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63 Cards in this Set
- Front
- Back
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Empirical Formula
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Empirical formula refers to the simplest whole number ratio of atoms of each element present in a compound.
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Molecular Formula
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Molecular formula refers to the actual number of atoms of each element in a molecule.
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General Formula
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General formula is the simplest algebraic formula of a member of a homologous series. For example, the general formula of an alkane is C n H 2 n +2
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Structural Formula
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Structural formula is the minimal detail that shows the arrangement of atoms in a molecule. For example, butane: C H 3 C H 2 C H 2 C H 3
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Displayed Formula
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Displayed formula shows the relative positioning of atoms and the bonds between them.
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Skeletal Formula
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Skeletal formula is simplified organic formula, shown by removing hydrogen atoms from alkyl chains, leaving just a carbon skeleton and associated functional groups.
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Homologous Series
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A homologous series is a series of organic compounds that have the same functional group but with each successive member differing by C H 2.
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Functional Group
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A functional group is the group of atoms responsible for the characteristic reactions of a compound.
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State the first ten members of the alkanes homologous series.
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The first ten members of the alkanes homologous series are:
Methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane. |
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What does I.U.P.A.C. stand for?
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International Union of Pure and Applied Chemistry.
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Structural Isomers
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Structural isomers are compounds with the same MOLECULAR formula but different STRUCTURAL formulae.
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Stereo-isomers
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Stereo-isomers are compounds with the same STRUCTURAL formula but with a different arrangement in space (usually around a carbon-to-carbon double bond).
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E/Z isomerism
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E/Z isomerism is a type of stereoisomerism, in which different groups attached to each carbon of a (carbon-to-carbon) double bond may be arranged differently in space. This is because of the restricted rotation of the double bond.
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Cis-trans isomerism
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Cis-trans isomerism is a special type of E/Z isomerism in which there is a non-hydrogen group and hydrogen on each carbon of a carbon to carbon double bond.
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Cis (Z) Isomer
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The cis isomer (Z isomer) has the hydrogen atoms on each carbon on the same side.
Cis, like cisgender - same. |
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Trans (E) isomer
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The trans isomer (E isomer) has the hydrogen atoms on each carbon on different sides.
Trans, like transgender, different. |
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What are the different types of covalent bond fission?
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The different types of covalent bond fission are homolytic and heterolyric fission.
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Homolytic Fission
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Homolytic fission is the breaking of a covalent bond with one of the bonded electrons going to each atom, forming two radicals.
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Heterolytic Fission
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Heterolytic fission is the breaking of a covalent bond with both of the bonded electrons going to one of the atoms, forming a cation (positive charge) and an anion (negative charge).
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Radical
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A radical is a species with an unpaired electron.
Radicals are highly reactive. A radical is usually represented by a 'dot' written next to the species to represent the unpaired electron. |
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Nucleophile
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A NUCLEOPHILE IS AN ELECTRON PAIR DONOR.
A nucleophile is a reactant that attacks an electron-deficient carbon atom, donating an electron pair. They are often negative ions with a lone pair of electrons, including electronegative atoms with a lone pair of electrons and a slight negative charge. |
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Electrophile
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AN ELECTROPHILE IS AN ELECTRON PAIR ACCEPTER.
An electrophile is a reactant that attacks an area of high electron density, accepting an electron pair. Electrophiles are often positive ions. Some molecules can act as electrophiles, these often include atoms with a slight positive charge (δ+). |
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Addition Reaction
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An addition reaction is a reaction in which a reactant is added to an unsaturated molecule to make a saturated molecule.
In an addition reaction, two reactants combine together to make one product. |
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Substitution Reaction
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A reaction in which an atom of group of atoms is replaced with a different atom or group of atoms.
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Elimination Reaction
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An elimination reaction is the removal of a molecule from a saturated molecule to make an unsaturated molecule.
In an elimination reaction, one reactant reacts to form two products. |
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Percentage Yield
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% Yield = (the actual amount, in moles, of product) divided by (the theoretical amount, in moles, of product) multiplied by 100.
actual/theoretical *100 |
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Atom economy
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Atom economy = (molecular mass of the desired products) divided by (the sum of the molecular masses of all products) multiplied by 100.
molecular mass of desired product / molecular mass of all products *100 |
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What are the factors that limit percentage yield?
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Equilibrium reached resulting in incomplete reaction.
Side reactions leading to by-products. Impure reactants. Reactants or products left behind on apparatus. Separation/purification resulting in loss of some of the product. |
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Why are substitution reactions less efficient than addition reactions?
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Substitution reactions have an atom economy of less than 100%. A large proportion of the starting atoms are converted into waste. An atom or group of atoms is replaced with a different atom or group of atoms, resulting in waste product.
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What are the benefits of developing chemical processes with a high atom economy, in terms of fewer waste materials?
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Reduces costs: companies will save money from not having to treat hazardous waste.
Reduce space occupied in landfill sites. Less overall chemical waste. Less damage to the environment. |
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What is the difference between percentage yield and atom economy?
