Solutions • A. A solution is a uniform mixture of substances. • Types of solutions: • solid in liquid: NaCl in water Na+, Cl-, H20 • gas in gas: Air (N2, O2, Ar, etc) • solid in solid: Bronze (Cu and Sn) = an alloy • gas in liquid: CO2 in H2O • liquid in liquid: alcohol in H2O • liquid in solid: Hg in Ag
2. solute: substance being dissolved • the smaller amount • solvent: dissolves the solute • the greater amount • Ex. solution solute solvent • salt water • air NaCl water O2 N2
3. The most common solvent: water Water solutions are called aqueous (aq) Ex: In water: NaCl(s) Na+(aq) + Cl-(aq) solid water
Water H2O is polar. It has a + and – side: Attracts + charges - O H H + + Attracts - charges NaCl dissolves because: Cl + Na - - - + +
Ex. Surface tension occurs because water molecules attract each other.
Oil is nonpolar. H2O cannot pull it apart. It does not dissolve in water. Pentane: Diesel oil: Olive oil:
Rule: Likes dissolve likes: • 1. Polar substances dissolve polar ones. • Ex. NaCl in water • Nonpolar substances dissolve nonpolar ones. • Ex. Oil in turpentine • 3. Nonpolar ones do NOT dissolve nonpolar ones. • Ex. Water does not dissolve oil.
4. An electrolyte conducts electricity in a solution because the solute is ions. Ex: Na+ and Cl- are charged. They conduct.
4. An electrolyte conducts electricity in a solution because the solute is ions. Ex: Na+ and Cl- are charged. They conduct. Non-electrolyte: solution does not conduct electricity. Ex: Sugar (C6H12O6) is not charged.
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5. Particles in solution are too small to filter out, but they can be separated by other physical means. • Ex Desalination of sea water by distillation • When salt water is boiled, the salt remains. • The pure water can be condensed and used.