1 ilo of the current topic: by the end of this topic, the student will be able to: identify...
TRANSCRIPT
![Page 1: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/1.jpg)
1
ILO of the current topic:By the end of this topic, the student will be able to: Identify different pH solutions.
pH and Buffers
![Page 2: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/2.jpg)
Our Goals for today
![Page 3: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/3.jpg)
1-Kw2-pH
Dissociation Of Water
![Page 4: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/4.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
Dissociation Of WaterDissociation Of Water
H2O H+ + OH-
Water has limited capacity to dissociate (ionize) into H+ &
OH-
![Page 5: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/5.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
Ka Is The Acid Dissociation Constant Of
Water
Since water is too little too little dissociated[H2O]
[H+] [OH-]= Ka
[H+] [OH-]So, Kw
[H+] [OH-]= Kw
Kw = The Ion Product Of Water
10-7 X 10-7 =Kw 10-14 mol/L
Since those values involving such –ve powers of 10 which is difficult to use in
calculations
So
Sorensen (1909) suggested that the
[H+]concentration of DILUTEDILUTE aqueous solutions
would be better expressed as PH valuePH value
![Page 6: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/6.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
What is the pH?
• The pH of a solution is the negative of the logarithm to the base 10 of its hydrogen ion concentration in (mol/L)
pH = -log[H+]
![Page 7: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/7.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
pH scale 2 3 4 5 6 7 8 9 10 11 12
neutral @ 25oC(H+) = (OH-)
distilled water
acidic(H+) > (OH-)
basic or alkaline(H+) < (OH-)
ranges from 0 – 14pH < 7 acidpH = 7 neutralpH > 7 base
![Page 8: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/8.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
P= -Log
H= H+ Concentration
pH= -log of H+ Concentration
![Page 9: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/9.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
P= -Log
OH= [OH- Concentration]
pOH= -log of [OH- Concentration]
[OH-] may be represented as pOH value
![Page 10: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/10.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
Since [H+] x [OH-] =10 -14
–log [H+] + -log [OH-] =14
i.e. pH + pOH =14
By –log of both sides
![Page 11: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/11.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
Q- What is the pH of 0.0001 N HCL sol.?A- [H+] = 0.0001 = 10-4 mol/L pH = - log 10-4 = 4Q - What is the pH of 0.001 N NaOH sol.? A- [OH-] = 0.001 = 10-3 mol/L pOH = - log 10-3 = 3 Since pH+ pOH=14 So, pH = 14 - pOH= 14 -3= 11
Problem 2Problem 2
![Page 12: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/12.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
What is the pOH of a 0.010 M solution of Ba(OH)2:
?A. 1.0
B. 2.0
C. 4.0
D. 5.0
Problem 3Problem 3
![Page 13: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/13.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
The pH of a sample of human blood was measured to be 7.41 at 25°C. Calculate pOH, [H+] and [OH-] for the sample.
Problem 4 Problem 4
Answer
pH + pOH = 14.00pOH = 14.00-7.4 = 6.6[H+] = antilog(-pH)= antilog (-7.41) = 3.9x10-8M[OH-] = antilog(-pOH) = antilog (-6.6) = 2.51 x 10–7 M
![Page 14: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/14.jpg)
1-Definition2-Properties3-Classification4-Neuteralization
Acids and bases
![Page 15: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/15.jpg)
Acids and bases
• Taste sour
• React w/ metals & carbonates-produce H gas
• Turn blue litmus paper red
• form hydrogen ions (H+) in water
• Taste bitter• Feel slippery• Don’t react w/
carbonates• Bases turn red
litmus paper blue.• form hydroxoxide ions
in water
Acids Bases
![Page 16: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/16.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
2-17
Acids cause H+ to increaseBases cause OH- to increase
![Page 17: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/17.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
Amphoteric SubstanceAmphoteric Substance
They can act as Proton DONORS DONORS with bases
& Proton ACCEPTORSACCEPTORS with acids
Eg. Amino acid –H2O
![Page 18: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/18.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
In dilute aqueous solution, as [H+] increases: A. pH decreases B. pOH increases C. [OH–] decreases D. all of the above
Problem 5 Problem 5
![Page 19: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/19.jpg)
Neutralization
HCl + NaOH → H2O + NaCl acid base water salt
• reaction between an acid & base
• produces water & a salt
an ionic compound
![Page 20: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/20.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
Strength Of Strength Of Acids Acids & & BasesBases
It depends on the degree of IonizationIonization in an aqueous solution
i.e.i.e.
The efficacy with which The efficacy with which
an an acid acid acts as a proton donor acts as a proton donor
& & a basea base acts as a proton acceptor acts as a proton acceptor
![Page 21: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/21.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
HA Let’s examine the behavior of an acid, HA, in aqueous solution.
What happens to the HA molecules in solution?
![Page 22: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/22.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
HA
H+
A-
Strong Acid
100% dissociation of HA
![Page 23: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/23.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
HA
H+
A-
Weak Acid
Partial dissociation of HA
Would the solution be conductive?
![Page 24: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/24.jpg)
HA
H+
A-
Weak Acid
HA H+ + A-
At any one time, only a fraction of the molecules are
dissociated.
