CHEM 1405

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CHEM 1405

• Class Meeting 28

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Assignments and Reminders

• Homework problems due Thursday Apr 27th
• Chapter 12 even numbered problems 2-18
• Exam IV in test center Apr 27th through May 2nd
  
• Class website
  http//iws.ccccd.edu/jstankus/

Please use only one side of the page when
submitting Homework
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Acids General Properties

• Acids are substances that exhibit the following
  properties when dissolved in water.
• Acids taste sour. (Do Not Taste chemicals!)
• Acids produce a prickling or stinging sensation
  on the skin.
• Acids turn the color of the indicator dye litmus
  from blue to red.
• Acids react with many metals, such as magnesium,
  zinc, and iron, to produce ionic compounds and
  hydrogen gas.
• Acids react with bases, thereby losing their
  acidic properties.

4
Bases General Properties

• Bases exhibit the following properties when
  dissolved in water.
• Bases taste bitter. (Do not taste Chemicals)
• Bases feel slippery or soapy on the skin.
• Bases turn the color of the indicator dye litmus
  from red to blue.
• Bases react with acids, thereby losing their
  basic properties.

5
Arrhenius Theory

• In 1887 the Swedish chemist Svante Arrhenius
  proposed
• An acid is a molecular substance that ionizes
  (breaks up into ions) in aqueous solution into H
  ions and anions
• A base is a substance that produces OH- in
  aqueous solution

6
Limitations of Arrhenius Theory

• A free proton does not exist in water solutions
• Also limited to aqueous solutions

O
H
H
H
O
H
H
H
Hydrogen Ion (proton)
Water
Hydronium Ion
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Brønsted-Lowry Theory

• These shortcomings overcome by a theory proposed
  independently, in 1923, by J. N. Brønsted and T.
  M. Lowry

An acid is a proton donor A substance that
gives up H (a proton). A base is a proton
acceptor A substance that accepts H (a
proton).
8
Brønsted-Lowry Examples

• Hydrogen Chloride in water is Hydrochloric acid

9
Brønsted-Lowry Examples

• Ammonia in water is a base

10
Conjugate Pairs

• By Brønsted-Lowry theory, the products of an acid
  base reaction are also acids and bases

CH3COOH H2O H3O
CH3COO- Acid(1) Base(2)
Acid(2) Base(1)
An acid-base conjugate pair differs in structure
only by a proton (H) The conjugate acid of a
species is that species plus a proton The
conjugate base of a species is that species minus
a proton.
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Conjugate Pairs
A conjugate acid is formed when a Brønsted-Lowry
base accepts a proton. Every base has a conjugate
acid.
A conjugate base is formed when a Brønsted-Lowry
acid donates a proton. Every acid has a conjugate
base.
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Conjugate Pairs Examples

• Nitrous Acid

HNO2(aq) H2O H3O
NO2- Acid Base
Acid Base
Conjugate Acid Base Pairs
The conjugate base of HNO2 is NO2-, the species
that remains after HNO2 loses a proton.
13
Conjugate Pairs Examples

• Ammonia

NH3(aq) H2O OH-
NH4 Base Acid
Base Acid
Conjugate Acid Base Pairs
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Strong Acids

• Acids that are completely ionized in water
  solution are called strong acids.

H2O HCl(g) ? H(aq) Cl-(aq)
In 0.0010 M HCl(aq) H 0.0010 M Cl-
0.0010 M HCl 0
All the HCl is dissociated In solution
Square Brackets indicates concentration
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Weak Acids

• Acids that are only partially ionized in aqueous
  solution are called weak acids.

