YEAR 10 – Topic 10 – Oils, Alkanes, Alkenes and Alcohols Flashcards
What is a hydrocarbon?
A hydrocarbon is a molecule or a compound made from hydrogen and carbon ONLY.
What is an alkane?
An alkane is a saturated hydrocarbon compound, as it only has carbon - carbon single bonds. It can undergo substitution reactions. General formula: CnH2n+2
What is an alkene?
An alkene is an unsaturated hydrocarbon compound with a carbon - carbon double bond. They can undergo addition reactions and are a product of cracking. General formula: CnH2n
What is an alcohol?
Alcohols have a general formula of CnH2n+1OH. The functional group is OH. They can be oxidised to make carboxylic acids.
What is the general formula of an alkane?
CnH2n+2
What is the general formula of an alcohol?
C n H 2n+1 OH
What is the general formula of an alkene?
CnH2n
What is the order for the prefixes we use for alkanes and alkenes?
Meth- Eth- Prop- But- Pent- Hex- etc...
What is a functional group?
A functional group is an atom or a group of atoms that determines the main chemical properties of an organic compound. Eg. Alcohols = OH
What is an isomer?
An isomers are compounds with same molecular formula but a different displayed formula. (Can’t be flipped) this is easy to practice rather than flashcards… Ok
What is a molecular formula?
A chemical formula for a compound that gives the total number of atoms of every element in the molecule. Eg water = H2O
What is a structural formula?
A chemical formula for a compound which shows the arrangement of atoms in the molecule of the compound. Eg: CH3CH2CH3
What is the displayed formula?
The displayed formula is a structural formula that is drawn out. It shows how the atoms could be arranged in a 3D space.
What is an empirical formula?
A formula giving the proportions of elements present in a compound but not the actual numbers or arrangement of atoms. Eg: octane = C4H9
It is the simplest form of a compound
What is crude oil?
Crude oil is a fossil fuel and is made up of hundreds of different compounds, of which mainly hydrocarbons. It can be separated with fractional distillation.
What is fractional distillation?
Fractional distillation is a way of separating a mixture of liquids because of their different boiling points. An example is separating crude oil into it’s fractions.
Are the fractions pure substances or mixtures? Why?
They are a mixture as they boil over a range of temperatures (not like 100° exactly).
Properties of small hydrocarbons:
Small hydrocarbons:
- higher demand
- low boiling points (high up the fractioning column thingy)
- high flammability
- burns with a clean flame
- low viscosity (runny and easy to pour)
Properties of large hydrocarbons:
Properties of large hydrocarbons:
- lower demand
- high boiling points (lower in the fractioning column thingy)
- low flammability
- smoky flame
- light in colour
- high viscosity (thick and not easy to pour)
What is the order (from top to bottom) of the fuels produced in fractional distillation of crude oil?
Fuel gases (<40°c) Gasoline (petrol) (40-90°c) Naphtha (not sure what this is amz) (90-160°c) Kerosene (jet fuel) (160-250°c) Diesel (250-350°c) Residue/ Bitumen (>350°c)
What is a homologous series?
A homologous series is a series of compounds that:
- have the same functional group, so they have similar chemical properties
- show a trend (gradation) in physical properties
- can be described using the same general formula
- differ from the next by a -CH2- unit alkanes form the simplest of this series.
What is the difference between a saturated and an unsaturated hydrocarbon?
Saturated
– Only single C-C bonds
– Called alkanes
– General formula of CnH2n+2
Unsaturated
– Have double C=C bond/s (sometimes triple bonds)
– Called alkenes
– General formula of CnH2n
Short chain hydrocarbons have a _____ boiling point.
(Low/High)
What does this mean?
Low
They boil/ evaporate at lower temps.
Long chain hydrocarbons have a _____ boiling point.
(Low/High)
What does this mean?
High
They boil/ evaporate at higher temps.
Short chain hydrocarbons have a _____ viscosity.
(Low/High)
What does this mean?
Low
It means that they are more runny/pourable!!!
Long chain hydrocarbons have a _____ viscosity.
(Low/High)
What does this mean?
High
They are less runny/not pourable!!!
Short chain hydrocarbons have a _____ flammability.
(Low/High)
What does this mean?
High
They catch on fire more easily.
Long chain hydrocarbons have a _____ flammability.
(Low/High)
What does this mean?
Low
They don’t catch on fire easily.
Short chain hydrocarbons have a _____ volatility.
(Low/High)
What does this mean?
High
They turn into gases more easily.
Long chain hydrocarbons have a _____ volatility.
(Low/High)
What does this mean?
Low
They are harder to turn into gases.
Short chain hydrocarbons have a _____ colour.
Light/Colourless/Dark
Light/Colourless
Long chain hydrocarbons have a _____ colour.
Light/Colourless/Dark
Dark
What is cracking?
It is the process of making long-chain hydrocarbons into short-chain alkanes and and alkane.
What are the conditions necessary to carry out catalytic cracking?
600°C - 700°C
An alumina/silica/zeolite catalyst
What is crude oil?
It is a mixture of different hydrocarbons
How does fractional distillation work?
