Acids and Bases - JU Med: Class of...
Transcript of Acids and Bases - JU Med: Class of...
![Page 1: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/1.jpg)
Acids and Bases Dr. Diala Abu-Hassan, DDS, PhD
MD summer 20141Dr. Diala Abu-Hassanscience.lotsoflessons.com
![Page 2: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/2.jpg)
Required material and further reading
Required:Handout Text books:Biochemistry. Campbell Chapter 2Fundamentals of General, Organic, and
Biological Chemistry. McMurry. Chapter 10 softcopy will be sent
2Dr. Diala Abu-Hassan
![Page 3: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/3.jpg)
Outline
• Introduction- The Science of Biochemistry
• Definitions of acids and bases• Acid and base strength • The dissociation constant• Conjugate pair strength• Water dissociation
3Dr. Diala Abu-Hassan
![Page 4: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/4.jpg)
Garret et al 4
Biochemistry is the science concerned with studying the
various molecules that occur in living cells and organisms and
their chemical reactions.
What is Biochemistry?
Dr. Diala Abu-Hassan
![Page 5: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/5.jpg)
1. Biochemistry is an intrinsically beautiful and fascinating body of knowledge. “Lubert Stryer”Because it unravels the details of the most fundamental processes in biological systems.
2. Biochemistry massively influences medicine and treatment development, ex. sickle-cell anemia, cystic fibrosis, hemophilia, etc.
3. By advances in biochemistry, researchers can tackle many questions in biology and medicine, ex. Biochemical changes in diseases, causes of diseases, lab tests..etc.
Why Biochemistry is important to Human Biology?
5Dr. Diala Abu-Hassan
![Page 6: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/6.jpg)
When we unravel the molecular and biochemical details of biological molecules:
1. Molecular and biochemical basis of diseases become clear.
2. Manipulate the biochemical processes and simulating them in vivo and in vitro.
3. Molecules of life can be prepared on the bench
Benefits of studying biological systems at the molecular and biochemical level
6Dr. Diala Abu-Hassan
![Page 7: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/7.jpg)
What makes biomolecules special?
Campbell, 6th edition 7
-The cellular apparatus of living organisms is made up of carbon compounds.
Dr. Diala Abu-Hassan
![Page 8: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/8.jpg)
Dr. Diala Abu-Hassan 8
Different Definitions of Acids and Bases
- Arrhenius
- Bronsted-Lowry
- Lewis
![Page 9: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/9.jpg)
Arrhenius Definition of Acids and Bases and Their Reactions
Arrhenius Acids and Bases Acids are • Acids in H2O are H+ donors• Bases in H2O are OH- donors
Neutralization of acids and bases produces salt and water.
NaOH H2O Na+ + OH-
HCL H2O Cl- + H+
H+ + H─ Ö: H3O+
│H
Drawbacks:1. Reactions has to happen in aqueous solutions2. H3O+ is released but not H+
Arrhenius 1903
Nobel Prize
9Dr. Diala Abu-Hassan
![Page 10: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/10.jpg)
Bronsted-Lowry Acids and Bases (1923)• Acids donate H+
• Bases accept H+ (non-bonding pairs)
B: + H ─ A BH+ + A-
Bronsted-Lowry Definition of Acids and Bases and Their Reactions
Base Acid Acid Base
Conjugate acid-base pair
Conjugate acid-base pair
10Dr. Diala Abu-Hassan
![Page 11: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/11.jpg)
11
• Acids accept electrons• Bases donate electrons (non-bonding pairs)
BF3 + NH3 F3B NH3
Acid base
Lewis Definition of Acids and Bases and Their Reactions
::
Dr. Diala Abu-Hassan
![Page 12: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/12.jpg)
Common Acids
• HCl- hydrochloric- stomach acid• H2SO4- sulfuric acid - car batteries• HNO3 – nitric acid - explosives• HC2H3O2- acetic acid - vinegar• H2CO3-carbonic acid – sodas• H3PO4- phosphoric acid -flavorings
12Dr. Diala Abu-Hassan
![Page 13: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/13.jpg)
Common Bases• NaOH- sodium hydroxide (LYE) soaps, drain
cleaner• Mg (OH)2 - magnesium hydroxide-antacids• Al(OH)3-aluminum hydroxide-antacids,
deodorants• NH4OH-ammonium hydroxide- “ammonia”
13Dr. Diala Abu-Hassan
![Page 14: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/14.jpg)
Water as both an acid and a base
CH3COO- + H2O CH3COOH + OH-
H2O + HCl H3O+ + Cl-
base acid acid base
base acid acid base
HA + H2O H3O+ + A-
(strong acid) (weak base)
HA + H2O H3O+ + A-
(weak acid) (strong base)
Strong acid + strong base weak base + weak acid
14Dr. Diala Abu-Hassan
![Page 15: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/15.jpg)
Amphoterism - an ion or molecule can act as an acid or base depending upon the reaction conditions
H2O + NH3 NH4+ + OH-
Water in NH3 serves as an acid
acid acid basebase
Water in acetic acid serves as a base
H2O + CH3CO2H H3O+ + CH3CO2-
base acid acid base
Conjugate acid of H2O
Conjugate base of acetic
acid 15Dr. Diala Abu-Hassan
![Page 16: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/16.jpg)
Molarity: the number of moles in a liter of solution
Unit: Mole/Liter = M
mM = 10-3 M, uM = 10-6 M
Symbol: [X]
Concentration =
Dissolve 2 moles of glucose in 5 liters of H20. what is the concentration?
