Chapter 11 Water and Solutions FYI: Household Water Usag

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Chapter 11Water and Solutions
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FYI Household Water UsageWhat does this tell
us?
Let nature water the lawn Stop Flushing the
John!
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FYI Water Supplies

• Surface water
• Streams, lakes and reservoirs
• Sediment, bacteria, possible pollutants
• Groundwater
• Generally cleaner
• Seepage from waste dumps, agriculture and
  industry
• Major pollution problems

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Structure of Water Molecules

• Polar covalent bonding
• Polar molecule dipole
• Oxygen negative center hydrogen end positive
• Hydrogen bonding between molecules
• Accounts for many physical properties.

Polarity animation
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FYI Properties of Water

• Universal solvent
• Dissolves most molecules
• Solid phase less dense than liquid
• Ice floats!
• Liquid phase most dense at 4ºC

Properties of water and surface tension animation
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The Dissolving Process

• Dissolving
• the process of making a solution
• Aqueous solution (aq)
• a solid, a liquid or a gas dissolved in water
• Simple rule Like dissolves like
• Polar substances
• Nonpolar substances
• Also think about a charge on an ion if they are
  involved.

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Liquid solvents and solids

• Like dissolves like
• Oil, grease are not soluble in water but salt is
• Ion-polar molecule force
• Hydration attraction of crystal surface versus
  water molecule
• Soap
• provides both polar and nonpolar environments.

Dissolution of a compound animation
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FYI Concentration of solutions

• Concentration - relative amounts of solute and
  solvent
• Relative terminology
• Concentrated - large amount of solute
• Dilute - small amount of solute
• More precise measurements of concentration

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FYI Concentration Measurements

• Concentration ratios
• parts per million (ppm) parts per billion (ppb)
• By volume or weight
• Salinity
• mass of salts dissolved in 1000 g of solution
• Molarity (M)
• number of moles of solute in one liter of
  solution

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Properties of water solutions

• Electrolytes
• Solutions of ionic substances
• Conduct electricity
• Nonelectrolytes
• Nonconductors
• Sugar and alcohol solutions
• Ionization
• Forming ions from molecules
• Can occur as polar molecules dissolve in water.

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Acids, bases and salts

• Known as the three classes of electrolytes
• Important in consideration of environmental
  quality
• Hard water - dissolved salts
• Soil acidity - plant health
• Water and air pollution - acid rain.

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Properties of acids

• Sour taste
• Litmus paper turns red
• React with active metals (magnesium, zinc) to
  release H2
• Neutralize bases, forming water and salts.

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Bases, alkaline substances

• Bitter taste
• Litmus paper turns blue
• Slippery on the skin caustic action converting
  tissue into soluble material
• Neutralize acids, forming water and salts.

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Explaining acid-base properties

• Acid - proton (H) donor when dissolved in water

• Base - proton (H) acceptor when dissolved in
  water

• Neutralization - result of mixing acids and bases

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Why would you need to add this to your pool very
carefully?
Fig 11.15
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FYI Strong and weakacids and bases

• Strong acids
• Ionize completely in water
• Nitric, sulfuric and hydrochloric acids
• Weak acids
• Partially ionized
• Acetic acid (vinegar)

• Strong bases
• Completely ionic in water, with hydroxide ions
• Sodium hydroxide
• Weak bases
• Partially ionized
• Ammonia, magnesium hydroxide

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The pH scale

• Pure water weakly ionized
• pH
• Power of ten notation
• Expresses H3O concentration
• Neutral solution pH 7
• Adding acid increases H3O ion concentration
  (lowers pH)
• Adding base increases OH- concentration (raises
  pH).

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FYI Properties of salts

• Any ionic compound except those with hydroxide or
  oxide ions
• Produced in acid-base neutralization
• Essential dietary source of electrolytes and
  minerals.

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Hard and soft water

• Aqueous solubility of salts varies
• Hard water
• Solutions of Ca2 and Mg2 ions
• Form insoluble compounds with soap
• Soap hard to lather
• Various removal methods for bicarbonate and
  sulfate salts including ion exchange.

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Water Softener System
Fig 11.17
http//h2oguy.com/treatment/howsoftworks.html
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4-Step Process
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