Chapter 14 Flashcards
Name and draw the structures of methane, ethane, ethene, ethanol, ethanoic acid and the products of the reactions
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State the type of compound present, given a chemical name ending in -ane, -ene, -ol, or -oic acid or a molecular structure
Alkane: This is the most basic organic compound and usually consists of only C–C bonds and C–H bonds.
Alkene: This indicates that there is a C=C (carbon to carbon) double bond present.
Alcohol: This indicates that there is an O–H group present.
Carboxylic acid: This shows there is a carbon which has a C=O double bond with oxygen, and a single bond to an OH group.
meth- contains one carbon atom eth- contains two carbon atoms prop- contains three carbon atoms but- contains four carbon atoms pent- contains five carbon atoms.
Name and draw the structures of the unbranched alkanes, alkenes (not cis-trans), alcohols and acids containing up to four carbon atoms per molecule
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Name and draw the structural formulae of the esters which can be made from unbranched alcohols and carboxylic acids, each containing up to four carbon atoms
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Name the fuels
coal, natural gas and petroleum
What is the main constituent of
natural gas?
methane
Describe petroleum
a mixture of hydrocarbons and its separation into useful fractions by fractional distillation
Describe the properties of molecules within a fraction
The less carbon atoms, the lower the boiling point.
As the number of carbon atoms in the hydrocarbon increases:
- the boiling point increases
- the viscosity increases
- the volatility decreases.
Name the uses of the fractions
Refinery gas: used as bottled gas for heating and cooking.
Gasoline: used as a fuel for cars.
Naphtha: used as a base for manufacturing many other chemicals, for example, solvents used by painter decorators.
Kerosene: used for jet fuel
Diesel oil: used as a fuel for trucks in diesel engines.
Fuel oil: used as a fuel for ships or heating homes.
Lubricating oil: used for lubricating machinery, and as a base for polishes and waxes.
Bitumen: used for laying tarmac on roads.
Describe the concept of homologous series
a ‘family’ of similar compounds with similar chemical properties due to the presence of the same functional group
Describe the general characteristics of a homologous series
They have the same structural formula; all come from the same functional group; similar chemical properties.
the alkanes as a homologous series are generally unreactive except for combustion reactions.
The alkenes that have a C=C bond are similar to alkanes except that they are more reactive due to the double bond that can break and open up to join with other atoms.
The alcohols that contain the –OH functional group display the property of miscibility in water, whereas alkanes without the –OH group are not miscible in water. Carboxylic acids with the –COOH readily undergo further chemical reactions and so, for example, can react with alcohols to form esters as we discovered in previous subtopics. The share the similar chemical properties and the same functional groups
Describe and identify structural isomerism
when compounds have similar molecular formulas but different arrangement of atoms
Describe the properties of alkanes
generally unreactive, except in terms of burning
Describe the bonding in alkanes
Alkanes are generally unreactive due to the strength of their covalent bonds. They are often referred to as saturated hydrocarbons. This means that the molecule only has single covalent bonds. They contain only C-C bonds and C-H bonds and each carbon forms 4 covalent bonds.
Describe substitution reactions of alkanes with chlorine
In a substitution reaction, an alkane reacts with a halogen to produce a halogenoalkane. This reaction is photochemical, only reacting in the presence of sunlight.
Chlorine molecules (Cl 2 ) are split up and then go on to react with methane in a chain reaction, which produces several different compounds. The product of this reaction can be chloromethane, dichloromethane, trichloromethane or Tetrachloromethane and hydrochloric acid (HCl) or hydrogen halide.