![Page 25: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/25.jpg)
1-Calculation2-Uses
HENDERSON-HUSSELBALCH Equation
![Page 26: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/26.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology DepartmentHow can you calculate the How can you calculate the pH pH of of
Strong Acids & Bases ??Strong Acids & Bases ??
From the Molarity or Normality of them
i.e.i.e.
pH of Acid pH of Acid = - log of acid conc = - log of acid conc [H[H++]]
pH of Base pH of Base = 14 - pOH= 14 - pOH
![Page 27: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/27.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
pH pKa
= [HA] [A-]
+Log
HENDERSON-HUSSELBALCHHENDERSON-HUSSELBALCH Equation
![Page 28: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/28.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
USES OF USES OF HENDERSON-HUSSELBALCHHENDERSON-HUSSELBALCH
EquationEquation
1. For Calculation of pH of a weak Acid.
2. Preparation Of Buffer Of Known pH
![Page 29: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/29.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
When [A[A--]= [HA]]= [HA]
So PKa Of an acid is the pH at which
[The Acid conc.The Acid conc.] = [Its Conjugate base conc.Its Conjugate base conc.]
pH pKa
= + [HA] [A-]
Log
![Page 30: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/30.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
Summary
![Page 31: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/31.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
33
Strong AcidWeak Acid
Transfers all of its protons to waterTransfers only a small fraction of its
protons to water
Completely IonizedPartly Ionized
Ka largeKa is small
smallerpKAlarger pKA
Eg. HCl and H2SO4 Eg. Organic acids e.g. H2CO3
![Page 32: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/32.jpg)
1-Indicators2-pH Meter3-Titeration
Determining pH
![Page 33: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/33.jpg)
1-Indicator• Compound that changes color when in
contact w/ an acid or base
• They are weak acids
• ex. litmus paper
![Page 34: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/34.jpg)
• Red litmus paper
• Blue litmus paper
• universal indicators
•Red Cabbage Juice
![Page 35: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/35.jpg)
Mechanism of action of the litmus paper indicator
![Page 36: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/36.jpg)
Nameof indicator
Colour acid
Colour base
pH range
Methyl OrangeRedYellow 3 - 4
Bromothymol BlueYellowBlue6 - 8
PhenolphthaleinClearRed8 - 10
![Page 37: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/37.jpg)
Universal indicators
Universal indicators made by mixing several different indicators
Paper soaked in universal indicator pH paper
![Page 38: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/38.jpg)
pH meter determines the pH of a solution by measuring voltage between two electrodes that are placed in solution
Voltage changes as hydronium ion concentration in solution changes
2-pH meter
![Page 39: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/39.jpg)
1-Definition2-Principle of buffering3-Application
BUFFER
![Page 40: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/40.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
Buffers
It is a solution of A Weak Acid (H(H22COCO33))
& its Conjugate Base (NaHCO(NaHCO33))
Or Weak Base (NH(NH44OHOH) &
its Conjugate Acid (NH(NH44CL)CL)
![Page 41: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/41.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
BuffersIt resists changes in pH in a solution
when moderate amount of strong acids
or bases are added
Acid““HH22COCO33””
Conjugate base“NaHCO3”
OH-
OH-
OH-
OH-H+
H+
H+
H+
![Page 42: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/42.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
Principles of Buffering:AH ↔ H+ + A-
![Page 43: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/43.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
The Extent Of Buffer Capacity Depends on 3 factors
Any buffer exerts maximal buffering capacity when
the pH is equal to its pKa.
If [A-]= [HA ] i.e the acid is half dissociated (half-neutralization state)
Log [A-]/ [HA ] = log 1= zeropH = pKa + 0
![Page 44: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/44.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
pH= pKa 1
Is Considered as pH range
For
SATISFACTORY Buffering SATISFACTORY Buffering
CapacityCapacity
![Page 45: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/45.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
Physiological buffers1. H2CO3/ HCO3 (pKa= 6.1) This is the most important
buffer system in the body
2. H2PO4/ HPO4 (pKa= 6.8).
3. Plasm Proteins (20% of buffering capacity “NH“NH22+ + , ,
COOCOO--””))4. Hb. (60% of buffering capacity “Histidine”“Histidine”)5. Free amino acids
But Theoretically
Bicarbonate buffer Bicarbonate buffer is < efficient than is < efficient than Phosphate buffer Phosphate buffer
in intracellular fluid.in intracellular fluid.
![Page 46: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/46.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department
• The pKa of acetic acid is 4.76, its buffer mixture is most effective at pH:
• a) 2.3
• b) 4.5
• c) 3.7
Problem 6Problem 6
![Page 47: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/47.jpg)
pH = -log[H+]pOH= -log of
[OH]
pH + pOH =14pH= pKa +log [A-]
[HA-]
![Page 48: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/48.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology DepartmentLab activities include :
![Page 49: 1 ILO of the current topic: By the end of this topic, the student will be able to: Identify different pH solutions. pH and Buffers](https://reader033.vdocuments.us/reader033/viewer/2022051214/56649e165503460f94b00a05/html5/thumbnails/49.jpg)
Faculty of Medicine Ain Shams University
Medical Biochemistry & Molecular Biology Department