Chapter 9-13 Flashcards
acid
vinegar, citric acid (in juices), ascorbic acid (Vit. C)
smells sour, tastes sour
turns blue litmus paper red
can be neutralized by base
NaOH
NaOH (in liquid plumber), NH3 (in windex) tastes bitter or chalky, feels slippery, turns red litmus paper blue can be neutralized by acid
salt
table salt, baking soda-any ionic compound that is not a hydroxide or an oxide.
Arrhenius acids :
H-containing covalent compounds that produce H+ ions in water.
HCl(ag) H+(aq) + Cl- (aq
Arrhenius bases:
Hydroxide-containing ionic compounds that produce OH- ions in water.
NaOH (aq) Na+(aq) + OH-(aq)
acids
are H-containing covalent compounds that dissociate and release H+ in aqueous solutions.
Binary acids.
HF hydrofluoric acid
HCl hydrochloric acid
HBr hydrobromic acid
HI hydroiodic acid
Oxy acids
HNO3 nitric acid HNO2 nitrous acid
H2SO4 sulfuric acid H2SO3 sulfurous acid
HClO3 chloric acid HClO2 chlorous acid
H2CO3 carbonic acid
H3PO4 phosphoric acid H3PO3 phosphorous acid
water soluble hydroxides
NaOH sodium hydroxide
KOH potassium hydroxide
Ba(OH)2 barium hydroxide
Ca(OH)2 calcium hydroxide
Ca(OH)2 (aq) → Ca 2+ + 2OH-
water solubl metal oxides
Base anhydride
Na2O Sodium oxide
CaO calcium oxide
salt
A salt is an ionic compound that is not classified as bases.
Water-soluble salts (solubility rules) are always considered as 100% dissociated in water to produce ions. Therefore, soluble salts are strong electrolytes.
NaCl, NaHCO3, CaCO3, MgSO4, CuCl2
The Hydrogen Cation & The Proton
Recall hydrogen atom has 1 proton and 1 electron.
When a H atoms loses its electron,
H● → H+ + e-
H+ = the nucleus of hydrogen
= a proton
Therefore, another name for H+, is a proton.
Remember, H+ = proton
Bronsted-Lowry acid is
a proton (H+) donor;
Bronsted-Lowry base is
a proton (H+) acceptor.
Bronsted-Lowry Acid-Base Theory
thinking acid-base in terms of proton (H+) transfer
Any acid-base reaction involving a Bronsted-Lowry acid must also involve a Bonsted-Lowry base.
Proton donation cannot occur unless an acceptor is present.
H3O+ =
hydronium ion
= H+-H2O (the way H+ actually exist in aqueous solution)
= a hydrated hydrogen cation = a hydrated proton
Arrhenius vs. BrØnsted Acids & Bases
The Bronsted-Lowry theory is consistent with the Arrhenius definition.
Conjugate Acid-Base Pairs
In any acid-base reaction, there are two conjugate
acid-base pairs
Each pair related by the loss and gain of H+ .
One occurs in the forward direction.
One occurs in the reverse direction.
A Conjugate Acid-Base Pairs are related to each other by
gain or loss of H+.
To write the conjugate base of an acid (remove H+)
1) remove one H from the formula of acid
2) add a “-” charge to the remaining formula.
the conjugate base of HSO4- is SO42-
To write the conjugate acid of a base (add H+)
1) add one H to the formula of base
2) add a “+” charge to the formula.
the conjugate acid of HPO42- is H2PO4-
Acid-Base Neutralization Reactions
When acids and bases are mixed, they react with one another to produce water and a salt. This is called neutralization reactions
HX + MOH MX + HOH
acid + base → salt + water
(MX is the salt of acid HX)
Acid Base Neutralization reactions are
double replacement reactions.
Writing balanced equations for neutralization Reactions
HCl + NaOH → NaCl + HOH
(Na salt of HCl)
Acid + Base → Salt + HOH
** salt is an ionic compound; the total charges of cations and anions must be the same.
auto-ionization
A very small population of water molecules become ionized when 2 H2O molecules collide and H+ is transferred from one H2O molecule to another
- a reversible reaction that overwhelmingly favors the neutral H2O side
Out of every 1 billion water molecules, how many exists as H3O+ and OH-
only 2 actually exist as H3O+ and OH-
The Chemical Equation of
Water Auto-ionization
H2O + H2O H3O+ + OH−
Hydronium ion is a hydrated hydrogen cation.
