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Water & Solutions. Water (H 2 O) 2 hydrogen atom 1 oxygen atoms Covalent bond Essential to all forms of life 70% of the human body ( by weight ) Covers ¾ of the Earth Multiple uses Drinking Cleaning, bathing, etc. Water & Solutions. Properties of Water Acts as a solvent
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Water & Solutions • Water (H2O) • 2 hydrogen atom • 1oxygen atoms • Covalent bond • Essential to all forms of life • 70% of the human body (by weight) • Covers ¾ of the Earth • Multiple uses • Drinking • Cleaning, bathing, etc.
Water & Solutions • Properties of Water • Acts as a solvent • The ability to dissolve molecules • Liquid phase has a greater density (g/cc) than in a solid phase • Ice floats • High specific heat (amount of heat/energy needed to raise 1g 1 degree C ) • Needs more energy to heat it • What is the application of this concept? • Hint: 3/4 of the earth is covered w/ water • High latent heat (heat absorbed/released by 1g to change phase) • Dissipate large amounts of heat and loose a small amount of water
Water & Solutions • Structure of the Water Molecule • 2 hydrogen atoms & 1 oxygen atom • Covalent bond or ionic bond ???????? • With water – the shared electrons spend more time with the O atoms. • Polar molecule forms • Water is a hydrogen bond - or - because of the special way in which the oxygen atom and hydrogen bond – water is a very unique substance with very unique characteristics – ie the shape of snowflakes
Water & Solutions • Solvent – the component present in the larger amount. • Water • Solute – the component that is dissolves in the solvent. • Sugar
Water & Solutions • Dissolving Process • Solution • Homogeneous mixture • Saturated & solubility (or what came first the chicken or the egg) • Solubility – the ability to dissolve something • The attraction between the molecules or ions of a solvent and solute determines solubility • “Remember to wash your hands” • Fig 11.5 – p. 280 • A chemical tug-of-war
Water & Solutions • Concentration of Solutions • Concentrated vs diluted • The amount of solute in the solution • Concentration ratios • Parts per million (ppm) • Parts per billion (ppb) • Sea water – 35 parts / 1000 • How concentrated a solution is - is determined by the solutes solubility • A key factor of solubility is TEMPERATURE • Increase the temp – the greater the solubility • Sugar in your tea, coffee, or Kool-Aid
Water & Solutions • The concept of saturation • The limit at which the solute will dissolve • Dissolving is still taking place – you just can not see it.
Water & Solutions • Boiling & Freezing Point of Water • Boiling Point • 100 degrees C • 212 degrees F • Boiling, and the effect of atmospheric pressure • Two forces working against each other • Vapor pressure & atmospheric pressure (14.7 lbs / sq. in) • What is the principle behind a “pressure cooker”? • Freezing Point • 0 degrees C • 32 degrees F • “Fire up the salt trucks - winter is coming !!!!!”
Water & Solutions • Acids & Bases • A function of the of the number of hydrogen atoms • Acid – able to donate a H ion • Base – able to accept a H ion • pH Scale • If pH < 7.0 Acid • If pH > 7.0 Base • “Red eyes”