[Glucose] = 2/5 = 0.4 M
16Dr. Diala Abu-Hassan
Measuring concentrations
Amount of soluteAmount of solvent
![Page 17: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/17.jpg)
Acid and Base Strength• Some acids can cause burns if come in contact with skin,
other acids are safe. why?• How easy can the acid produce proton
– Strong acid: gives up H+ easily (100% dissociated in water)
HCl H+ + Cl-
– Weak acid: gives up H+ with difficulty ( less than 100% dissociated)CH3COOH H+ + CH3COO-
![Page 18: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/18.jpg)
Acid dissociation constant, Ka
O][HA][H]][AO[HK
2
3a
−+
=
[H2O] = 55.5 M and is constant in all equations
18
HA + H2O H3O+ + A-
[HA]]][AO[HK 3
a
−+
=
Dr. Diala Abu-Hassan
– The general ionization of an acid is as follows:
So the acid dissociation constant is as follows:
![Page 19: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/19.jpg)
Acid dissociation constant – The general ionization of an acid is as follows:
So the acid dissociation constant is as follows:
HA H+ + A-
Ka = [H+][A-]
[HA]There are many orders of magnitude spanned by Kavalues, so pKa is used instead:
pKa = log 1/Ka = - log10 Ka
The larger the value of the pKa, the smaller the extent of dissociation.
19Dr. Diala Abu-Hassan
![Page 20: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/20.jpg)
The equilibrium constant, Ka
Acid Conjugate base
Larger Ka means:More dissociation Smaller pKaStronger acid
20Dr. Diala Abu-Hassan
![Page 21: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/21.jpg)
21
Dec
reas
e ac
id s
tren
gth
In
crea
se a
cid
stre
ngth
Dr. Diala Abu-Hassan
![Page 22: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/22.jpg)
Acid dissociation constant
22Dr. Diala Abu-Hassan
![Page 23: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/23.jpg)
Base dissociation constant
[B]]][OH[BHKb
−+=
23
B + H2O BH+ + OH-
BH+ B + H+Reverse the reaction:
][BH][B][HKa +
+
=
Dr. Diala Abu-Hassan
![Page 24: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/24.jpg)
Weak Bases
24Dr. Diala Abu-Hassan
![Page 25: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/25.jpg)
Strong Acids - Dissociate readily- Ka is very large- Examples: Hydrochloric, Nitric; Sulfuric
Ex. HCl → H+ + Cl-
Ka = [H+] [Cl-][HCl]
[H+] = [acid]
Ex.1 M solution of HCl has a [H+] of
1 mM HCl solution has a [H+] of
1 M
0.1 M H2SO4 solution has a [H+] of
1 mM
0.2 M 25Dr. Diala Abu-Hassan
![Page 26: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/26.jpg)
Weak Acids - Dissociate slightly- Ka is smaller than strong acids- Examples: Acetic, Boric, Nitrous, Phosphoric, Sulfurous
Ex. CH3COOH + H2O CH3COO- + H3O+
Ka = [H+] [CH3COO-][CH3COOH]
What is the H+ of a 0.1 M solution of acetic acid? Ka= 1.74 X 10-5
1.74 X 10-5 = x2/[0.1 - x]
x2 = 1.74 X 10-6, or x = 1.32 X 10-3 M
26Dr. Diala Abu-Hassan
![Page 27: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/27.jpg)
27
HA + H2O H3O+ + A-
HA + H2O H3O+ + A-
CH3COOH + H2O CH3COO- + H3O+
Weak acid weak base strong base strong acid
CH3COOH + OH- CH3COO- + H2OStronger acid strong base weak base weak acid
Strong acid + strong base Weak base + Weak acid
Conjugate pair strength
Dr. Diala Abu-Hassan
![Page 28: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/28.jpg)
Equilibrium constant and the pH of water
H2O dissociates to a slight extent to form hydrogen (H+) and hydroxyl (OH-) ions.
H2O H+ + OH-
[H+] of pure water is only 0.0000001 M28Dr. Diala Abu-Hassan
![Page 29: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/29.jpg)
• Kw = [H+] [OH-] = 10-14
Example: A solution has an [OH-] = 10-9 M
[H3O+] = 10-5 M
Dissociation of water
![Page 30: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/30.jpg)
Example:
What is the [H+] of a 0.01 M NaOH solution?
Kw = [H+] x [OH-] = [H+] x 10-2 = 10-14
[H+] = 10-12 M
Example:
What is the [OH-] of a 0.01 M HCl solution?
Kw = [H+] x [OH-] = 10-2 x [OH-] = 10-14
[OH-] = 10-12 M
Problem solving
![Page 31: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/31.jpg)
31
Example:
Find the Ka of a 0.04 M weak acid HA whose [H+] is 1 x 10-4?
Ka = [A-] [H+] / [HA] = [H+]2 / [HA] = 10-4 x10-4 / 0.04 = 2.5 x 10-7
HA H+ + A-
Example 2:
What is the [H+] of a 0.05 M Ba(OH)2?
[OH-] = 2x 0.05 = 0.10 M = 1 x 10-1
[H+] = 1x 10-13
Ba(OH)2 Ba + 2OH-
Dr. Diala Abu-Hassan
![Page 32: Acids and Bases - JU Med: Class of 2019jumed2019.weebly.com/uploads/2/6/8/5/26855942/lecture_1...Chapter 10 softcopy will be sent Dr. Diala Abu -Hassan 2 Outline • Introduction-](https://reader031.fdocuments.in/reader031/viewer/2022030607/5ad65a1a7f8b9a6d708e0a1e/html5/thumbnails/32.jpg)
32
B + H2O BH+ + OH-
Example 4:
The [H+] of a 0.03 M weak base solution is 1 x 10-10 M. Calculate pKb?
[OH-] = 10-4
Kb = (10-4 x 10-4 ) / 0.03 = 3.33 x 10-7 M
pKb = -log Kb = 6.48
Dr. Diala Abu-Hassan