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H2O F-^ H^
+ OH
OH bonds are polar and can dissociate heterolytically
Bond breaking in^ which^ the^ bonding^ electron^ pair^ is^ split
unevenly between^ the^ products^ Hydronium ion^ gives^ up^ a^ proton
Products are^ a^ proton^ (ti)^ and^ a^ hydroxide^ 10h^ (01-1)
Hyo, _ H
Proton (^) hop
I
1-11-1107 (^) H Dissociation of^ water^ is^ a^ rapid^ reversible^ process^ H,^ yy,#
"
H V
Most water^ molecules^ remain^ un
- (^) ionized,thus (^) pure water has μ /^ ' μ = - Go-H
very low^ electrical^ conductivity^1
H H The (^) equilibrium is^ strongly^ to^ the^ left^ 110W^ Kea)^ μ , 0-1-
The extent^ of^ dissociation^ depends^ on^ the^ temperature^
μ / protons do^ not^ exist^ freely in^ solution 21-1,0 1- "
OH
_
They are^ immediately^ hydrated^ to^ form
- ⑨A• +^ ¥81k• ←^ ⑨@• +^ ⑨a (^) hydronium 10ns^ (1-130-1)
keg can^
be determined experimentally , it^ is^ 1.8*10-1%1^ at^ 25°C^ Keg= [HHj ] [1-1,0] can^
be determined from water^ density , A
hydronium ion^ is^ a^ water^ molecule^ with
1+1555.5119 a^ proton^ associated^ with^ one^ of^ the^ nonbonding
electron pairs tonic (^) product Of^ water:^ Hydronium ions are solvated (^) by (^) nearby water molecules Kw= (^) keg
- [1-10]=[1-1-1] [OH-7=1.1- '
"M
2 The covalent and hydrogen bonds are
interchangeable
In pure water^ ,^ [H+]^ =^ [01-1]=10-74^ allows^ for^ an^ extremely^ fast^ mobility
of protons in^ water^ 111A^ ''^ proton^ hopping^.
"
0 IN^ HCl
pH:
Gastric Juice
2 Lemon Juice
Kw=[H "
] [OH^ -1=1.10-11%
} [g☆aˢ'ⁿ9lY^ Cola (^) , vinegar
4 acidic^ Red^ wine
- log [H+] - log [01-5]=+14^ Beer (^5) Black coffee
PH +^ POH =/^4
7 N☒7dral
Milk, Saliva
Human blood, tears
pH and^ POH^ must^ always^
add up -
μ
seawater> egg white
9 Increasingly solution of baking
In neutral^ """'^ "^ '^ """^ "
"" and^ """^ "^ >
§,ggÑ% """"""°"
pH can^ be^ negative^ ([1-1-1]=614 Household ammonia
13 Household^ bleach
pH Scale^14 IMNAOH [H
- ] (M)^ pH^ [OH - JCM) (^) Poti Strong Acids
10° (l) 0 10
-14 (^14) iM¥% THEE^ TREE^ THAT THE:P , 10 -^11 -13 13 ' ii. a (^) ion n^ €¥EE±€^ (÷É¥?-€¥¥EEÉ^ E€•?-€#E€E÷
10-3 Hydrochloric^ Nitric
μ,,^ , Hydrolodlc Perohloric Chloric
3 10-11 It Acid Acid Acid Acid
10
- (^) " ° 10 Dissociate completely^ into^ their^ 10ns^ in^ water,^ yielding 10
- 5
10 -4^9 one or more proteins^ per^ molecule
10
10
" > Weak Acids
io-oc.MN#TFcqM.qTFF.IF MMF•^ 9M¥ ' °^ " a :} ii. s 105 " 10 €¥÷E€¥€÷E^ ☒E¥E¥¥¥:#^ €¥÷ET¥E¥^ ÷÷ÉE¥÷
Sulfurous (^) Methanol C (^) Phosphoric μ ,^ ,^ ,
Hydrofluoric
" (^) " "
/I
10-3 3 Acid^ Acid^ Acid
""""ˢ Acid
' (^) "
12 10-2 2 Do Not Dissociate completely into their 10ns In water,
_' (^1) yielding one or more proteins^ per^ molecule
10 -14^14 10011 ) 0
Most organic acids^ are^ weak^ adds
significant in^ biological^
functions
Buffers -_ Mixtures (^) of Weak Acids and Their (^) Conjugate Base
☐""" """ """ "^ °"^
7-
μj"÷¥
At pH =^ pka ,there^ is^ a^50 :^50 mixture^6
◦f^ "'d^ and^ ◦""°"^ f""^ "^ + " (^) "MP°"^ᵈ (^5) =
__Ñ%⑧G⑤÷¥
-^ "^ "^ "
P " 4 - Buffering ••Éa= .>^ , re (^) "" Buffering (^) capacity of^ acid^ /Anton^ system^ IS^3 _ ↓_pH 3.
greatest at^ pH^ =pKa
2 ¥¥oH.com^ =
guy,,.mg aapa,,,y^ ,,^ ,,,,^ wn,,^ ,
,, (^) p,^ g,,,,,^ g
, ,¥*,q_
from pKa by more^ than^ I^ PH^ UNIT^ 0.10.2^ 0.30.4^ 0.50.6^ 0.70.8^ 0.9^ 1.
OH ._ added^ (equivalents)
Henderson -^ Hasselbatch^ Equation^ :^ O 5/0 (^) 100% Percent titrated HA (^) 1-i'+^ A-
ka=[H¥÷}
Biological Buffer (^) Systems
[H+]- - ka
{]
Maintenance Of^ Intracellular^ pH is^ vital^ to^ all^ cells
↓ (^) Enzyme - catalyzed reactions have^ optimal pH
- 10g [H+]= - tog ka- 109 {H,fg solubility^
of polar molecules depends on^ H^ -^ bond^ donors^ and^ acceptors
Equilibrium between^ CO2^ gas^
and dissolved^ Hcoj depends^ on^ pH ↓ ↓ (^) Buffer (^) systems in (^) vivo are (^) mainly based on pH =pKa-110g [^ phosphate^ ,^ concentration in^ mini^ molar^ range [HA]^ bicarbonate^ ,^ important^ for^ blood (^) plasma histidine (^) , efficient buffer^ at^ neutral^ pH Buffer (^) Systems in^ vitro^ are^ often^ based^ on^ sulfonic
acids of cyclic amines
HEPES
PIPES HO
CHES
N N
SO
,
Na