For simplicity reason, we often write H3O+ as H+
H2O H+ + OH-
The Quantities of H3O+ and OH- in Pure Water
Notice equal number of H3O+ and OH- are formed during the ionization
- Pure Water is Neutral
Auto-ionization of water is a reversible reaction in which the molar concentrations of H3O+ and OH- are determined by a constant called
ion product constant, Kw
- Kw = [H3O+][OH-] = [1x 10-7][1x10-7] = 1 x 10-14
If [H3O+] goes ↑, [OH-] must goes ↓
If [H3O+] goes ↓, [OH-] must goes ↑
Adding Acid to H2O, makes
[H3O+] ↑, [OH-] ↓
Adding base to H2O makes
[OH-]↑, [H3O+.] ↓
pH
(power of Hydronium ion)
Notice the symbol is lower case p and capital H
The pH of a solution is the negative logarithm of the molar concentration of its hydronium ions.
pH = - log [H3O+]
Buffers are
solutions that can maintain its pH or resist major changes in pH when small amounts of acid or base are added to it.
Buffers are important in
the proper functioning of cells and blood.
Buffers in the body absorb
H3O+ or OH¯ from foods and cellular processes to maintain pH.
Buffer maintains the pH of our blood to
close to 7.4. A change in the pH of the blood affects the uptake of oxygen and cellular processes.
A buffer solution contains
equal moles of a weak (acid and its conjugate base (salt) or equal moles of weak base and its conjugate acid.
Any acid that is NOT in the strong acid table is a
weak acid
examples of buffer
1) a weak acid and its conjugate base (or salt of the acid):
H3PO4 + NaH2PO4(H2PO4-), H2CO3 + NaHCO3(HCO3-) 2) a weak base and its conjugate acid: NH3 + NH4Cl (NH4+)
acidosis
(CO2 pH ): emphysema, pneumonia, stroke, renal disease
alkalosis
(CO2 pH ): hyperventilation, vomiting, exercise, hypoxia
What is an Organic Compound?
Chemicals were classified as organic if they originated from living organisms rather than rocks.
The German scientist Wöhler synthesized the compound urea (a component of urine) without the use of any living organism, proving that it was possible to generate organic compounds independent of a living creature.
Organic chemistry is defined today as
the chemistry of the element carbon and its compounds.
Organic compounds contain
carbon and only a few other type of atoms (heteroatoms) H, O, N, the halogens (especially Cl, Br, and I) S and (to a lesser extent), P
Inorganic compounds are those
which are not based mainly on carbon.
- by convention, not all carbon-containing compounds are considered to be organic (for example: diamond, graphite, CO2, Na2CO3)
The simplest type of organic compounds are
hydrocarbons: compounds that are made of only H and C.
Saturated hydrocarbon
a hydrocarbon in which all carbon-carbon bonds are single bonds.
Unsaturated hydrocarbon is
a hydrocarbon that contains one or more carbon-carbon multiple bonds.
The simplest open-chain (acyclic) saturated hydrocarbons are called
alkanes
IUPAC Names And Condensed Structures For the First Ten Linear-Chain Alkanes
CH4 meth methane C2H6 eth ethane C3H8 prop propane C4H10 but butane C5H12 pent pentane C6H14 hex Hexane C7H16 hept heptane C8H18 oct octane C9H20 non nonae C10H22 dec decane
The general chemical formula of alkane:
CnH2n+2 C3H2(3) +2 = C3H8
Extended structural formula
shows all atoms and all bonds in a molecule.
Condensed structural formula
shows all bonds except C-H single bonds by writing the Hs to the right of C atom that is bonded to.
CH3-CH2-CH3
Skeletal Structure:
C-C-C
Alkanes with more than three carbon atoms can be arranged or joined in a multiple number of ways, forming different
isomers.
Structual isomers have the same
chemical formulas
Since atoms are hooked up differently structural isomers are
distinct molecules with distinct properties
Sturcture isomers are also called
constitutional isomers.
