Water & SolutionsWater (H2O)

2 hydrogen atom1 oxygen atomsCovalent bondEssential to all forms of life

70% of the human body (by weight)Covers ¾ of the EarthMultiple uses

Drinking Cleaning, bathing, etc.

Water & SolutionsProperties 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/ waterHigh latent heat (heat absorbed/released by 1g to change phase)

Dissipate large amounts of heat and loose a small amount of water

Water & Solutions

Water & SolutionsStructure of the Water Molecule2 hydrogen atoms & 1 oxygen atomCovalent 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 & SolutionsSolvent – the component present in the larger

amount.Water

Solute – the component that is dissolves in the solvent.Sugar

Water & SolutionsDissolving 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. 280A chemical tug-of-war

Water & SolutionsConcentration 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 & SolutionsThe concept of saturation

The limit at which the solute will dissolve Dissolving is still taking place – you just can not see

it.

Water & SolutionsBoiling & Freezing Point of Water

Boiling Point 100 degrees C 212 degrees F

Boiling, and the effect of atmospheric pressureTwo 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 & SolutionsAcids & BasesA function of the of the number of hydrogen

atomsAcid – able to donate a H ionBase – able to accept a H ion

pH ScaleIf pH < 7.0 AcidIf pH > 7.0 Base

“Red eyes”