Describe the manufacture of alkenes and of hydrogen by cracking
Cracking is the breaking of long alkane chains (and other more complex organic molecules) into simpler smaller ones through the use of high heat, pressure and catalysts. This process involved heating the hydrocarbons to vaporise them. The vapours are then either passed over a hot catalyst (silica or alumina) or mixed with steam and heated to a very high temperature (temperature in the range of 600-700 ̊C) so that thermal decomposition reactions can occur. The products of cracking include shorter chain alkanes and alkenes (or hydrogen)
Distinguish between saturated and unsaturated hydrocarbons from molecular structures and by reaction with aqueous bromine
Unsaturated = contain one or more C=C double bonds e.g. alkenes while saturated = contain no C=C double bonds e.g. alkanes. Unsaturated hydrocarbons react with bromine in an addition reaction, decolourising it as there is no more bromine (orange to colourless) and saturated hydrocarbons do not react with bromine and therefore the solution will remain orange
Describe the formation of poly(ethene)
an example of addition polymerisation of monomer units
Describe the properties of alkenes in terms of addition reactions with bromine, hydrogen and steam
Addition reactions involve the removal of C=C double bond as the C=C bond is very reactive and can easily react to form C-C.
- alkene + bromine → dibromoalkane. E.g. Ethene + bromine → 1,2-dibromoethane as the double bond breaks.
- alkene + steam → alcohol, E.g. Ethene + steam → ethanol this reaction is called hydrogenation
- alkene + hydrogen → alkane, E.g. Ethene + hydrogen → ethane
Describe the manufacture of ethanol by fermentation and by the catalytic addition of steam to ethene
ethene gas obtained from cracking can be further reacted with water in the form of steam to produce ethanol in a process also known as hydration. This reaction is carried out at a temperature of about 550 °C and in the presence of a strong acid, such as sulfuric or phosphoric acid, which acts as a catalyst. Also, fermentation causes ethanol to be produced as yeast respires anaerobically taking glucose to produce ethanol and carbon dioxide.
Describe the properties of ethanol in terms of burning
Ethanol is highly flammable and can easily be ignited at temperatures lower than room temperature. It burns readily with oxygen with a clean blue flame and does not produce any soot, releasing a lot of heat energy
Name the uses of ethanol
It is used as a solvent for substances that can not dissolve in water and is a solvent for perfume and makeup. Ethanol can also be used as a biofuel for cars.
Outline the advantages and disadvantages of the two methods of manufacturing ethanol
Fermentation advantages: ▪ Renewable raw materials ▪ Warm, normal pressure (inexpensive) ▪ Little energy needed Fermentation disadvantages: ▪ A lot of workers needed ▪ Slow ▪ Impure – needs treatment
Steam advantages: ▪ Continuous process (runs all the time) ▪ Few workers needed ▪ Fast ▪ Pure Steam disadvantages: ▪ Non-renewable raw materials ▪ High temperature and pressure (expensive) ▪ A lot of energy needed
Describe the properties of aqueous ethanoic acid
It dissolves in water to produce an acidic solution, has a melting point of 17˚C and a boiling point of approximately 118 °C. It forms ice-like crystals just below 17 °C and in its pure form, is corrosive.
Describe the formation of ethanoic acid by the oxidation of ethanol by fermentation and with acidified potassium manganate(VII)
When ethanoic acid is produced from alcohol as a continuation of the fermentation process, the process happens in the presence of the bacteria acetobacter, which acts as a catalyst. This is acid fermentation. potassium manganate(VIII) is a strong oxidising agent and is used in the presence of sulfuric acid and heat to produce ethanoic acid.
Describe ethanoic acid
a typical weak acid, which only partially ionises.
Describe the reaction of a carboxylic acid with an alcohol in the presence of a catalyst to give an ester
Esters are produced in the reaction between a carboxylic acid and an alcohol in the presence of a catalyst. E.g ethanoic acid and ethanol with concentrated sulfuric acid as a catalyst. This is called esterification.
- the C–O bond of the OH hydroxyl group in ethanoic acid breaks
- the O–H bond in ethanol breaks
- the two remaining parts from each molecule join together forming a C–O bond for the ester
- a condensation reaction between OH and H occur to produce water.