The Number of Structural Isomers With Increasing Number Of C
-increasing exponentially with # of C
C1: 1 isomer — methane C2: 1 isomer — ethane C3: 1 isomers — propane C4: 2 isomers — n-butane, isobutane C5: 3 isomers — n-pentane, isopentane, neopentane C6: 5 isomers C12: 355 isomers C32: 27,711,253,769 isomers C60: 22,158,734,535,770,411,074,184 (> 2.2 X 1022) isomers
Naming Branched Alkanes
Find the longest linear chain as the “parent chain”.
Treat the branch as a substitution of a hydrogen on the carbon at the branch point.
Alkyl Groups (R group)
An alkane that is missing one H from the terminal C.
Then binds to a carbon chain as a “substituent”
Named with a –yl ending.
- methyl CH3-
- ethyl
- propyl
- butyl
- pentyl
The Cycloalkanes
C atoms connecting to one another in a cyclic arrangement
The general chemical formula of cycloalkane:
CnH2n C5H2(5) = C5H10 cyclopentane
Physical Properties Of Alkanes and Cycloalkanes
Alkanes and cycloalkanes are nonpolar molecules and therefore insoluble in water
Less dense than water (d
Chemical Properties of Alkanes
Are typically not very reactive due to strong C-C single bonds
Fossil fuels are the major source of alkanes, existing on the earth for hundreds of millions of years.
combustion
by reacting with oxygen to produce carbon dioxide, water, and energy.
- alkane + O2 CO2 + H2O + energy
substitution
reaction by reacting with halgens which replace one of more H of the hydrocarbon
- CH3-CH3 + Cl2 CH3-CH2 –Cl + HCl
Combustion of Saturated Hydrocarbon
exothermic reaction:
650 kJ/mole per CH2 group
Substitution Reaction (Halogenation)
When we add a halogen (usually Br2 or Cl2) to an alkane, a halogen atom may substitute for a hydrogen atom.
Heat or light is essential for this reaction to work.
We will only consider monohalogenation in this class, where exactly one hydrogen atom is substituted. Halogenation occurs most readily on the most branched C atom in the alkane molecule.
In reality, more than one hydrogen atom may be substituted, giving many different products
The combustion reactions of alkane are
highly exothermic. Therefore, alkane are often used as fuels, such as methane (nature gas), propane, and butane (cigarette lighter), gasoline and diesel (for automobiles).
The most abundant source of alkanes is
fossil fuels, such as coal and petroleum/oil.
fractional distillation
boiling points of an alkane increases with its size. Therefore, hydrocarbons of different sizes can be separated by their boiling point
Oil Refinery: Fractional Distillation
Separating crude oil by the bp/size of alknaes.
The largest alkanes (highest bp) collect at the bottom.
The smallest alkanes (lowest bp) collect at the top.
Unsaturated hydrocarbons contain
at least one double and/or triple bond in their structure.
These groups are called unsaturated because
they can react with hydrogen under specific conditions to add more hydrogen to the molecule and to generate saturated hydrocarbons.
does saturated hydrocarbons react with hydrogen
no
3 major classes of unsaturated hydrocarbons
Alkenes contain a -C=C- double bond in their structure
Alkynes contain a –C=C- triple bond in their structure
Aromatic compounds contain a benzene ring in their structure
Naming for Alkenes & Alkynes
The parent hydrocarbon is the longest chain which contains the double or triple bond
For an alkene, change the suffix of the parent hydrocarbon from “-ane” to “-ene”
For an alkyne, change the suffix of the parent hydrocarbon from “-ane” to “-yne”
Number in the direction which gives the double or triple bond the lowest possible number. Use the lower of the 2 C that has unsaturation to indicate the position of the double/triple bond.
Cis-Trans Isomerism in Alkenes
The double bond in alkenes is rigid and cannot rotate.
The groups attaching to the carbons of the double bond are fixed relative to each other.
Cis-trans isomers occur when both C on the double bond are connect to different groups.
in the cis isomer the H
on the same side
in the trans-isomer the H
are on opposite side
Physical Properties of of Alkenes & Alkynes
insoluble in water, soluble in non-polar solvent,
lower density than water.
Alkenes with less than 4 carbon atoms are gases at room temperature,
Alkenes with 5 to 17 carbon atoms are liquids.