H2O HF(g) H(aq) F-(aq)
In 1 M HF(aq) less than 1 of the molecules ionize
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Monoprotic Acids

• One ionizable H atom per molecule
• Hydrochloric Acid HCl
• Hydrofluoric Acid HF
• Nitric Acid HNO3
• Hydrocyanic Acid HCN

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Polyprotic Acids

• Diprotic Acids
• Two ionizable H atom per molecule
• Sulfuric Acid H2SO4
• Carbonic Acid H2CO3
• Triprotic Acids
• Three ionizable H atoms per molucule
• Phosphoric Acid H3PO4

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Not all Hydrogens are Acidic

• No Hydrogens in methane (CH4) are given up in
  acidic solution
• Only one hydrogen in acetic acid (C2H4O2) is
  acidic

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How to tell the acidic hydrogens

• We write a molecular formula with ionizable H
  atoms first.
• HNO3 , H2SO4 , and H3PO4  
• HC2H3O2,

Ionizable Hydrogens
Non-Ionizable Hydrogens
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How to tell the acidic hydrogens

• In organic chemistry, we often use formulas that
  show the ionizable hydrogen atoms last.
• Example carboxylic acids.
• Acetic acid CH3COOH
• Formic acid HCOOH
• Propionic acid CH3CH2COOH
• Butyric acid CH3CH2CH2COOH
• In each of these, only the H atom on the O atom
  is ionizable.

Ionizable Hydrogens
Non-Ionizable Hydrogens
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Common Strong Acids

• Hydrochloric acid HCl(aq)
• Hydrobromic acid HBr(aq)
• Hydriodic acid HI(aq)
• Nitric acid HNO3(aq)
• Sulfuric acid H2SO4(aq)  
• Perchloric acid HClO4(aq)

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Common Bases

• Bases produce OH- ions in aqueous solution
  (Arrhenius definition)
• Group 1A and 2A Cations with Hydroxide ions
• NaOH Sodium Hydroxide
• (also known as Lye)
• KOH Potassium Hydroxide
• Ca(OH)2 Calcium Hydroxide
• (commonly called slaked lime)

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Strong Bases

• Strong bases are completely ionized

H2O NaOH(g) ? Na(aq)
OH-(aq)
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Strong Bases

• Alkali metal hydroxides
•  Lithium hydroxide LiOH(aq)
• Sodium hydroxide NaOH(aq)
• Potassium hydroxide KOH(aq)
• Rubidium hydroxide RbOH(aq)
• Cesium hydroxide CsOH(aq)
• Alkaline earth hydroxides
•  Calcium hydroxide Ca(OH)2(aq)
• Strontium hydroxide Sr(OH)2(aq)
• Barium hydroxide Ba(OH)2(aq)

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Weak Bases

• Bases that are only partially ionized in aqueous
  solution are called weak bases.

H2O NH3(g) H2O
NH4(aq) OH-(aq)
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Ammonia as a proton acceptor

• Lone pair can be used to accept proton

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Acidic Anhydrides

• Many acids are made by reaction of nonmetal
  oxides with water

SO3 H2O H2SO4
Nonmetal Oxide
Acid
An acidic anhydride is a substance that reacts
with water to produce an acid a nonmetal oxide
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Basic Anhydrides

• Many common bases can be made by reaction of
  metal oxides with water

CaO H2O Ca(OH)2
Metal Oxide
Base
A basic anhydride is a substance that reacts with
water to produce a basic solution a metal oxide
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Neutralization Reactions

• Recall from the description of acids and bases
• Acids react with bases, thereby losing their
  acidic properties
• Bases react with acids, thereby losing their
  basic properties
• An important reaction is the reaction of Acids
  with bases
• The reaction of acids and bases is called
  neutralization

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Neutralization Reaction

• Acids and bases react to cancel out or neutralize
  each other

HCl(aq) NaOH(aq) ? NaCl(aq) H2O
Acid
Base
Salt
Water
Complete Formula Equation
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Neutralization Reaction

• Ionic form of the equation shows what happens in
  the acid/base reaction

H(aq) Cl-(aq) Na(aq) OH-(aq) ? Na(aq)
Cl-(aq) H2O
Acid
Salt
Water
Base
Eliminate the Spectator Ions ions unchanged in
reaction
Net ionic reaction
H(aq) OH-(aq) ? H2O
Essence of neutralization reaction
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Example of Neutralization Reaction