- Crude oil is heated and enters the fractioning column as a gas
- The fractioning column is cooler at the top and hotter at the bottom
- The fractions condense at their boiling point
- Long chains condense near the bottom and short chains near the top
- The fractions are separated according to boiling point
- This is done using fractional distillation
What are the main fractions obtained from crude oil?
start from the top of the column
Refinery gases Gasoline Kerosene Diesel Fuel oil Bitumen
What are Refinery Gases?
What are they used for?
Refinery gases are used in domestic heating and in cooking. They are found at the very top of the column.
What is Gasoline?
What is it used for?
Gasoline is used in fuels for cars (petrol) and is second from the top in the fractioning column.
What is Kerosene?
What is it used for?
Kerosene is used as a fuel for aircraft and is third from the top in the fractioning column.
What is Diesel?
What is it used for?
Diesel is a fuel used in some cars and larger vehicles like lorries and trains. It is found fourth from top in the fractioning column.
What is Fuel oil?
What is it used for?
Fuel oil is used as a fuel in large ships and in some power stations. It is fifth from the top of the fractioning column.
What is Bitumen?
What is it used for?
Bitumen is used to surface roads and roofs and is found at the very bottom of the fractioning column.
What is a fuel?
It is a substance that, when burned, releases heat energy.
What are the products of complete combustion of hydrocarbons with oxygen?
Carbon dioxide + water
What are the products of incomplete combustion of hydrocarbons with oxygen?
Carbon monoxide + water + carbon dioxide + soot/ash(C)
What is cracking?
Cracking is splitting up long chained hydrocarbons into smaller (in more demand) hydrocarbons. Cracking is a form of thermal decomposition. Cracking also produces alkenes.
What conditions are needed to crack long chained hydrocarbons?
600-700°c and a catalyst, eg. Alumina, silica or zeolite.
What is acid rain?
Acid rain is rain that is acidic, caused by sulfuric and nitric acids. It is bad as it can be damaging to wildlife.
What causes acid rain?(sulfur dioxide)
Sulfur dioxide can be found as an impurity in crude oil. When sulfur dioxide is mixed with water vapour in the air after being burnt, it forms dilute sulfuric acid. Clouds then rain acid rain.
What causes acid rain?(Nitrogen oxides)
Nitrogen oxides are created when the temperature is high enough for nitrogen and oxygen in the air to react, which happens often in car engines. NO or NO2 form. When they react with water vapour they make nitric acid, which then falls from the clouds as acid rain.
What is a substitution reaction?
A substitution reaction is where a halogen and an alkane react. They are called substitution reactions because atoms are swapped. They need UV (ultra violet) light to react.
What do substitution reactions need?(3 things)
- Alkane
- Halogen
- UV light
How does Bromine react with Methane?
Substitution reaction: UV
Methane(CH4) + Bromide(Br2) -> Bromomethane(BrCH3)+ Hydrogen bromide(HBr)
What is an addition reaction?
An addition reaction is where Halogens react with Alkenes, forming Haloalkanes. They are called addition reactions because the C=C double bond opens up and a halogen atom is added to each carbon.
What 2 things are needed for an addition reaction?
- Halogen
2. Alkene
How does Ethene react with Bromine?
Addition reaction:
Ethene(C2H4) + Bromide(Br2) -> dibromoethane (Br2C2H4)
How do you name alcohols?
-anol Meth Eth Prop But Pent Hex Etc...
How are carboxylic aids made?
They are made when an alcohol is oxidised. You need an oxidising agent, eg. Potassium dichromate(VI) in dilute sulfuric acid. It is also heated and changes colour from orange to green.
potassium dichromate(VI)/dilute sulfuric acid
Ethanol—————————————————————>ethanoic acid
Heat
What is microbial oxidation?
Some microorganisms can use alcohol as energy source. They use oxygen in the air to oxidise alcohol. The by-product is carboxylic acid.
What happens if alcohols are oxidised by being burnt?
They undergo complete combustion. The products are water and carbon dioxide.
What state are alcohols at room temperature?
Alcohols are liquid at room temp.
What is poly(Ethene)’s common name and use?
Polythene - bags and bottles
What s poly(propene)’s common name and use?
Polypropylene - crates and ropes
What’s poly(phenylethene)’s common name and use?
Polystyrene - packaging foam
What’s poly(chloroethene)’s common name and use?
PVC - window frames
What’s poly(tetrafluoroethene)’s common name and use?
PTFE/ Teflon - frying pans and plumbing tape
What’s poly(methyl 2 cyanopropenoate)’s common name and use?
Super glue - super glue
What poly(methyl 2 methylpropenoate)’s common name and use?
PMMA/ Perspex - Perspex (windows)
What is carboxylic acid’s functional group?
-COOH
Why are polymers hard to dispose?
Because they are unreactive, so microorganisms cant break them down. They have to be incinerated which is bad for the environment.
Why are addition polymers hard to dispose of?
Addition polymers are hard to dispose of because they have a C-C bond (saturated) which is very strong and not easily broken.
How do you make ethanol?
You make ethanol by:
- filling a conical flask with water and 1 teaspoon of yeast
- add 3 teaspoons of sugar
- put a big on and a delivery tube to a flask
- leave for a few days
- filter out dead yeast
- fractional distillation (78°c for ethanol)
