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This guide provides an in-depth explanation of solutions and solubility, including the definitions of solute and solvent, the concept of "like dissolves like," the factors affecting solubility, electrolytes and non-electrolytes, concentrations of solutions, colligative properties, and dilution techniques.
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Solution– homogeneous mixture of two or more substances in the same physical state • solute – substance being dissolved • Ex. salt, sugar • solvent – material in which solute is dissolved • Ex. water is the universal solvent
There is more solvent than solute in a solution. Ex. more water than salt Salt water
Soluble – able to be dissolved Ex. salt in water Insoluble – does not dissolve Ex. oil in water
“Like dissolves like” • Polar solutes will dissolve in polar solvents • Nonpolar solutes will dissolve in nonpolar solvents
Soluble – able to be dissolved Ex. salt in water Insolube – does not dissolve Ex. oil in water Nonpolar oil does not dissolve in polar water. Ionic dissolves in polar water.
Aqueous (aq) • When a material is dissolved in water vs.
Electrolyte • “dissociation” of ionic compounds (salts) into ions to conduct electricity when dissolved in water
Go to the web: • http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/thermochem/solutionSalt.html • http://www.northland.cc.mn.us/biology/Biology1111/animations/dissolve.swf
Non-electrolyte • Substance does NOT conduct electricity when dissolved in water • Includes all covalent compounds • Ex. sugar water
Concentrated vs. dilute • Lots of material dissolved vs. very little dissolved
Saturated – solution contains maximum amount of solute • Unsaturated – less than maximum • Supersaturated – more than maximum • Must be heated
Alloy • Two or more metals dissolved in each other • brass = Cu + Zn • sterling silver = Ag + Cu
Colligative Properties • Dependent on the presence of dissolved particles and their concentration • Boiling point elevation – solute particles increase boiling point • Freezing point depression – solute particles decrease freezing point
Go to the Web: • Boiling point elevation: • http://www.chem.purdue.edu/gchelp/solutions/eboil2.html • Freezing point depression: • http://antoine.frostburg.edu/chem/senese/101/solutions/faq/why-salt-melts-ice.shtml
Fixing Spaghetti • Example of boiling point elevation. • Adding salt requires the temperature to be greater than 100oC for the water to boil.
Salt on Roads • Example of freezing point depression. • The temperature must be lower than 32oF for the water on the road to freeze.
Vocabulary Word: • “stock solution” – a solution of a reagent at a standard concentration • Usually the highest concentration
Using a pipet • Use bulb to fill pipet • Use finger to adjust height of meniscus • Let off pressure to drain liquid