Aqueous Systems The wonder of water Water as

Aqueous Systems The wonder of water

Water as a liquid • High surface tension and low vapor pressure are due to hydrogen bonding

Water as a solid • Water actually expands slightly as the tendency to actually arrange in a lattice moves the molecules farther apart than when in the liquid state

Terminology • Solvent: the dissolving medium • Solute: that which is dissolved • Aqueous solution: solution with water as the solvent • Solvation: the process of a solute dissolving, becoming surrounded by solvent molecules

Electrolytes and nonelectrolytes • Electrolytes: compounds, when in an aqueous state or molten, that will conduct electricity; this occurs because the ions of the compound become mobile. • Non-electrolytes: see above. Basically, molecular compounds that are not composed of ions. • Strong vs. weak: degree of ionization

Hydrates • Compounds with “bound” water as part of the • • formula. Example: Cu. SO 4· 5 H 2 O Example: Mg. SO 4· 7 H 2 O Efflorescence: the process of losing this water Hygroscopy: the process of removing water from the atmosphere, absorbing it. Compounds like this are hygroscopic or deliquescent (will form solutions).

More Aqueous systems • Suspensions: a solution where the particles can separate over time • Colloids: heterogeneous mixture whose particles are smaller than a suspension and display the Tyndall Effect, that is they scatter light