• Write ionic and net ionic equation of aqueous HBr
  and Ba(OH)2

Make sure its balanced
HBr(aq) Ba(OH)2(aq) ? BaBr2 H2O
2
2
2 H(aq) 2 Br-(aq) Ba2(aq) 2 OH-(aq)
? Ba2(aq) 2 Br-(aq) 2 H2O
Eliminate Spectator Ions
2 H(aq) 2 OH-(aq) ? 2 H2O
Net Ionic equation
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Carbonic Acid

• Unstable and readily decomposes

H2CO3(aq) ? H2O CO2(g)
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Reactions of Acids with Carbonates and
Bicarbonates

• Sodium Bicarbonate
• Adding acid

Na HCO3- H Cl- ? H2CO3 Na
Cl-
H2CO3(aq) ? H2O CO2(g)
NaHCO3 HCl ? NaCl CO2 H2O
gas
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Acid Rain

• Normal rain pH 5.66.5
• Acid rain pH lt 5.6
• Caused by acidic anhydrides released from burning
  fossil fuels
• Involves both air and water pollution

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Acid Rain

• Burning of high sulfur coal
• S O2 ? SO2
• 2 SO2 O2 ? 2 SO3
• Recall that this is an acidic anhydride
• SO3 H2O ? H2SO4
• This sulfuric acid reacts with marble and
  limestone
• CaCO3 2 H ?Ca2 CO2 H2O

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Acid Rain Effects
What are the effects on the eco-system?
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Stomach Acids

• Stomach excretes HCl
• Aids digestion of food
• Hyperacidity too much HCl
• Caused by emotional stress or overindulgence
• Remove excess acid using a base
• Principle behind antacids
• Too much base may give alkalosis

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Antacids

• May contain one of the following bases
• NaHCO3
• Baking soda
• Safe and effective
• Not recommended for people with high blood
  pressure
• CaCO3
• Effective
• Should not be used for long periods of time

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• 3. Al(OH)3
• Similar behavior to CaCO3
• Mg(OH)2
• milk of magnesia
• Some brands of antacids are combinations of the
  above chemicals

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Acids, Bases, and Health

• Concentrated acids and bases are corrosive
  poisons
• May break down fabric or skin
• May release heat
• Strong acids break down proteins
• True for dilute solutions

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Acids and Bases in the Body

• Stomach acid
• Aids digestion
• Neutralized before entering rest of digestive
  system
• Blood
• Maintains narrow pH range
• Required for normal functioning of body

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Concentrations of Acids and Bases

• Dilution is a process of producing a more dilute
  solution from a more concentrated one, by the
  addition of an appropriate quantity of solvent

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Dilution

• Addition of solvent does not change the amount of
  solute in a solution but does change its
  concentration

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Dilution
Solve for moles of solute Moles of Solute
Molarity (M) x liters of solution (V) M x
V Since (Moles of solute)conc (Moles
of solute)dilute Mconc x
Vconc Mdil x Vdil
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Dilution example

• What volume of 1.000 M NaOH solution would you
  use to prepare 500 mL of 0.2500 M NaOH solution?

Mconc x Vconc Mdil x Vdil
Solve for Vconc
Substitute
Vconc 125 mL
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Acid-Base Titrations

• Titration is a laboratory procedure in which one
  reactant in solution is added quantitatively to
  another until the reaction is stoichiometrically
  complete.
• It is used to determine the concentration of a
  solution, such as an acid (reacted with a base).

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Procedures for a titration

• A measured volume of a solution of an acid of
  unknown concentration is transferred to a flask.
• Then, a solution of a base of known
  concentration is added carefully from a buret
  until the reaction of the acid with the base is
  just complete.
• The point at which the acid is just neutralized
  is called the equivalence point of the titration.
  
