Chapter 6 Notes Solutions, Acids, and Bases

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Chapter 6 NotesSolutions, Acids, and Bases
Teacher discussing at length in class...
Stomach acid in there

• Basically, the solution to this chapter is
  paying attention to terms and concepts, the
  teacher retorted acidly.

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6.1 Heterogeneous mixturesmixtures that arent
the same throughout (can see their parts).

• Three kinds-suspensions, colloids and emulsions.
• Suspensions- mixture (cloudy) that looks
  well-blended when stirred, but it settles out in
  layers when not agitated.
• Examples orange juice, muddy water, flour in
  water.
• Particles are large and eventually gravity pulls
  them down to the bottom.

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• Colloids- mixture of very tiny (still
  cloudy)particles spread out in another substance
  that do not settle out.
• Particles are smaller (1 to 100 nm)
• Examples egg white, paint, blood, gelatin,
  whipped cream, marshmallows, fog, smoke.
• Particles are very small, gravity isnt strong
  enough to make them settle out.

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• Many substances can be in mixtures (see examples
  previously). Liquids mixed w/gases, solids in
  liquids, etc.
• Liquids can be mixed into liquids as well. When
  two liquids wont mix, they are said to be
  immiscible . They separate in layers (oil
  water).
• If mixed anyway into tiny beads of liquid
  w/liquid, a kind of colloid called an emulsion
  develops.
• An emulsifier is a substance that helps keep
  emulsion mixed

• Examples mayonnaise, cream, etc.
• Emulsions are mixtures of immiscible liquids that
  are spread throughout each other.

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Homogeneous mixtures are uniform, dont just
look uniform. Pure substances are blended evenly
throughout.
Example Salt (the solute) dissolves completely
in water (the solvent) to the molecule level to
make a solution of salt water.

• 1 main example Solutions are a homogeneous
  mixture of two or more substances completely
  dissolved in each other (to molecule level).
• Two main parts
• Solvent is the substance that does the dissolving
• Solute is the substance dissolved.

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Solutions can come in many forms

• Two or more liquids that are miscible (mixable)
  in each other can make a solution.
• Ex acetic acid water vinegar, and alcohol
  water make a solution.
• These can be separated by distillation. They
  have different boiling points, so one can be
  boiled and leave the other behind.
• Chromatography (p.191) is used to separate
  difficult mixtures.

Gases can dissolve in each other (atmosphere),
gases can dissolve in liquids (Dr.Pepper)...
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6.2 Dissolving and Solubility

• Individual molecules break away from a substance
  and mix completely by diffusion (dissolve)
• Solutes with large surface areas dissolved faster
  (more solute/solvent interaction, fig.6-8) (Ex.
  powdering up a pill)
• Stirring or shaking a solution speeds dissolving
  (moves dissolved stuff away from solute, and
  mixes (stirring sugar into tea)

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• Solutes dissolve faster in hot solvent (particles
  are moving faster, so dissolve quicker)(ex
  Sugar diss. easier in hot tea than cold)
• Not every substance dissolves.
• Substances that dissolve are soluble.
• Substances that dont dissolve are called
  insoluble.
• Substances that dissolve a little are called
  partly soluble.
• Water is sometimes called the universal solvent,
  b/c many things dissolve in it, and its common
  (2/3 of earths surface, 3/4 your body)

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• Why is water such a good solvent? Its structure
  (uneven elements/e- sharing) makes it slightly
  positive and negative at either end. (fig.6-11)
  It is said to be polar.
• Substances that dissolve in water are also polar
  and tend to interact with waters charges.
• Like dissolves like polar things dissolve in
  water, nonpolar things, particularly oily things,
  like gasoline, dont.
• Substances like gasoline are soluble in oils and
  other nonpolar substances.

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Concentration- quantity of solute dissolved in a
given quantity of solution.

• Concentration essentially is how much stuff you
  can dissolve in how much solvent.
• A lot of stuff dissolved is a concentrated
  solution.
• A little stuff dissolved is a dilute solution.
• How much stuff you can get dissolved depends on
  the substances solubility (the max amount it can
  hold at that temperature).

• A saturated solution one that is holding as much
  as it can at that temp. No more can dissolve, it
  would just settle out.
• Unsaturated- it could hold more than it is.
• Supersaturated- a saturated solution at a higher
  temp is cooled, causing some subst. to hold more
  than normal. Unstable, may crystallize out if
  disturbed (p.197).

