Chemistry Test 1- S4 Flashcards
What is crude oil a mixture of…
Hydrocarbon molecules
What is a hydrocarbon
A compound that contains only hydrogen and carbon atoms.
What is a way to separate crude oil into its separate fuels
Fractional distillation or distillation (boiling and condensing gases)
How does fractional distillation work
As the crude oil vapour enters the bottom of the tower and separates into its fractions (groups of molecules with similar boiling points). The higher boiling points separate at the bottom of the tower, where it is hottest and so on…. REVISE DIAGRAMM
What is a homologous series
Groups of compounds with similar chemical properties that fit a general formula
The first homologous series is the alkanes they are:
# have their carbon atoms arranged in a chain # Are saturated
What does
A= saturated
B= unsaturated mean
A= the carbon bonds are only single covalent bonds B= the carbon bonds are double covalent bonds
How do you name alkanes
Alkanes always end in -ane However the prefix is the variable: 1 carbon atom= methane 2 carbon atoms= ethane 3 carbon atoms= propane 4 carbon atoms= butane 5 carbon atoms= pentane 6 carbon atoms= hexane 7 carbon atoms= heptane 8 carbon atoms= octane
What is the molecular formula of a compound
It tells you the number of atoms of each element present in that molecule
E.g. CH4 means there are 4 hydrogen atoms and one carbon
What is a full structural formula
A drawing of the molecule when flattened out
H H H H
| | | |
H-C-C-C-C-H this is butane
| | | |
H H H HWhat is a shortened structural formula
When you take each bond one by one and write it out
CH3CH2CH2CH3
What is the general formula of alkanes
Cn H2n+2
What is an isomer
Compounds with the same molecular formula but different structural formula
How do isomers differ
They have the same number of carbon atoms in a chain but have different branch locations LOOK AT ISOMERS
What are the steps of the systematic naming of alkanes
- Find the longest chain of carbon atoms
- Number the longest carbon chain such that the branches are on the lowest number
- Indicate the position of each branch by the number of the carbon atom they are on
- Indicate the type of branch depending on the number of atoms in it (methyl, ethyl or propyl)
- Indicate the number of each type of branch
5.
Using these techniques name this
C
| -C-C-C-C-
2- methylbutane
The next homologous are the alkenes they:
# their carbon atoms are arranged in chains # they are unsaturated
How do you name alkenes
The same process as alkenes apart from the fact that they end in - ene
What is the General formula of the alkenes
CnH2n
How do you systematically name alkenes
- Find the longest chain of carbon atoms involving the c=c double bond and name it based off this
- Number the carbon atoms so that the double bond is on the lowest possible number
- Indicate the position of the double bond and add the position number to the formula
Using these techniques what is the name of this molecule:
| | |
-C-C=C-C-
| | | |
But-2-ene
The final homologous series are the cycloalkanes and they:
# their carbon atoms are arranged in rings # the molecules are saturated
How do you name cycloaklanes
Same process as alkanes apart from the fact that you put cyclo in front of the name
What is the general formula of the cycloalkanes
CnH2n
What is a combustion reaction
When a substance reacts (burns) with oxygen
What are the products of a hydrocarbon combustion reaction
Water
Carbon dioxide
Are unsaturated or saturated hydrocarbons more reactive
Unsaturated
What happens to bromine solution when it reacts with an saturated substance i.e. hex-1-ene
It decolourises the solution quickly
What happens to the bromine solution when reacted with an unsaturated substance i.e. hexane
It doesn’t decolourise the solution quickly
What is cracking and why is it important
Cracking is the breaking up of the less useful long chain molecules into the useful short chain molecules. It is important as it balances out the market demands for both molecules
What does cracking require
A high temperature or a catalyst ( which allows it to occur at a lower temperature, which is cheaper)
What are some of the products of cracking
Unsaturated, meaning they are more reactive
Suggest one way that you could crack C10H22
C8H18 + C2H4
What mixture is formed as a result of cracking
A mixture of alkanes and alkenes
What kind of molecule can undergo addition
Unsaturated
What happens during an addition reaction
The molecule being added seeks out the double bond in the unsaturated molecule and adds across it. E.g.
