Unit 4 Flashcards
Hydrocarbon?
Molecule with just carbons and hydrogens
Alkane?
Carbon and hydrogen only - saturated molecules
What intermolecular forces interact with alkanes?
Dispersion
What happens as the size of an alkane increases, in regards to its boiling point?
The larger the alkane, the increased strength and thus BP.
Larger =
- more atoms/surface area of interaction
- more electrons (which are dispersion forces)
- more dispersion
- INCREASE needed energy to break bonds
- Increase BP
What is dispersion forces?
Electrons orbit in each adjacent molecules, causing temporary dipoles
How do cyclic hydrocarbons similar to straight line carbon chains
similar chemical and physical properties
What can affect boiling point in alkanes?
Molar Mass (more electrons) thus heavier halogen has higher BP - (I > Br > Cl > F)
Branching
Size of ALKANE - length
How does branching in alkanes affect boiling point?
Molecules stack poorly against each other
Area of interaction smaller
LESS dispersion forces
LOWER (BP)
How does hydrogen bonding work and whats needed?
A H-FON bond within a molecule
- forming a partial charge (with partial negative on electronegative hydrogen FON)
- bonds with positive side on a hydrgeon on another atom
What does saturated mean in a hydrocarbon?
Saturated - single bonds, alkane, less reactive
Unsaturated - more than single bond (double, triple) - alkene, alkyne, more reactive
Which cyclocarbons are saturated vs unsaturated
Saturated - cycloalkane
Unsaturated - cycloalkene/alkyne
Whats Benzene?
C6H8
double bond every second carbon - but bond length/type in benzene are all the same
- electrons delocalise thus really stable
Hexagon with circle in middle (to represent delocalised electron cloud) located above and below the ring
Aromatic in QCAA?
Mean stuff like benzne
But also smelly stuff - esters
Saturated vs unsaturated as fuels
SATURATED
- single bonds only - stronger - more energy to break (thus release more energy which is what fuel is as) - thus alkanes and alchols
- unsaturated have double/triple bonds - weaker - can lead to different products and potential of incomplete combustion - CO/soot
Why are alkanes used as fuels
Because they release energy well and smaller ones vaporise well (VOLATILITY)
What does volatile mean?
The ability to change from liquid to gas (vaporise) - at lower boiling points or smaller alkanes
How does alkane size affect flammability?
Smaller alkanes are more volatile as they vaporise quicker - liquid to gas
Complete combustion?
burn alkane in excess oxygen to form CO2 (carbon dioxide) and water
- keep in mind co2 is greenhouse gas
Simple Substitution
Replacing one species on molecule with another
I.e.
C2H5Br +HCL –> C2H5Cl + HBr
Haloalkane + hydrogen halide –> Haloalkane + hydrogen halide
Simple Condensation
When small molecule is lost in formation of a larger molecule + water
I.e.
CH3COOH + CH3OH –> CH3COOCH3 + H2O
methanoic acid (acetic acid) + methanol –> methyl ethanoate (methyl acetate)
Carboxylic Acid + Alcohol –> Ester
Simple Reduction
Species gain electrons
- when electromagnetic atom - like oxygen is removed from a molecule
Simple Addition
Joining 2/more molecules to form a larger molecule
C2H4 +H2 –> C2H6
Alkene + hydrogen –> alkane
Simple Polymerisation
Joining many simple molecules to form a giant one
- reacting monomer molecules together in a chemical reaction to form polymer chain (polymers)
Simple Elimination
Removing small group of atoms from a larger molecule C2H5OH –> C2H4 + H2O
What mollecules can undergo addition?
Unsaturated molecules - double bond/triple broken to fit more atoms
Simple Oxidisation
Species loses electrons (electronegative atom like oxygen is added to a molecule)
Whats halogenation/type/condition if any?
