Organic AS Flashcards
What is the empirical formula
Empirical formula shows the simplest whole number ratio of elements within a molecule.
What is the molecular formula
Molecular formula shows the actual number of atoms of each element in a molecule
What does the structural formula show
Structural formula shows how the atoms are arranged in a molecule
What does the displayed formula show
Displayed formula shows a drawing of the arrangement of atoms in a molecule
ALL bonds must be shown
What does the skeletal formula show
Skeletal formula shows the carbon backbone and functional groups within molecules, no carbon-hydrogen bonds are shown
What are alkanes
Alkanes have single bonds between each carbon atom, all other available bonds are made to hydrogen atoms – they are called ‘saturated’ hydrocarbons
What are alkenes
Alkenes have a double bond between two of their carbon atoms – they are called ‘unsaturated’ hydrocarbons
What are alkly groups
Alkly groups are carbon chain groups bonded to another carbon chain
- CH3- methyl
- CH2CH3- ethyl
СН2СН2СН3-propyl
-СН2СН2СН2СН3-butyl
follows the same prefix as usual.
What does the functional group do
The functional group of a molecule dictates its chemistry, and its presence enables us to predict how the molecule is likely to react
What are structural isomers
Molecules that have the same molecular formula but different structures are called structural isomers.
What differs between chain isomers
They have different carbon chain arrangements to one another
What is Positional Isomerism
Where molecules that have the same molecular formula but have their functional group in different places
What are the steps to naming organic molecules
- When naming a compound, the length of the longest carbon chain must be determined. Use the prefix as for an alkane (meth, eth, prop…etc.).
- Alkyl and functional groups must be identified. Use the appropriate suffix (or prefix for halogenoalkanes) (-ol, -al, -oic acid, -yl for alkyl groups.).
- If a positional isomer is possible, the carbons in the chain must be numbered. The chain is always numbered, so a functional group or alkyl group is bonded to the lowest carbon number possible.
- When molecules contain two or more functional or alkyl groups, they are placed in alphabetical order.
- When numbering the other of priority is as so..
Halogens (lowest priority)
Alkyl groups
Alkenes
Other functional groups→ Highest priority
What is mean by a homologous series
“A series of chemically similar compounds which conform to a general molecular formula(same general formula)
Chemically similar or react in the same way .
• Each member of the series differs from the next by CH2
the members of the series show a graduation in physical properties.
• The length of the carbon chain has little effect on the chemical reactivity of the functional group
• The length of the carbon chain affects the physical properties (melting, boiling and solubility)
As the length of the carbon chain increases the melting point/boiling point increase because the intermolecular forces increase.
- Chain branching reduces melting points because the molecules pack together less well
What do isomers all have in common
Same molecular formula
What is a hydrocarbon
Something that contains carbon and hydrogen only
What is meant by the term saturated
Only single bonds present
What is meant by the term unsaturated
Contains double bonds (c=c)
Explain what happens in fractional distillation.
- crude oil is heated and enters the column as a vapour
- the vapour rises up the column, cooling as it does so
- crude oil is a mixture of alkanes with varying chain lengths and boiling points
- the different alkanes (fractions) condense at their boiling point and so will condense at different levels
- the fractions can then be pumped away separately
Why do we use cracking
Longer carbon chains are not very useful, therefore they are broken down to form smaller, more useful molecules. So we can make MORE PROFITS!
Explain the process of catalytic cracking
This method produces aromatic compounds with carbon rings. Lower temperatures around 720 K are used along with normal pressure, but a zeolite catalyst is needed to compensate for these less harsh conditions.
Explain the process of thermal cracking.
This method produces a high proportion of alkanes and alkenes. High temperatures around 1200 K and pressures around 7000 kPa are used to crack the carbon chains.
What is cracking .
Cracking is braking long chin alkanes into shorter alkanes and a alkene
Explain complete combustion of alkanes
When you burn (oxidise) alkanes (and other hydrocarbons)with plenty of oxygen you get only CO2 and H2O
Explain incomplete combustion
If there is not enough oxygen around when you burn a hydrocarbon you get incomplete combustion happening instead. This produces (soot) and carbon monoxide instead of, or as well as carbon dioxide.
What are alkanes primarily used as?
Fuels
Alkanes are found in fossil fuels and are used to generate energy in power stations, heating, and engines.
What are the products of complete combustion of alkanes?
Carbon dioxide and water
Complete combustion occurs when alkanes burn with plenty of oxygen.
What is the equation for the complete combustion of octane (C8H18)?
