Mod 7- HSC Organic Chemistry

alkane

single carbon-carbon bond, classified as a saturated molecule with the general formula CnH2n+2.

alkene

one or more carbon-carbon double bonds that are unsaturated and have the general formula CnH2n.

alkyne

one or more carbon-carbon triple bonds that are unsaturated and have the general formula CnH2n-2.

molecular formulae

indicates the number andtype of atoms of each element present in a molecule, but not how atoms are arranged

larger alkanes have ______ melting and boiling points, and _____ solubility when molecules become more non-polar

larger alkanes have higher melting and boiling points, and lower solubility when molecules become more non-polar

______ alkanes have higher boiling points because they have more surface area —> more __________ force

Linear alkanes have higher boiling points because they have more surface area —> more London dispersion forces.

why do alkenes have lower boiling and melting points than alkanes?

Alkenes have two less electrons than an alkane with the same number of carbonds so its dispersion force is slightly weaker

Why are alkynes very chemically reactive?

they have triple bonds and are more electron dense

why do alkynes have higher melting and boiling points than alkanes and alkenes?

their electrons are more easily polarised to create induced dipole-dipole forces

for alkenes and alkanes how are double and triple bonds specified?

with a number before or in between the number prefix and the “-ene” or “-yne” suffix

what is the similarity and difference between aldehydes and ketones?

similarity: carbonyl group (C=O)
Difference: carbonyl group is at terminal end in aldehydes and carbonyl group is bonded to adjacent C atoms in ketones

aldehyde suffix

-al

carboxylic acids (gorup and suffix)

contain a carboxyl group (-COOH) and are characterized by the suffix -oic acid

amines

nitrogen bonded to two or more carbon atoms and/or hydrogen atoms, characterized by the suffix -amine.

amides

carbonyl group bonded to a nitrogen atom that is bonded to hydrogen and alkyl group with suffix -amide

amide functional group

O=C - N - H2

what do the bracketed terms mean in ALKANE structural condensed formulas

alkyl group that is attached by a branch from the carbon that is to the left of the bracket

haloalkanes

alkanes that have one or more hydrogens that are relaced by halogens

hydroxyl group

-OH

what is an alcohol in terms of alkanes

an alkane with a hydroxyl group attached to a carbon in place of a hydrogen

Primary alcohol

carbon bonded to hydroxyl group is only bonded to one alkyl group

secondary alcohol

the carbon bonded to the hydroxyl group also bonded to two alkyl groups

amino functional group

One nitrogen atom bonded to two hydrogen atoms

primary amines arise when

one of three hydrogen atoms in ammonia is replaced by an alkyl

carbonyl functional group

C=O

carboxyl functional group

-COOH

amide functional group condensed structural formula

-CONH2

ester functional group

O=C-O-

two parts suffix for esters

_yl _oate

are alkanes polar or non-polar

non polar

what are the physical properties of hydrocarbons determined largely by

internmolecular forces and shape and size of the molecule

why do the properties of haloalkanes differ to hydrocarbons

they contain polar bonds

what kind of intermolecular forces do haloalkanes have

dipole-dipole forces

what is the property that melting points of hydrocarbons consider that boiling points of hydrocarbons don’t

number of carbons (even has higher melting points)

substitution reactions of ______

alkanes

addition reactions of _____

alkenes

hydrogenation reaction

alkenes + hydrogen gas in the presence of metal catalyst to form saturated alkane

what is the reaction of alkenes with halogens like

proceeds at room temperature and without a catalyst

hydrogen halides

chemical molecules that contain one hydrogen atom and one halogen atoms eg) HCl

what happens to the hydrogen halide when it reacts with alkenes

one hydrogen attaches itself to one of the carbons, and the halogen attaches itself to another carbon

what happens when an alkene is added to aqueous bromine

bromine solution goes from reddish brown to colourless (it has reacted)

reactions that involve water are called

hydration reactions

alkenes react with water to form

alcohols

what does the reaction of alkenes with water need

catalysts

how does the water molecule distribute itself when reacting with an alkene

H on one carbon and OH on another carbon

the boiling points of alcohols are _____ than those of their parent alkanes because

the boiling points of alcohols are higher than those of their parent alkanes because they have hydrogen bonds which are stronger than dispersion forces

branching reduces/increases the strength of dispersion forces

reduces

what is the trend of boiling points from primary to tertiary alcohols

decrease

why do shorter alcohol chains dissolve well in water

hydrogen bonds form between the partially positive hydrogen atom of the hydroxyl group and the lone-pair of electrons on the alcohol molecule

what is the general trend of solubility for alcohols in organic solvents

the larger the molecule, the more soluble

why do small alcohols like ethanol not dissolve well in nonpolar organic solvents

dispersion forces between their hydrocarbon chains and the solvent molecules are not strong enough to disrupt the hydrogen bonds that hold the alcohol molecules together

the reaction of a haloalkane with water or hydroxide ions produces?

alcohol

list three factors that fermentation depends on

starting material, purification process and temperature (strain of yeasts or bacteria, sealed or open to atmosphere)

monosaccharides general formula

Cn(H2O)n

temperature range for fermentation

15-35 degrees celsius

why do we not get 100% ethanol samples from fermentation?

yeast and bacteria cannot survive past 15% concentration of ethanol so fermentation stops at this concentration level

the presence of what functional group means ethanol has very different properties from ethene and chloroethene

hydroxyl functional group

setup to calculate the enthalpy of combustion of an alcohol

burning the alcohol below a container of water, and measuring the temperature change in the water and the amount of fuel used

give two examples of strong inorganic oxidising agents that can oxidise alcohols

potassium permanganate and potassium dichromate

what do primary alcohols oxidise into

aldehydes, then carboxylic acids

secondary alcohols oxidise into

ketones

how do tertiary alcohols oxidise with an inorganic oxidising agent

they are usually unreactive and do not oxidise

what is the molecular process of dehydration of an alcohol

the hydroxyl functional group is removed from one carbon and a hydrogen from another carbon is removed and bonds form to form water

what does the dehydration process of an alcohol form

alkene and H2O

for what type of alcohol does dehydration happen quickly and at room temperature

tertiary alcohol

what substances can be extracted from crude oil by fractional distillatiion

petrol, diesel, natural gas, bitumen, some lubricants

crude oil is a mixture of?

hydrocarbon molecules that are mostly members of alkanes

petrol is a mixture of hydrocarbons with the key component being _____

octane

what type of hydrocarbon does petro-diesel mostly contain

alkanes

what is natural gas mostly composed of

methane

three places that natural gas can be found

gas reservoirs, in petroleum deposits, coal deposits, in shale rock