Solutions and Acids and Bases No Pics
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Transcript of Solutions and Acids and Bases No Pics
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Solutions and Acids and
Bases
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Types of Attractions
Ionic
Covalent
Hydrogen
Van der Waals Forces
Intermolecular force of attraction
Due to uneven sharing of electrons in covalent bonds
Slight attraction between oppositely charged regions of molecules thatare closely packed together
Holds large molecules together
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Hydrophilic and HydrophobicSubstances
A hydrophilic substance is one that has anaffinity (likes!) for water
A hydrophobic substance is one that doesnot have an affinity (does NOT like; scared
of) for water
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Mixtures physically, not chemically mixed compounds
Not necessarily evenly distributed
Homogenous Evenly distributed
Cannot see the different parts
Heterogenous Not uniformly distributed
you can see the parts Solution
Homogenous Mixture components are uniformly distributed
Solutes and solvents
Ex. Salt water Suspension
Mixture of water and non-dissolved material
Some of the most biologically important substancesare both solutions and suspensions
Ex. blood
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How water acts in solution
Occasionally a water moleculedissociates (breaks up) into ions H2O H+ + OH-
This happens to every one watermolecule in a million in pure waternot very common
The H+ immediately reacts with
another water molecule in thesolution to make a HYDRONIUM ionH30+
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Acids and Bases
What do you know?
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Acids
An acid is any substance that increases the H+
concentration of a solution ADDS H+ ions to water
taste sour
turn cabbage juice red
turn blue litmus paper red
Strong acids (LOW pH) Dissociate completely in water
Adds LOTS of H+ ions
Hydrochloric acid HCl
HCl H+ and Cl-
Weak Acids (pH slightly below 7) Partially dissociate in water
Only add a little bit of H+ ions
Coffee, tomato juice, acetic acid
H O//|
-- H C C | \\
-H O
CH3COOH = CH
3COO- + H+
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Bases A base is any substance that reduces the H+ concentration
of a solution
ADDS HYDROXIDE ions (OH-) to water OH- ions bind to any free H+ ions to makea molecule of
water
This does what to the concentration of H+ ions ion thewater?\
DECREASE H+ ion concentration, therefore, making it basic
Characteristics: taste bitter
feels slimy
turns cabbage juice yellow, green or blue depending uponthe solution concentration
turns red litmus paper blue
Strong Bases (pH High- close to 14) Completely dissociate in solution
Adds LOTS of OH- ion to solutions
NaOHsodium hydroxide NaOH Na+ and OH-
Weak Bases
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http://www.chem4kids.com/files/art/ph_scale.gifhttp://www.chem4kids.com/files/art/h_oh_ph.gif -
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Strong Acids and Bases
-H C l h yd ro ch lo rica cid
H N O 3 - nitricacidH 2SO4 - sulfuric
acid
-HBr hydrobromicacid-HI hydroiodic acid
HClO4 - perchloricacid
-LiOH lithium hydroxide-NaOH sodium hydroxide
-KOH potassium hydroxide-RbOH rubidium hydroxide-CsOH cesium hydroxide
ISSOCIATE COMPLETELYISSOCIATE COMPLETELYhat do you notice?hat do you notice?
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The pH Scale
The pH of a solution is determined by therelative concentration ofhydrogen ions H+ So it is really measuring how acidic something is
formula is..
pH=-log[H+] Negative means opposite, this is why a low pH has
MORE H+ ions
[x] means concentration
Acidic solutions have pH values less than 7 More H+ ions
Basic solutions have pH values greater than 7 More OH- ions, less H+ ions
Most biological fluids have pH values in theran e of 6 to 8
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LE 3 8
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LE 3-8 H Scale0123456789
1011121314 ve ncleaner
ouseholdbleach
ousehold ammoniailk ofmagnesia
Seawater
ure waterum an b loo d
UrineRainwater
lackcoffeeomatojuice
, ,inegar beer,in ecola
igestive( )tomach,uice lemonjuice
atteryacid
Neutral[H+] = [OH ]
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Buffers
The internal pH of most living cells mustremain close to pH 7
Buffers are substances that minimizechanges in concentrations of H+ and OH-
in a solution Weak acids are a buffer for strong bases
Weak bases are a buffer for strong acids
Most buffers consist of an acid-base pair
that reversibly combines with H+
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Acids and Bases in the LivingThings
Changes in concentrations of H+ andOH- can drastically affect thechemistry of a cell
When you breath
CO2 + H2O H+ + HCO-3
Carbon dioixde water hydrogen ion bicarbonate ion
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The Threat of AcidPrecipitation
Acid precipitation refers to rain, snow, orfog with a pH lower than 5.6
Acid precipitation is caused mainly by themixing of different pollutants with water
in the air Acid precipitation can damage life in lakes
and streams
Effects of acid precipitation on soilchemistry are contributing to the declineof some forests
LE 3 9
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LE 3-9
01234567891011121314
Morebasic
Normalrain
MoreacidicAcidrain