C8H18 + 25O2 → 8CO2 + 9H2O
This is an example of complete combustion.
What happens during incomplete combustion of hydrocarbons?
Produces carbon monoxide and particulate carbon
Incomplete combustion occurs when there is not enough oxygen.
What are the pollutants produced from incomplete combustion?
Carbon monoxide, particulate carbon, carbon dioxide, and water
Incomplete combustion can also produce unburnt hydrocarbons.
True or False: Carbon monoxide is non-toxic.
False
Carbon monoxide is poisonous and binds to hemoglobin, preventing oxygen transport in the body.
What is the role of catalytic converters in vehicles?
Remove pollutants from exhaust gases
Catalytic converters facilitate reactions that convert harmful pollutants into less harmful substances.
What are the three main pollutants from vehicle exhausts?
Nitrogen oxides, unburnt hydrocarbons, and carbon monoxide
These pollutants contribute to air quality issues and respiratory problems.
How does sulfur dioxide contribute to air pollution?
It forms sulfuric acid when dissolved in moisture, leading to acid rain
Acid rain can damage vegetation, buildings, and aquatic life.
What chemical reaction occurs when sulfur dioxide is removed from flue gases?
CaO + SO2 → CaSO3
This reaction produces calcium sulfite, a harmless salt.
What is the greenhouse effect?
Absorption and re-emission of infrared energy by greenhouse gases
This process keeps the Earth warm but contributes to global warming when CO2 levels rise.
What is global warming primarily caused by?
Increased carbon dioxide from burning fossil fuels
Most scientists agree that this process is leading to climate change.
Fill in the blank: The combustion of hydrocarbons containing sulfur leads to ______.
sulfur dioxide
What is produced when nitrogen oxides react with hydrocarbons in sunlight?
Ground-level ozone
Ground-level ozone is a major component of smog and can cause respiratory issues.
Describe one method for removing sulfur dioxide from flue gases.
Mixing with powdered calcium carbonate or calcium oxide
This creates an alkaline slurry that reacts with sulfur dioxide.
What is the general formula for nitrogen oxides?
NO
Nitrogen monoxide (NO) is produced under high pressure and temperature conditions in engines.
What are isomers?
Two molecules that have the same molecular formula but are arranged differently
What are structural isomers?
Isomers that have the same molecular formula but different structural formulas
List the three types of structural isomers.
- Chain isomers
- Position isomers
- Functional group isomers
What are chain isomers?
Isomers that have the same functional groups but different arrangements of the carbon skeleton
Provide an example of chain isomers for C4H10.
- Butane (straight-chain)
- Methylpropane (branched-chain)
What are position isomers?
Isomers that have the same skeleton and the same atoms or groups of atoms attached, but the attachments are at different carbon atoms
Give an example of position isomers for C4H9Cl.
- 1-chlorobutane (Cl attached to the first carbon)
- 2-chlorobutane (Cl attached to the second carbon)
What is the significance of numbering carbons when drawing isomers?
It makes it easier to see the longest chain and where side chains and atoms are attached
True or False: In displayed formulas, you must draw out all the bonds to get marks.
True
Fill in the blank: Chain isomers have the same functional groups but different arrangements of the _______.
carbon skeleton
What is a key tip when drawing isomers?
You don’t always have to draw all of the bonds; writing CH3 next to a bond is sufficient
What is the formula for butanoic acid?
C4H8O2
What is methylpropanoic acid an example of?
A branched-chain isomer of butanoic acid
What should you remember when a functional group can only go in one place on a molecule?
You don’t need to write the number
What is the relationship between structural isomers and molecular formula?
Structural isomers have the same molecular formula but different arrangements
What is nucleophilic substitution?
A reaction where a nucleophile replaces a leaving group in a molecule.
True or False: Nucleophilic substitution reactions can occur in both alkyl halides and aryl halides.
True
In nucleophilic substitution, what is the role of the nucleophile?
The nucleophile donates a pair of electrons to form a new bond with the substrate.
What is a leaving group in the context of nucleophilic substitution?
A group that is displaced from the substrate during the reaction.
Fill in the blank: In nucleophilic substitution reactions, the nucleophile is typically _____ charged or neutral.
negatively
What are the two main mechanisms of nucleophilic substitution?
SN1 and SN2 mechanisms.
Which mechanism involves a two-step process?
SN1 mechanism.
What is the rate-determining step in an SN2 reaction?
The single concerted step where the nucleophile attacks and the leaving group leaves.