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Measuring concentration Molarity

• If you need to describe a solutions
  concentration accurately (not just saturated,
  unsaturated)several ways.
• Grams solute per 100g of solvent.
• Mass percent grams of solute per 100g of
  solution.
• Ex. Of mass percent 5 solution of NaCl is made
  by dissolving 5g NaCl in 95g of H2O.
• Concentration is also in Molarity.
• Molarity (M) moles of solute/liters of solution
  
• Ex 2.0M of NaCl 2mole NaCl in 1 liter of H2O

Called a 2 molar solution of NaCl
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Intermission
Time to take a little break...
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6.3 Acids, Bases, and pH

• Acids- substances that donate H ion to form
  hydronium ions, H3O, when dissolved in water.
• Taste sour, turn indicator paper red. Pickles
  (acetic acid), lemons, fruit (citric acid),
  conduct electricity.
• Indicators are substances that can change
  color(reversible process) to show concentration
  of hydronium ions.
• Strong acids ionize completely (all Hpossible)
  and have stronger acid and electric effects
  (nitric, sulfuric, hydrochloric acids).
• Nitric acid water hydronium ion
  nitrate ion
• Weak acids dont ionize completely/have less
  effect.(acetic, formic, citric acids)
• Acetic acid water hydronium ion
  acetate ion

Nearly all converts to H
Only some converted to H
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Bases

• Base substance that contains OH- ions or reacts
  with water to make such ions.
• Slippery, taste bitter, conduct electricity,
  change indicator color (blue), can burn.
• Ex KOH (drain cleaners), ammonia, etc.
• Like acids, some ionize completely and are called
  Strong bases. Others dont and are called Weak
  bases. Strong bases have strong effects and
  conduct electricity well, weak bases dont.
• pH - measure on hydronium ion concentration in a
  substance. Tells from 0 to 14 how basic or
  acidic something is.

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pH Scale
0 1 2 3 4 5 6 7 8 9
10 11 12 13 14
Apple juice
Pure water
Baking soda
Battery acid
Household ammonia
Drain cleaner
Black coffee
Stomach acid
handsoap

• pH measures hydronium conc., but also indicates
  hydroxide concentration.
• On the scale, 7 is neutral (water,salts).
• Anything above 7 is increasingly basic (14 most
  basic), anything below 7 is acidic (most acidic
  0).

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Are these acids or bases?
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• The pH scale is registered in powers of 10. Note
  (prev.slide) that apple juice is 102 or about 100
  times as acidic as coffee.
• Acid hydronium ions and base hydroxide ions react
  to form water. Hence St.acids and bases may be
  combined (neutralization reaction) to make
  neutral water and some leftover salts (if the
  amounts are equal).
• Salts produced are cations bonded to anions (see
  p.205)

Note Do not combine ammonia and bleach
(produces poisonous chloramine), or vinegar and
bleach (produces poisonous chlorine gas).
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6.4 Acids and Bases in the Home

• Cleaning products- Soaps dissolve in oil and
  water. They are emulsifiers that make them blend
  together, allowing the water to clean and carry
  away oils/greases as well as other substances.
  Soaps are usually made of an animal fat or oil
  mixed with KOH or NaOH (more, see p.208).
• Soap is useful for cleaning, but doesnt work
  well in hardwater (where lots of ions).
  Detergents are emulsifiers that dont react with
  these ions to form soap scums (sulfonate groups
  instead of carboxylate groups) (see p.208).
• Ammoniamixture of ammonia, ammonium, water, and
  OH- (see p.209). OH- works similarly to cause
  greasy dirt to form an emulsion with water.

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• Disinfectants- kill harmful bacteria or viruses.
  Bleach - disinfectant, sodium chlorite, NaClO2,
  or sodium hypochlorite, NaOCl, w/H2O
• Some hypochlorite ions, OCl- react with water to
  make hypochlorus acid, HOCl, and hydroxide (OH-)
  ions. The hydroxide makes the slippery basic
  feel of bleach, the hypochlorous acid kills the
  germs. Bleach also oxidizes stains, making them
  white (bleaching them).
• Other household acids bases-
• clothes dye sulfonic or carboxylic acids,
  antacid tabletssodium hydrogen carbonate,
  magnesium hydroxide-basic to counteract an overly
  acidic stomach
• Healthcare products are often acid or base
  ascorbic acidvitamin C-body growth and repair,
  acetyl-salicyclic acidaspirin
• Acids in the kitchen lemon juice keeps fruits
  from browning (stops oxidation) and vinegar or
  wine tenderize meat b/c the acid denatures
  proteins acids curdle milk to make yogurt
• Bases in the kitchen- baking soda and powder for
  baking, nearly all cleaning products.

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The End
of the rainbow, of course...