Chemical Properties of of Alkenes & Alkynes
More active than alkanes.
Reactions of Alkenes and Alkynes
Combustion reaction
Addition reaction
Polymerization reaction
Addition Reactions for Alkenes & Alkynes
a reaction in which atoms are added to double bond
hydrogenation
adding hydrogen atoms to the carbon atoms of double/triple bonds. (A metal catalyst, e.g., Ni, or Pt is required)
Hydrogenation of Oils
Vegetable oils are unsaturated fatty acids.
Adding H2 to double bonds in vegetable oils produces
Compounds with higher melting points.
Solids at room temperature such as margarine,
soft margarine, and shortening.
halogenation
adding halogen atoms add to the carbon atoms of a double bond or triple bond.
Bromine reacts with alkanes by
substitution, a reaction that requires light or heat.
Bromine reacts with
alkenea by addition, a reaction that occurs rapidly and does NOT require light or heat
Hydrohalogenation
adding the atoms of a hydrogen halide to the carbon atoms of a double bond or triple bond. (usually chloride or bromide)
Hydration
adding the atoms of a hydrogen halide to the carbon atoms of a double bond or triple bond. (usually chloride or bromide)
Aromatic Unsaturated Hydrocarbons
Benzene (C6H6):
A cyclic hexene with 3 conjugated double bonds that are hybridized among the 6 C atoms, turning all bonds inside the ring into 6 identical hybridized bonds. (Recall resonance structure from Chapter 4)
The identity of the 6 hybridized bonds is represented as a hexagon with a circle drawn inside.
Chemical Stability of The Benzene Ring
Benzene is chemically like saturated alkane, only substitution reactions occur in which the C-H bond is substituted by a C-X bond.
Aromatic compounds are named
With benzene as the parent chain.
Name R group or other atoms on the benzene ring as substitution.
Common Benzene Derivatives
Compounds “derived” from benzene
Toluene Aniline Phenol
(methylbenzene) (benzenamine) (Hydroxybenzene)
or aminobenzene
(check drawing)
Aromatic Compounds with 2 Groups
1, 3 1,4 1,2
Meta para ortho
m- p- o-
What Is a Functional Group?
a group of atoms that are bonded together in a unique binding pattern
The presence of a functional group in a compound gives the compound certain
characteristic chemical/physical properties
a functional group is
the part of a molecule where most of its chemical reactions occur.
example of a functional group
alkane — all single bonds, very stable
double bond: alkane → alkene
triple bond: alkane → alkyne
Functional Groups Containing
C-Heteroatom Single Bonds C-X
R = The hydrocarbon chain with attached X
Name of the Class Functional group(X)
Halogenated Hydrocarbons R-X, F, Cl, Br, I
Alcohols R-OH -OH
Ethers R-O-R -O-
Thiols R-SH -SH
Amines R-NH2 -NH2
Functional Groups Containing the C=O bond (The Carbonyl Group)
There are 5 major classes of carbonyl-containing organic compounds. They differ from one another by the atoms/groups attaching to the C atom.
- (check power point for structure ch12 pg4)
Most functional groups contain
highly electronegative atoms and, therefore, polar bonds.
Comp’ds with functional group have
higher polarity and stronger IMF.
R-X has higher
bp., mp. And water solubility than R-H of the same size.
R - X
R = Non-polar
Water insoluble X = Polar
Water soluble
Two opposing tendencies
When R is small (C
X dominant, polarity dominant
R-X is water soluble
When R is large (C > 4),
R dominant, non-polarity dominant
R-X is water insoluble
functional group IUPAC Prefix
Halgens alcohols amines thiols ether
- halo-
- hydroxyl -
- amino-
- thio-
- alkyoxy-
functional group suffix
alcohols
amines
thiols
- ol
- amine
- thiol
as halogenated hydrocarbon-use prefix
Halogen atoms are called
fluoro-, chloro-, bromo- or iodo-.
When double bond exist, the parent chain must include
the double bond and the chain is number from the end closest to the double bond, regardless of where X are located.
Naming Alcohols, R-OH
In IUPAC system replace –e of alkane name with -ol.
That are common names use the name of the alkyl group followed by alcohol.