Addition
Adding a halogen to generally a alkene forming a haloalkane
Alkene + Halogen –> dihaloalkane
ALKYNES
- same but form dihaloalkene –> tetrahaloalkane once do again
What are halogens and which are commonly used
F, Cl, Br, I
Only Cl and Br usually
F - doesnt undergo addition well
I - less reactive
Whats the way to memorise reductions vs oxidation and what it is
O xidation
I s
L ose
R eduction
I s
G ain
Haloalkane?
Alkane with 1/more hydrogens replaced by halogen
What type of reaction is alkene + halogen –> dihaloalkane?
addition - halogenation
Whats hydrogenation and type/condition if any/any extra info?
Addition
Adding hydrogen to alkene forming alkane
Alkene + Hydrogen –> (platinum) –> alkane
ALKYNE:
just turns alkyne –> alkene –> alkane
(platinum)
alkyne –> alkene (and stay) needs lindlar catalyst
Condition:
platinum catalyst
H2 GAS presence
Also known as reduction as its the gain of atoms aka GAIN OF ELECTRONS
- saturating any carbon-carbon double bond
Whats hydrohalogenation
Alkene + hydrogen halide
(addittion)
What condition is needed for hydrogenation?
H2 gas
metal catalyst (normally platinum)
What addition reactions require certain conditions and what are they?
Hydrogenation
(H2 gas and metal catalyst (normally platinum))
Hydration
(Steam for water, dilute aqueous acid as catalyst (H2SO4))
What is hydration/type/condition if any?
Addition
Adding water moleucle to alkene to form an alcohol
Alkene + steam (water) –> (dilute acid/h2so4) –> alcohol
Condition:
Steam for water
Dilute acid like H2SO4
Whats an alkyne
triple bond hydrocarbon C—C
What condition is required for the halogenation or substitution with chlorine?
UV light
Whats reduction in the context of addition
Hydrogenation or the gain of hydrogen atoms (electrons)
Since reduction is gain of electrons
(saturating any carbon-carbon double bond)
Whats the functional group/prefix or whatever of carboxylic acid?
R - C – Double bond O (carbonyl group)
C - OH (hydroxyl)
RCOOH
-anoic acid
Derivative of aldehyde since adding an oxygen to it (oxidation) to get OH group
Whats the functional group of ketone/prefix or whatever?
R-(C–O)-R
Carbonyl group in the middle of 2 R’s
-one
Whats the functional group/prefix or whatever of amide?
R-CONH2
R-CONH-R
R-CON-R-R
Carbon double bond O
Same carbon - N - 2H/ or /HR/ or /RR,
R-C–O
C-N-(H2/RH/R2) -depednidng on prim, sec, tertiary
-amide
i.e. butanamide
butan-2-amide
Whats the functional group/prefix or whatever of amine?
R-NH2
Functional: NH2
(can be NH1 with 2 R’s or just N with 3 R’s) changing to prim - sec - tertiary)
-amine
i.e. butylmine
butan-1-amine
Whats the functional group/prefix or whatever of alcohol?
Hydroxyl group (OH)
R-OH
-anol
i.e. butanol
butan-1-ol
Whats the functional group/prefix or whatever of aldehyde?
Like carboxylic acid (before) but with -H instead of -OH
R-CHO
R- C –O carbonyl group (O) Double bond
C - H
-anal
i.e. butanal
butan-1-al
Whats the functional group/prefix or whatever of nitrile?
R-C—N (triple bond to C—N) basicly a cyanide
cyanide functional group
alkane-nitrile
i.e. butanenitrile
butan-1-nitrile
Whats the functional group/prefix or whatever of alkyne?
C—C triple bond for hydrocarbon
yne
i.e. butyne
atWhats the functional group/prefix or whatever of alkene?
C–C double bond hydrocarbon
ene
i.e. butene
Whats the functional group/prefix or whatever of alkane?
C-C Single bond hydrocarbon
ane
i.e. butane
Whats the functional group/prefix or whatever of ester?
Whats the functional group/prefix or whatever of ether?