True or False: The SN1 mechanism is unimolecular.
True
Which factor affects the rate of an SN2 reaction?
The concentration of both the nucleophile and the substrate.
What type of substrate favors an SN1 mechanism?
Tertiary substrates.
What type of substrate favors an SN2 mechanism?
Primary substrates.
In an SN1 reaction, what type of intermediate is formed?
A carbocation intermediate.
Fill in the blank: The strength of the nucleophile is often related to its _____ and _____ properties.
charge, polarizability
What effect does solvent have on nucleophilic substitution reactions?
It can stabilize or destabilize intermediates and transition states.
True or False: Polar protic solvents favor SN1 reactions.
True
Which type of solvent is preferred for SN2 reactions?
Polar aprotic solvents.
What is the stereochemical outcome of an SN2 reaction?
Inversion of configuration.
What is the stereochemical outcome of an SN1 reaction?
Racemic mixture if the substrate is chiral.
Fill in the blank: Good leaving groups are typically _____ and _____ stable.
weak bases, more
What role does sterics play in nucleophilic substitution?
Steric hindrance can prevent nucleophiles from attacking the substrate.
In which type of reaction would you expect to see a strong nucleophile?
SN2 reaction.
What is the relationship between nucleophilicity and basicity?
Nucleophilicity is a measure of a nucleophile’s ability to donate electrons, while basicity measures its ability to accept protons.
True or False: Nucleophiles can be neutral species.
True
What happens to the leaving group in a nucleophilic substitution reaction?
It is expelled from the substrate as a stable species.
What is the effect of a better nucleophile on the rate of an SN2 reaction?
It increases the reaction rate.
Fill in the blank: The _____ of the leaving group affects the rate of both SN1 and SN2 reactions.
stability
What is ozone depletion?
The reduction of the ozone layer in the Earth’s stratosphere.
True or False: Ozone is a molecule made up of three oxygen atoms.
True
What are the primary chemicals responsible for ozone depletion?
Chlorofluorocarbons (CFCs), halons, and other ozone-depleting substances (ODS).
Fill in the blank: The ozone layer is located in the _____ of the atmosphere.
stratosphere
What is the main function of the ozone layer?
To absorb the majority of the sun’s harmful ultraviolet (UV) radiation.
Which international treaty was established to phase out the production of ozone-depleting substances?
The Montreal Protocol.
True or False: Ozone depletion can lead to an increase in skin cancer rates.
True
What is the chemical formula for ozone?
O3
Multiple Choice: Which of the following is NOT an ozone-depleting substance? A) CFCs B) HFCs C) Halons
B) HFCs
What year did the Montreal Protocol come into effect?
1989
Fill in the blank: The ‘ozone hole’ is most commonly observed over _____ during the Southern Hemisphere’s spring.
Antarctica
True or False: Ozone depletion only occurs in polar regions.
False
What is the role of UV radiation in ozone depletion?
UV radiation breaks down ozone (O3) molecules, leading to depletion.
Multiple Choice: Which of the following is a consequence of ozone layer depletion? A) Increased plant growth B) Higher UV exposure C) Decreased global temperatures
B) Higher UV exposure
What is a potential environmental consequence of increased UV radiation due to ozone depletion?
Harm to marine ecosystems and phytoplankton.
Fill in the blank: Ozone depletion is primarily caused by human-made chemicals known as _____ .
chlorofluorocarbons (CFCs)
What is the significance of the year 2016 in relation to ozone depletion?
It was noted that the ozone layer is on track to recover due to the reduction of ozone-depleting substances.
True or False: Ozone is beneficial in the stratosphere but harmful at ground level.
True
What is the process by which ozone (O3) is formed in the stratosphere?
The photodissociation of oxygen molecules (O2) by UV light, followed by the recombination of free oxygen atoms with O2.
Multiple Choice: Which of the following is a natural source of ozone? A) Forest fires B) Industrial emissions C) Vehicle exhaust
A) Forest fires
What does the term ‘ozone-depleting potential’ (ODP) refer to?
The relative ability of a substance to destroy ozone compared to CFC-11.
Fill in the blank: The main human activities contributing to ozone depletion include the use of _____ in refrigeration and aerosol propellants.
CFCs
What is the impact of ozone depletion on human health?
Increased risk of skin cancer, cataracts, and weakened immune response.
True or False: The ozone layer has a uniform thickness around the globe.
False
What is the role of the stratospheric ozone layer in climate regulation?
It helps to regulate temperature by absorbing UV radiation, influencing weather patterns.