• At that point, the number of moles of OH- added
  equals the number of moles of H that were in the
  sample of acid

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Titration Example

• A flask contains 20.00 mL of HCl(aq) of unknown
  concentration. It is just neutralized by addition
  of 10.25 mL of 0.2010 M NaOH. What is the
  molarity of the acid?
• NaOH(aq)  HCl(aq) ? NaCl(aq)  H2O
• First calculate moles of NaOH
• Then use mole ratio from balanced equation to
  determine moles of HCl

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Titration Example Continued

• Calculate Molarity of HCl

Remember we need Volume in liters
51
Water Equilibria
Equilibrium lies far to left (most is H2O)

• Experimentally determined Concentrations
• H OH- 1.0 X 10-7 M

Remember Square brackets denote concentration
Ion Product of water (Kw) Kw HOH- (1.0
X 10-7) (1.0 X 10-7) 1.0 X 10-14
Relationship applies to all aqueous solutions
52
Ion Product of Water Example

• The concentration of H ions in a sample of lemon
  juice is 2.5 x 10-3 M. Calculate the
  concentration of OH- ions.

Kw HOH- 1.0 X 10-14
Solve for OH-
OH- 4.0 x 10-12 M
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pH scale

• Søren P.L. Sørenson proposed a simpler method to
  express acidity than Exponential Notation
• The pH scale is defined as
• The negative logarithm of H
• pH -logH

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pH Calculations

• pH means to represent the concentration of H in
  solution
• pH log H

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pH Example

• What is the pH of a solution that has
  H 1.0 x 10-4 M?
• pH -logH
• pH -log (1.0 x 10-4 )
• - (-4.00)
• pH 4.00

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pH Example

• What is the pH of a solution that has
  H 3.7 x 10-2 M?
• pH -logH
• pH -log (3.7 x 10-2 )
• - (-1.43)
• pH 1.43

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Significant Figures for Logarithms

• Find the number of significant figures in the
  number starting number
• Take the logarithm
• Report the number of places past the decimal
  equal to the number of sig figs

log (3.7 x 10-2 )
log (3.7) log(10-2)
0.57 -2 -1.43
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pH example

• What is the H in a solution with a pH 2.79?

pH -logH
Solve for H
logH -pH
antilog(logH) antilog(-pH)
H antilog(-pH)
Substitute
H antilog(-2.79) 0.0016 1.6 x 10-3 M
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pH Scale

• Typical values range from 0 to 14
• pH 7 neutral
• pH gt 7 basic
• pH lt 7 acidic

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pOH

• Similar to pH we can define pOH
• pOH -logOH-
• Relationship between pH and pOH

Remember Kw HOH- 1.0 X 10-14
pH pOH 14.00
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Equilibrium Calculations

• The ionization of a weak acid or base is a
  reversible reaction
• Typically reaches equilibrium when only a small
  percentage of molecules have ionized.

We will now treat these equilibria in a more
quantitative fashion
62
Equilibrium Constant Expressions
Coefficients
a A(g) b B(g)      c C(g) d D(g)
Products
Reactants
Equilibrium Constant
Remember C is molar concentration of C
63
Equilibrium Constant Example
64
Equilibrium Constant Example
65
Ionization of Weak Acids
At equilibrium
Ka
This is the Acid Ionization constant, Ka
66
Acid Ionization Constant Example

• Calculate the H in a 0.10 M solution of acetic
  acid

1.8 x 10-5
From table 10.1
From the balanced equation We know that H
CH3COO- x Therefore CH3COOH 0.10
M - x
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Acid Ionization Constant Example (cont)
1.8 x 10-5
Substituting into the equilibrium constant
expression
Since only a very small amount of acetic acid is
ionized 0.10-x 0.10
x2 1.8 x 10-6
Solving for x
H
x 1.3 x 10-3
Need to check assumptions
68
Acid Ionization Constant Example (cont)
Checking assumptions
We assumed that 0.10 x 0.10 with
that assumption we calculated x to be
0.0013 0.10 0.0013 0.10 to two significant
figures Our assumption is good
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Ionization of Weak Bases
At equilibrium
Since only a small amount of water reacts its
concentration is assumed constant
This is the base Ionization constant, Kb
70
Base Ionization Constant Example

• Calculate the OH- in a 0.010 M solution of
  aniline

4.2 x 10-10
From table 10.2
From the balanced equation We know that OH-
C6H5NH3 x Therefore C6H5NH3
0.010 M x 0.010 M
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Base Ionization Constant Example
Substituting into the base ionization expression
4.2 x 10-10
x2 4.2 x 10-12
x 2.0 x 10-6 M OH-
72
Buffers Control of pH

• A buffer solution is one in which the pH remains
  nearly constant even if acid or base is added.

