paziras-Chem101-Chap_12A

Thelargerthe energyrequiredto separatetheions theless

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Unformatted text preview: rger the ENERGY OF HYDRATION The Better the Solute Disso lves in Water ION­DIPOLE FORCES are inversely proportional to the size of the ion. The smaller the ion The stronger the ION­DIPOLE forces The larger the ENERGY OF HYDRATION 7 The Better the Solute Disso lves in Water Chemistry 101 II. Chapter 12 ION­ION FORCES OF ATTRACTION · These are attractions between cations (+) and anions (­) in the crystal lattice. · Separation of Ions from crystal lattice requires energy and is an endothermic process · LATTICE ENERGY is the energy required to separate the ions fro m the crystal lattice. NOTE: 1. ION­ION FORCES work against the solution process. The stronger the ION­ION forces 2. The larger the Energy required to separate the ions The less likely that solute will disso lve in water ION­ION FORCES : Ø are inversely proportional to the size of the ions. Ø are direct ly proportional to the charges of the ions CONCLUSIONS: 1. A so lute is likely to disso lve in water if: HYDRATION ENERGY LATTICE ENERGY 2. A so lute is not likely to disso lve in water if: HYDRATION ENERGY LATTICE ENERGY 3. The solution process is favored by: Ø any decrease in LATTICE ENERGY Ø any increase in HYDRATION ENERGY 4. Two main factors affect the LATTICE ENERGY and the HYDRATION ENERGY A) Size of the Ions: inversely proportional to both B) Charge of the ions: directly proportional to the LATTICE ENERGY 8 Chemistry 101 Chapter 12 FACTORS AFFECTING SOLUBILITY I. TEMPERATURE 1. Solubilit y o f Ionic Substances in Water KNO3 Solubility (g solute/100 g water) CuSO4 NaCl Ce2(SeO4)3 o Temperature ( C) · For the majorit y of Ionic Salts, the Solubilit y increases wit h temperature (the warmer the water, the better they disso lve). Except ions: Ce2(SeO4)3 , Ca(OH)2, CaSO4 2. Solubilit y o f Gases in Water · The Solubilit y o f gases decreases wit h increasing temperature (the colder the water, the better the gases dissolve). Examples are: Ø soda water keeps its carbonat ion (CO2 gas) better at low temperatures (at room temperature they go “flat” faster) Ø cold...
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