Phenols
A phenol contains a hydroxyl group (—OH) attached to a benzene ring.
To name a phenol with two substituents
Assign C-1 to the carbon attached to the –OH.
Number the ring to give the lowest numbers.
Use prefixes o, m, and p for common names
Alcohols are classified by the number of
alkyl (R) groups attached to the OH (hydroxy) –bearing carbon into primary (1°), secondary (2°), or tertiary(3) alcohol.
Water Solubility of Alcohols
- “Like dissolves Like” and the IMF in water is hydrogen bonds.
- Compounds which are able to form hydrogen bonds are generally much more soluble in water than those which cannot
- Compounds able to form hydrogen bonds with water include alcohols, phenols, amines, and others
In general, compounds with (i) many carbon atoms and (ii) comparatively few oxygen and nitrogen atoms are
- not very soluble in water
alcohol with 1-4 carbon (up to butanol) is very soluble in water, but alcohols with 5 or more carbon are not.
Water Solubility of Phenol
Is soluble in water.
Has a hydroxyl group that ionizes slightly
Is weak acid, corrosive and irritating to the skin
Chemical Reactions of Alcohols
- Combustion is the reaction of an alcohol
with O2 to produce CO2 and H2O.2CH3OH + 3O2 → 2 CO2 + 4H2O + Heat - Dehydration
- Oxidation
Dehydration of alcohol
- check power oint ch 12 pg 22
Oxidation of Primary (1) Alcohols
When a primary alcohol is oxidized [O],
One H is removed from the –OH.
Another H is removed from the carbon bonded to the OH.
An aldehyde is produced.
Oxidation of Secondary (2) Alcohols
When a secondary alcohol is oxidized [O],
One H is removed from the –OH.
Another H is removed from the carbon bonded to the OH.
A ketone is produced.
Oxidation of Tertiary (3)Alcohols
Tertiary alcohols do not readily oxidize!
[O] Tertiary alcohol no reaction
Amines
R-NH2
Are derivatives of ammonia NH3.
Contain N attached to one or more alkyl or aromatic groups.
Naming Simple Amines
Amines are derivatives of NH3, with one or more alkly group attaching to N
Simple amines are named as alkylamines
The simplest aromatic amine, a benzene ring has an amino group is called
aniline
Amines are classified as
primary, secondary, or tertiary, based on the number of alkyl group attaching to the nitrogen atom (N).
Classification of Amines
In a primary (1°) amine, one carbon group is bonded to the nitrogen atom. A secondary (2°) amine has two carbon groups. A tertiary (3°) amine has three carbon groups
Amines in Our Body
Many hormones and neurotransmitters are amines.
These biologically active amines regulates important body activities, from immunity, blood pressure to sleep, emotions.
Properties of Amines
N in amine can form H-bonding with water. Amines with fewer than six carbon atoms are soluble in water.
Amines have strong, characteristic odors, and are toxic. The smells of ammonia, old fish, urine, rotting flesh, and semen are all mainly composed of amines
The most important chemical property of amines
Amines, like ammonia, are weak base!
Water Solubility of Amine Salts, RNH3+Cl-
Amine salts are ionic compounds.
They are solid at room temperature and but they are water soluble.
Many commonly used drugs are sold in the form of amine salts. A form that is not only stable/convenient but also easily absorbed by the body.
Alkaloids
Alkaloids are naturally-occurring amines, often with a complex molecular structure
Common examples include
morphine, codeine, heroin (painkiller)
caffeine, nicotine (stimulant), ephedrine
A heterocyclic organic compound
a cyclic compound in which one or more of the C atoms is the ring have been replaced with heteroatoms.
Cocaine is a heterocyclic amines
Extraction of Cocaine and Alkaloids
Cocaine and alkaloids are often isolated from natural sources (usually plants) by treating them with hydrochloric acid
The resulting amine salts formed are usually water-soluble, and readily dissolve in the acid solution.
Ethers, R-O-R
Ethers contain an ─O─ between two carbon groups.
Simple ether molecules are named by listing the alkyl names in alphabetical order followed by ether
Ethers as Anesthetics
Ethers Inhibit pain signals to the brain.
Ethyl ether CH3─CH2─O─CH2─CH3 were used for over a century, but caused nausea and were flammable.