73
Buffer solutions

• A buffer solution is a solution containing a weak
  acid and its salt, or a weak base and its salt.
• Small quantities of added acid are neutralized by
  one buffer component and small quantities of
  added base by the other.
• As a result, the solution pH is maintained nearly
  constant.

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How Buffers work

• Application of Le Chateliers Principle

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Common Buffer Solutions
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Common Ion Effect
Adding Acetate Ions Shifts equilibrium to left

• The common ion effect refers to the ability of
  ions from a strong electrolyte to repress the
  ionization of a weak acid or weak base or the
  solubility of a slightly soluble substance

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Common Ion Effect Example

• What is the H in a solution that is 0.10 M
  acetic acid and 0.10 M  sodium acetate?

Let x H Sodium acetate is totally
ionized CH3COO- 0.10 x CH3COOH
0.10 - x
Assume x ltlt 0.10
x H 1.8 x 10-5
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pH of Buffer Solutions
Manipulating the equilibrium expression
Where pKa -log(Ka)
This is the Henderson-Hasselbalch equation
79
Henderson-Hasselbalch Equation Example

• What is the pH of a solution that is 0.20 M H2S
  and 0.20 M HS-? 

The Ka 1 x 10-7 for H2S
80
Henderson-Hasselbalch Equation Example

• What is the pH of a solution that is 0.10 M HCN
  and 0.50 M NaCN? 

The Ka 6.2 x 10-10 for HCN
81
Buffer Capacity

• There are limits to how much acid or base a
  buffer can handle
• Generally related to the concentration of the
  buffer components
• Rule of thumb
• Effective pH range of a buffer is about
• pH pKa1

82
Buffers in Blood

• Blood Plasma normally varies from 7.35 to 7.45 in
  pH
• Blood pH gt 7.8 or lt 6.8 will do irreversible
  damage to the brain
• Blood pH lt 7.35 is acidosis
• Blood pH gt 7.45 is alkalosis
• Body has at least three buffer systems to
  maintain the proper pH

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Buffers in Blood
Bicarbonate/carbonic Acid system
Dihydrogen Phosphate/Monohydrogen Phosphate system
Protein system
84
Types of Radioactivity

• Rutherford found that radioactive elements gave
  off three types of radiation
• Alpha (a) particles
• Beta (b) particles
• Gamma (g) rays
• Two other types of radioactivity later found
• Positron (b )
• Electron Capture (E.C.)

Movie
85
Mass Number number of protons number of
Neutrons
Charge (if ion)
Mass Number
Symbol
Atomic Number
Atomic number of protons
86
Alpha (a) particles

• Just a Helium Nucleus (no electrons)
• Symbols a or
• Charge 2
• Mass of 4 amu
• Penetrating power slight

87
Beta (b) particles

• Electrons
• Symbols b, b- or
• Charge 1-
• Mass of 1/1837 amu
• Penetrating power intermediate

88
Gamma (g) rays

• Electromagnetic radiation
• Symbols g
• Charge 0
• Mass 0
• Penetrating power Great

89
Positron (b) particles

• Equal in mass but opposite in charge to electrons
• Symbols b or
• Charge 1
• Mass of 1/1837 amu
• Penetrating power limited
• Positrons in contact with electrons annilate each
  other generating g-rays

90
Electron Capture

• Nucleus absorbs inner shell electron which
  combines with a proton to form a neutron
• Symbols (E.C.)
• Accompanied by X-rays

91
Radioisotopes

• Radioactive decay
• Many isotopes are unstable
• Radioisotopes
• Nuclei that undergo radioactive decay
• May produce one or more types of radiation

