270 likes | 533 Views
Ions in Water. Water. Expands when freezing – fish . Liquid Water. Ice. Water. Expands when freezing – fish Liquid at room temperature – H-bonding High specific heat (heat capacity) ↑ Weather High heat of vaporization – cooling ↑ High surface tension – capillary act.↑. Water.
E N D
Water • Expands when freezing – fish
Liquid Water Ice
Water • Expands when freezing – fish • Liquid at room temperature – H-bonding • High specific heat (heat capacity) ↑ • Weather • High heat of vaporization – cooling ↑ • High surface tension – capillary act.↑
Water • Expands when freezing – fish • Liquid at room temperature – H-bonding • High specific heat (heat capacity) ↑ - weather • High heat of vaporization – cooling ↑ • High surface tension – capillary act.↑ • An excellent solvent (polar) • Sometimes good? • Sometimes bad?
Solutions • Solvent – What things are dissolved in • Solute – What is dissolved • Solution – Combination of solvent and solute • A homogeneous mixture • Dispersed on a molecular scale • Ionic solute → Electrolyte • Molecular solute → Non-electrolyte
Solutions • Solubility • Insoluble • Miscible • Unsaturated • Saturated • Supersaturated • Solubility of gases in liquids • Soda pop
Dissolving vs. Melting • To a chemist, a salt is an ionic compound • H+ is not the positive ion (Cation) • OH- is not the negative ion (Anion) • NaCl melts at 801°C but will dissolve in water at room temperature (20°C) • Means that water really like ions • Cations surrounded by O’s • Anions surrounded by H’s
Salt Solutions • Conduct electricity – electrolytes • Lower the melting point of water • As much as 21°C • Salt on roads
Fluoride ion • Added to drinking water to decrease the number of cavities • Use is controversial • Aldshymers? • ADHD?
Moles • Not a furry animal or a turned spy in the CIA. • Like dozen, gross, ream, etc.
Moles • Not a furry animal or a turned spy in the CIA. • Like dozen, gross, ream, etc. • A mole has 6.02 x 1023 objects in it. • How do you count that many? • Very seldom is Avagadro’s number used • Instead of counting, you weigh a mole • Using molecular or atomic weights
Concentrations • Common is percent. • Chemists use molarity, M – moles/liter • Moles of solute per liter of solution. • If you need 3 moles of NaCl, how much of 2 M NaCl solution do you want? • How much solution should you make if you have .5 moles of NaCl and you want 2 M solution? • The concentration of H3O+ ion in pure water is 1 x 10-7 M.
H25 – C11 • 1, 2, 4 - 6, 9 - 13, 22, 23, 38, 40 - 44, 46, 47, 70, 78