H1 h2 h3 h1 h2 hsoln h1 h2 h30 dissolving occurs

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Unformatted text preview: both polar or both non-polar), the intermolecular forces are similar. ∆H1 ~ ∆H2 ∆H3 ~ - (∆H1 + ∆H2) ∆Hsoln = ∆H1 + ∆H2 + ∆H3≈0 Dissolving occurs spontaneously due to an increase of disorder. The tendency of system to move towards disorder! disorder Spontaneity Spontaneity 1. Energy decrease 2. 2. Disorder (Randomness) increase Process Process in which the energy content of the system decreases tend to occur spontaneously! Spontaneity of of Processes Process occurring at a constant T in which the randomness in space of the system increases tend to occur spontaneously! Solubility, Saturated & Unsaturated solution Solubility: the maximum amount of Solute that will dissolved in a given amount of solvent at specific temperature. Saturated & unsaturated: differ in terms of the amount of solute in a solution. Unsaturated solution: can dissolve more solute : in a given amount of solvent at a specific temperature. Saturated - Have dissolved all the solvent allows. contains the maximum amount of a solute that will dissolve in a given solvent at a specific temperature. Supersaturated solution Supersaturated solution - contains more solute than presenting in a saturated solution at a specific T. An unstable state – temporarily dissolved too much, solute settles out when disturbed or over time. Factors Factors Affecting Solubility Solute-Solvent Interactions Polar liquids tend to dissolve in polar solvents The number of -OH groups within a molecule increases solubility in water Glucose Factors Factors Affecting Solubility Solute-Solvent Interactions Alcohol CH 3OH ( Methanol ) Solubility in water(mol/100g,20°C) Infinity CH 3CH 2OH ( Ethanol ) Infinity CH 3CH 2CH 2OH (Pr opanol ) Infinity CH 3CH 2CH 2CH 2OH ( Butanol ) 0.11 CH 3CH 2CH 2CH 2CH 2OH ( Penpanol ) 0.033 CH 3CH 2CH 2CH 2CH 2CH 2OH ( Hexanol ) 0.0058 CH 3CH 2CH 2CH 2CH 2CH 2CH 2OH ( Heptanol ) Miscible liquids: mix in any proportions proportions 0.0008 The number of carbon atoms in a chain affect solubility: the more C atoms the less solubility in water. The “Like dissolves like” Rule Two Two substances with similar intermolecular similar forces are likely to be soluble in each other be • Non-polar molecules are soluble in non-polar solvents NonnonCCl4 in C6H6 • Polar molecules are soluble in polar solvents C2H5OH in H2O • Ionic compounds are more soluble in polar solvents NaCl in H2O or NH3 (l)...
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