Developed by 1960s were nonflammable
MTBE
Methyl tert-butyl ether
CH3
│
CH3─O─C─CH3
│
CH3
Is one of the most produced organic chemicals.
Is a fuel additive
Is used to improve gasoline combustion.
Use is questioned since the discovery that MTBE has contaminated water supplies.Thiols, R-SH
The –SH group is called sufhydryl group
Thiols often have strong odors.
Are used to detect gas leaks.
Are found in onions, oysters, and garlic.
Chemical Reaction Of Thiols
An important reaction for the 3D shape of proteins.
R-SH + HS-R2 –[O}–> R1-S-S-R2 + H2O Disulfide
The Carbonyl Group C=O
There are 5 major classes of carbonyl-containing organic compounds. They differ from one another by the atoms/groups attaching to the C atom of the carbonyl group.
- aldehyde RCHO
- Carboxylic acid RCOOH
- Amide RCONH2
- Ketone RCOR
- Ester RCOOR
The Carbonyl Group C=O
There are 5 major classes of carbonyl-containing organic compounds. They differ from one another by the atoms/groups attaching to the C atom of the carbonyl group.
- aldehyde RCHO
- Carboxylic acid RCOOH
- Amide RCONH2
- Ketone RCOR
- Ester RCOOR
Physical Properties OF C=O-containing Comp’ds: General
The CARBONYL group is polar, which causes dipole-dipole interactions between molecules.
A carboxylic acid has a hydroxyl group (OH) attaching to C of the C=O group giving additional H-bonds between carboxylic acid molecules.
Recall polarity↑, IMF↑, water solubility↑, b.p.↑
When R are small, RCHO, RCOR, RCOOH are water soluble,
water solubility ↓, when R ↑.
Orders of b.p./m.p.:
RCOOH > ROH > Aldehye/Ketone > Alkanes
Chemical Reactions of Ketones
Ketones can NOT be oxidized!
Ketones can undergo the following reactions:
1) Reduction
2) Addition Reaction: addition of alcohol to form hemiketal, followed by reaction of hemiketal with a 2nd alcohol to form ketal
Chemical Reactions of Ketones
Ketones can NOT be oxidized!
Ketones can undergo the following reactions:
1) Reduction
2) Addition Reaction: addition of alcohol to form hemiketal, followed by reaction of hemiketal with a 2nd alcohol to form ketal
Benedict’s Test For Aldehydes
Among the 5 classes of Carbonyl functional groups, only aldehydes can be oxidized by mild oxidizing agents, such as the Benedict’s Reagent.
Aldehyde, not ketone, turn the blue Benedict Reagent cloudy with brick red solid.
Oxidation of Ethanol in the Body
In the body,
Ethanol is oxidized by enzymes in the liver.
Aldehyde product impairs coordination
Addition Reactions of Aldehydes
Addition of an alcohol to a C=O double bond produces a hemiacetal, where the H atom of the alcohol adds to the O atom and R of the alcohol adds to the C atom.
Hemiacetals will react with an additional alcohol to form an acetal, where the new OR’ replaces the OH group of the hemiacetal.
Addition Reactions of Ketones
Ketones react with alcohols similarly as aldehydes, the products are hemiketals and ketals.
Carboxylic Acids, RCOOH
The –COOH functional group is called the carboxyl group.
IUPAC Name: Select the longest C chain as parent chain that includes the C of the carboxyl group. Name the parent chain by changing the –e ending of alkanes to –oic acid. The carboxyl C should be #1.
Reactions of Carboxylic Acids-2
RCOOH reacts with alcohol R’OH to produce an ester RCOOR’ and water, when a strong acid is added as a catalyst. This reaction is called esterification.
RCOOH reacts with amine RNH2 to produce an amide RCONHR and water. (This reaction underlies the formation of protein from amino acids)
Reactions of Carboxylic Acids-2
RCOOH reacts with alcohol R’OH to produce an ester RCOOR’ and water, when a strong acid is added as a catalyst. This reaction is called esterification.
RCOOH reacts with amine RNH2 to produce an amide RCONHR and water. (This reaction underlies the formation of protein from amino acids)
The name of an ester contains the names of
The alkyl group from the alcohol.
The carbon chain from the acid with –ate ending