92
Nuclear Equations

• Elements may change in nuclear reactions
• Total mass and sum of atomic numbers must be the
  same
• MUST specify isotope

Mass numbers 226 4
222
Atomic numbers 88
2 86
93
Alpha Decay

• Nucleus loses ? particle
• Mass decreases by 4 and atomic number decreases
  by 2

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Beta Decay

• Nucleus loses ? particle
• No change in mass but atomic number increases

95
Positron Emission ?

• Loses a positron
• Equal mass but opposite charge of an electron
• Decrease in atomic number and no change in mass

n
96
Electron Capture

• Nucleus absorbs an electron and then releases an
  X-ray
• Mass number stays the same and atomic number
  decreases

n
97
Nuclear Reaction Examples

• Write a balanced nuclear equation for
  Plutonium-239 emitting an alpha particle when it
  decays
• First find the proper symbol for the
  Plutonium-239 isotope
• Then the proper symbol for an alpha particle
• Write the equation
• Remember that the mass numbers and the atomic
  numbers must add up
• Find the symbol for the atomic number calculated

98
Nuclear Reaction Examples

• Write a balanced nuclear equation for
  Protactinium-234 undergoing beta decay
• First find the proper symbol for the
  Protactinium-234 isotope
• Then the proper symbol for an beta particle
• Write the equation
• Remember that the mass numbers and the atomic
  numbers must add up
• Find the symbol for the atomic number calculated

99
Nuclear Reaction Examples

• Write a balanced nuclear equation for Carbon-10
  emitting a positron as it decays
• First find the proper symbol for the Carbon-10
  isotope
• Then the proper symbol for an positron
• Write the equation
• Remember that the mass numbers and the atomic
  numbers must add up
• Find the symbol for the atomic number calculated

100
Differences Between Chemical and Nuclear Reactions
101
Penetrating Power of Radiation

• The more mass the particle has, the less
  penetrating it is
• The faster the particle is, the more penetrating
  it is

102
Ionizing Radiation

• Ionizing radiation is radiation that causes the
  formation of ions from neutral particles.
• Alpha Particles
• Beta Particles
• Gamma Rays
• X-rays

103
Ionizing Radiation

• In the body, ionizing radiation most often
  interacts with water molecules.
• The reactive particles formed from water attack
  other molecules essential to proper cell
  function, thus damaging living tissue.

104
Radiation Shielding
105
Dangers of Radioactive substances
106
Radiation Protection

• Distance  The more distant the source, the
  greater the safety.
• Sample size  The smaller the radiating sample,
  the greater the safety.
• Type of radiation  The less penetrating the
  radiation, the greater the safety. Thus, for
  external sources safety increases in the order g,
  b, a.

107
Radiation Protection

• Half-life  The longer the half-life, the greater
  the safety.
• Time  Generally, the shorter the time of
  exposure, the greater the safety
• Frequency  The fewer the exposures, the greater
  the safety.

108
Radiation Measurement

• Rate of nuclear disintegrations
• curies (Ci)
• 1 curie is 3.7 x 1010 disintegrations per second

109
Radiation Measurement

• Effect of Radiation on matter
• Unit roentgen (R)
• Measure of the ability of a X-ray or gamma ray
  source to ionize air
• Unit rad (radiation absorbed dose)
• Amount of energy absorbed by matter
• 1 rad is amount of radiation that cause 1 kg of a
  substance to absorb 0.01 J of energy

110
Half-Life

• Period for one-half of the original elements to
  undergo radioactive decay
• Characteristic for each isotope
• Fraction remaining
• n number of half-lives

111
Half Life Example

• You obtain a new sample of Cobalt-60 with a
  half-life of 5.25 years, with a mass of 400 mg.
  How much cobat-50 remains after 15.75 years
  (three half-lives)?

Where n number of half lifes (here n3)
The amount of Cobalt-60 remaing is
112
Half Life Example

• You obtain a 20.0 mg sample of mercury-190 with a
  half-life of 20 minutes. How much of the
  mercury-190 remains after 2 hr?

