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Unformatted text preview: when the solute and so lvent: Ø are similar substances Ø have similar intermo lecular forces of attractions Ø will disso lve in each other Ex: Ethyl alcoho l disso lves in water (Both are polar and both form H bonds) 5 solutesolute particles solventsolvent particles Chemistry 101 Chapter 12 CASE 2: The forces of attraction between solute and solvent particles The forces of attraction between solutesolute particles This happens when the solute and so lvent Ø are different in their chemical nature Ø have different type of intermo lecular forces of attractions Ø will not disso lve in each other Ex: CCl4 does not disso lve in Nonpolar mo lecule Associated through London forces H2O Polar mo lecule Associated through H bonds CONCLUSIONS: 1. “LIKE DISSOLVES LIKE” (Similar substances disso lve one another) 2. The more similar substances are in their chemical nature, the better they disso lve in each other. CASE 3: The forces of attraction between solute and solvent particles = The forces of attraction between solutesolute particles NOTE: There are no favored attractions Ø The natural tendency o f substances to mix (natural tendency toward disorder) will cause the solute to disso lve in the so lvent. Ex: Heptane (C7H16) disso lves in Hydrocarbon Nonpolar mo lecule London Forces Octane (C8H18) Hydrocarbon Nonpolar mo lecule London Forces 6 Chemistry 101 Chapter 12 SOLUBILITY OF IONIC SUBSTANCES IN WATER
· Solubilit y of io nic substances in water is determined by the relat ive strength of the: I. IONDIPOLE FORCES OF ATTRACTION
· These are attractions between solute ions and polar water mo lecules. H H O H2O H O H H H Na+ Cl- (s) O Na+ O H H H O H O Cl- O H H H H H H O Hydrated Na+ io n Hydrated Cl- ion · HYDRATION is the linking of the ions to the polar water molecules (an exothermic process)
· ENERGY OF HYDRATION is the energy given off when ions are hydrated. NOTE: 1. IONDIPOLE FORCES favor the solut ion process. The stronger the IONDIPOLE forces 2. The La...
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