Name: first part of the alcohol +yl, second part from the acid +oate.
polymers
large molecules built up from small units (monomers)
Name some typical uses of plastics and of man-made fibres such as nylon and Terylene
Plastics:
o Plastic bags
o Clingfilm
o Buckets, other plastic tools
Man-made fibres such as nylon and Terylene:
o Drawn into very fine fibres and woven into cloth for clothing
o Other natural fibres (e.g. cotton) can be mixed with nylon or polyester
o fibres to make a soft but hard-wearing cloth
Deduce the structure of the polymer product from a given alkene and vice versa
the polymer product would be a long chain of the alkene without the C=C and instead with –C …. C- at the end, i.e. open branches
Describe the formation of nylon (a polyamide) and Terylene (a polyester) by condensation polymerisation
In a polyamide reaction for nylon, a carbon bond from the dichloride monomer joins with a nitrogen bond from the diamine monomer to produce a polyamide (nylon) and hydrochloric acid, which is given off, or condensed, from the original monomer units. The reaction will continue with carbon and nitrogen atoms forming bonds with each other alternately. The place where the two functional groups join together is known as the amide linkage.
For terylene, we can see a carbon from the acid join with the oxygen from the diol, ejecting a water molecule in the process. This linkage between the monomer units is a O–C=O bond, known as an ester linkage, and gives this polymer the name polyester. The reaction will continue with carbon atoms bonding to oxygen atoms alternately to build up the polymer chain.
What are constituents of food
proteins and carbohydrates
Describe proteins in comparison with nylon
possessing the same (amide) linkages as nylon but with different units
Describe the structure of proteins
Possessing the same (amide) linkages as nylon but with different units.
Describe the hydrolysis of proteins to amino acids.
For our body to make use of the proteins we eat, they need to be broken down again to amino acids through a process known as hydrolysis . This is the breaking apart of a macromolecule of protein at the amide bond and the addition of water, producing their monomers.
Describe complex carbohydrates
A large number of sugar units (diols) joined together by condensation polymerisation, e.g. a polyester with –O- linkages
Describe the hydrolysis of complex carbohydrates (e.g. starch), by acids or enzymes to give simple sugars
when we eat carbohydrates, our bodies need to break them down. This happens by a hydrolysis process using acids (like hydrochloric acid) and enzymes, such as amylase, that are found in our digestive system. This is essentially the reverse of condensation polymerisation and involves the addition of a water molecule by breaking the polymer chain apart at the –C–O–C– bond between the two monomer units. Then they revert to simple sugars
Describe the fermentation of simple sugars to produce ethanol (and carbon dioxide).
There are two main intermediary substances formed during the fermentation process, known as pyruvates and acetaldehydes. These two substances are necessary to be created before the final ethanol product is formed
Describe, in outline, the usefulness of chromatography in separating and identifying the products of hydrolysis of carbohydrates and proteins
We can use this chromatography effectively to identify, for example, which amino acids are present after a protein chain has been hydrolysed and broken down The R f value for each dot is calculated and is compared to the known R f value for each of the twenty amino acids to identify which amino acids are present. This same principle of molecules with slightly different structures having different affinities for the solution they are placed in during chromatography can be applied for separating and identifying the presence of different types of glucose molecules.
Amino acids and simple sugars are colourless, so a locating agent will be needed to see them.
Understand that different polymers have different units and/or different
- Each polymer is made from a certain monomer or monomers, therefore different polymers have different units and/or different linkages (depending on how the monomer(s) join up to form the polymer)
- monomers can be different lengths or can have different groups attached
- can have a C-C linkage, ester linkage or amide linkage
Describe the pollution problems caused by non-biodegradable plastics
Unable to decompose, because the polymers that form these plastics are inert / unable to react. Therefore, microorganisms and bacteria are unable to break them down. Thus, the landfills are bad for the environment as the plastics will remain in the ground, unable to break down/decompose and they produce toxic gases when they are burned and carbon dioxide, which adds to global warming