Where n number of half lifes (here n6)
The amount of mercury190 remaining is
113
Radioisotopic Dating

• Use certain isotopes to estimate the age of
  various items
• 235U half-life 4.5 billion years
• Determine age of rock
• 3H half-life 12.3 years
• Used to date aged wines

114
Carbon-14 Dating

• 99.9 12C
• Produce 14C in upper atmosphere
• Half-life of 5730 years
• 50,000 y maximum age for dating

115
Isotopes Useful in Radioactive Dating
116
Carbon-14 dating example

• A piece of fossilized wood has a carbon-14
  activity that is one-sixteenth (1/16) that of new
  wood. How old is the artifact? (The
  half-life of carbon-14 is 5730 years.)
• solving for n we find that n4
  half-lives
• Therefore the artifact is 22,920 years old
  

117
Artificial Transmutation

• Transmutation changes one element into another
• Middle Ages change lead to gold
• In 1919 Rutherford established protons as
  fundamental particles
• Basic building blocks of nuclei

118
Artificial Transmutation Example

• Write a balanced equation for the nuclear
  reaction in which potassium-39 is bombarded with
  neutrons, producing chlorine-36.
• Mass numbers 39 1 36 ?
• Atomic numbers 19 0 17 ?

119
Nuclear Fission Splitting the Atom

• Break a large nucleus into smaller nuclei

120
Nuclear Chain Reaction

• Neutrons from one fission event split further
  atoms
• Only certain isotopes, fissile isotopes, undergo
  nuclear chain reactions

121
Manhattan Project

• How to sustain the nuclear reaction?
• How to enrich uranium to gt90 235U?
• Only 0.7 natural abundance
• How to make 239Pu (another fissile isotope)?
• How to make a nuclear fission bomb?

122
Radioactive Fallout

• Nuclear bomb detonated radioactive materials may
  rain down miles away and days later
• Some may be unreacted U or Pu
• Radioactive isotopes produced during the explosion

123
Nuclear Power Plants

• Provide 20 U.S. electricity
• France gt70
• Slow controlled release of energy
• Need 2.53.5 235U
• Problem with disposal of radioactive waste

124
Nuclear Fusion

• Reaction takes smaller nuclei and builds larger
  ones
• Also called thermonuclear reactions

• Releases tremendous amounts of energy
• 1 g of H would release same as 20 tons of coal

125
Uses of Radioisotopes

• Tracers
• Easy to detect
• Different isotopes have similar chemical and
  physical properties
• Physical, chemical, or biological processes

• Agriculture
• Induce heritable genetic alterations mutations
• Preservative
• Destroys microorganisms with little change to
  taste or appearance of the food

126
Nuclear Medicine

• Used for two purposes
• Therapeutic treat or cure disease using
  radiation
• Diagnostic obtain information about patients
  health

127
Radiation Therapy

• Radiation most lethal to dividing cells
• Makes some forms of cancer susceptible
• Try to destroy cancer cells before too much
  damage to healthy cells
• Direct radiation at cancer cells
• Gives rise to side effects

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Diagnostic Uses

• Many different isotopes used
• Can measure specific things
• Iodine-131 to locate tumors in thyroid
• Selenium-75 to look at pancreas
• Gadolinium-153 to determine bone mineralization

129
Nuclear Medicine Isotopes
Table 12.4 in book
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Computed Tomography (CT scans)

• Uses X-rays to assemble a 3D image
• Also known as CAT scan (Computed Axial Tomography)

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PET Imaging

• Positron emission tomography (PET)
• Uses an isotope that emits a positron
• Observe amount of radiation released
• Observe g radiation

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Techniques can be Combined

• PET scan and CT scan

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Other Imaging Techniquesnon-ionizing radiation

• MRI Magnetic Resonance Imaging
• Measures magnetic properties of a nucleus
• (originally known as Nuclear Magnetic Resonance
  NMR)
• Can give chemical information
• Ultra-Sound
• Uses reflection of soundwaves to develop an image