H H H H
| | | |
H-C=C-H + Br-Br ——> H-C-C-H
| |
H H
This means that the products substance is
Saturated
What is the addition of hydrogen called
Hydrogenation
What happens during hydrogenation
The same as addition except that instead of bromine or another substance being added it is hydrogen
What forms when an alkene undergoes hydrogenation
An alkane
What is the addition of water called
Hydration
What happens during hydration
The same as addition and hydrogenation except instead of hydrogen or other substances it is a water molecule being added
What is formed when an alkene undergoes hydration
An alkanol
What is required for hydration to occur
High temperature
High pressure
Catalyst
What is chemical energy
The energy stored within the bonds between atoms in a molecule
What is a fuel
A substance that burns to produce energy
REVISE CARBON CYCLE
Now
What pollutants are emitted from transport
Particulates such as soot Carbon monoxide Oxides or nitrogen Sulphur dioxide Hydrocarbons
How is carbon monoxide and particulates formed
When carbon based fuels burn inefficiently in a limited supply of oxygen
How is sulphur dioxide formed
When sulphur is burned this is the product gas
How are nitrogen oxides formed
When nitrogen and oxygen react together
Give an example of a greenhouse gas
Nitrous oxide
What are the products of natural gas and oxygen
Carbon dioxide
Water
What are most natural gases
Hydrocarbons
Why are alcohols good fuels
Release lots of energy
Burn easily with a clean flame
Renewable
How do your write combustion equations
The same as usual apart from the fact that you can use half molecules
What are all combustion reactions
Exothermic
What is the equation to figure out energy released from a fuel
Eh= cmdeltaT
What is the energy released measured in
Joules per kilogram per degree Celsius
Revise potential energy diagrams
Now
During an endothermic reaction the reactants have … potential energy than the products
Less
During an exothermic reaction the reactants have … potential energy than the products
More
What do you need to burn something
Fuel
Heat
Air
What is the activation energy of a reaction
The energy that must be provided so that reactant molecules can turn into products molecules
If a reaction has a low activation energy it will be …
Fast
What is an alcohol
A group of organic compounds with a hydroxyl (OH) group
What is an alkanol
A homologous series within the alcohols which derive from replacing a hydrogen atoms with a hydroxyl one
What is the general formula of the alkanol
CnH2n+1OH
How do you name alkanol
Same as all other apart from that you put a number in the middle to indicate which atom the hydroxyl group is attached too. (Number from lowest to highest)
What is the name of this alkanol
| | | -C3-C2-C1- | | |
Propan-1-ol
What is the trend of boiling points in the alkanol
As the alkanol size increases so too does the boiling point
Large alkanol are … with water
Small alkanol are … with water
Immiscible
Miscible
What is the formula to find out density
Density = mass/volume
What is the relationship between formula mass and density of alkanol
As dormira mass increases so too does average density.
What is fermentation
Using yeast to turn glucose into ethanol
What is gas is released from fermentation
Carbon dioxide
When addition occurs in alcohols what happens
The alkene is added with a H-OH molecule
What is dehydration
The reverse process of hydration in which an alcohol is decided into its deprecate alkene and H-OH molecule
What are the alkanoic acids
A homologous series which contains one or more carboxyl group
What is the carboxyl group
COOH
How do you form a formula equation for the alkanoic acids
Write out the normal equation but add the carboxyl group on the end
What is the general formula of the alkanoic acids
CnH2n+1COOH
What is the name of this alkanoic acid
| | | ||
C-C-C-C-C-OH
| | | | |
Pentanoic acid as it has five carbon atoms in a row as well as the hydroxyl group on the end
What are the properties of the alkanoic acids
Boiling points increase with size
Large molecules immiscible small molecules miscible
Low pH
What is the word equation of alkanoic acids reacting with metal
Alkanoic acid + metal = salt + hydrogen
How do you name the salt produced
Take the metal’s name and then add the type of acid on the end
E.g. ethanoic acid + sodium = sodium ethanoate