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Percentage yield tells you the efficiency of converting reactants into products.
Atom economy tells you the proportion of desired products compared with all the products formed. |
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Why do addition reactions have an atom economy of 100%
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In an addition reaction, a reactant is added to an unsaturated molecule. All of the reactant molecules are converted into the desired product, so the atom economy is 100%.
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Organic compound
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An organic compound is a compound that contains the element carbon.
A carbon atom can form a single, double or triple bond with another carbon atom. A single carbon atom as 4 outer shell electrons. |
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Hydrocarbon
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A compound containing only hydrogen and carbon.
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Saturated hydrocarbon
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A hydrocarbon with single bonds only.
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Unsaturated hydrocarbon
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A hydrocarbon containing carbon-to-carbon multiple bonds. For example, the carbon-to-carbon double bonds in alkenes.
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Aliphatic and alicyclic hydrocarbons
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In aliphatic hydrocarbons, carbon atoms are joined together in straight (unbranched) or branched chains.
In alicyclic hydrocarbons, carbon atoms are joined together in a ring structure. |
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What is an alkane?
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Alkanes are the homologous series with the general formula C n H 2 n +2
Alkanes are saturated straight-chain hydrocarbons with single carbon-to-carbon bonds only. |
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Explain the tetrahedral shape around each carbon atom in alkanes.
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In alkanes each carbon atom is attached to four other atoms. Each carbon atom has a tetrahedral shape with a bond angle of 109.5 degrees.
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What is the general formula of an alcohol?
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The general formula of an alcohol is C n H 2 n + 1 O H
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As the number of carbon atoms in a straight chain alkane inceases, so does the boiling point. Why?
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van der Waal's forces are small in small molecules but increase as molecules get bigger.
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Why do straight chain alkanes have higher boiling points than branched chain alkanes?
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van der Waal's forces are smaller for shorter molecules. They operate in distances between one molecule and its neighbours. It's difficult for short fat molecules (branched molecules) to lay as close together as small thin ones (unbranched).
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van der Waal's forces
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Very weak attractive forces between induced dipoles in neighbouring molecules.
van der Waal's forces exist between all molecules. They are very small temporary dipoles. |
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What is combustion?
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Combustion is an exothermic reaction between a fuel and an oxidising agent. It produces carbon dioxide (C O 2) and water (H 2 O). Energy is usually released in the form of heat and light.
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Describe the combustion of alkanes.
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Short chain alkanes are very useful as clean fuels. They burn in plentiful supply to produce carbon dioxide and water.
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If a hydrocarbon produces black smoke as it burns, it indicates...
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If a compound burns with black smoke, it indicates incomplete combustion. The formation of carbon (soot) results in black smoke.
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If a hydrocarbon burns with a yellow flame, it indicates...
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Provided combustion is complete, hydrocarbons burn with a blue flame. If a hydrocarbon burns with a yellow flame, it indicates incomplete combustion.
Combustion tends to be less complete as the number of carbon atoms in the molecules increases. |
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What is incomplete combustion?
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When things burn with a limited supply of oxygen, they will likely undergo incomplete combustion. This results in the formation of carbon monoxide rather than carbon dioxide. C O is a colourless, odourless and poisonous gas.
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What causes incomplete combustion?
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Incomplete combustion is the result of a limited oxygen supply.
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Why is incomplete combustion dangerous?
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Carbon monoxide is poisonous. It inhibits respiration by preventing haemoglobin in red blood cells from binding with oxygen, resulting in the body's tissues becoming starved of oxygen. This can be fatal.
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Cracking
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Cracking refers to the breaking down of long-chained saturated hydrocarbons to form a mixture of shorter chained alkanes and alkenes.
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Cracking is a thermal decomposition reaction. It requires...
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A catalyst and heat. Today, most catalytic cracking uses a zeolite catalyst and about 450 degrees Celsius.
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State the useS of the short chain alkanes and alkenes that result from cracking.
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Short chain alkanes are used as fuels.
Short chain alkenes are used in polymer production and to make alcohols. |
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Catalyst
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A catalyst is a substance that increases the rate of a chemical reaction without being used up in the process.
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When cracking takes place, a large number of products are formed. Why is this?
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Any carbon-to-carbon bond in the chain can break, resulting in chains of different lengths.
The carbon chain can break in many different places. |
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Why does the petroleum industry process straight chain alkanes into cyclic hydrocarbons?
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Cyclic hydrocarbons promote efficient combustion. They are less likely to produce pre-ignition.
Cyclic hydrocarbons are more efficient fuels. They are easier to burn - they combust more easily. |
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What is crude oil?
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Crude oil is a mixture of many different hydrocarbons, most of which are alkanes. Crude oil is separated into fractions, many of which can be used as fuels.
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What is Fractional distillation?
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The separation of the components in a liquid mixture into fractions which differ in boiling point (and hence chemical composition) by means of distillation, typically using a fractionating column. Products can be used as fuels.
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Describe the process of fractional distillation.
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1. The crude oil is vapourised.
2. The vapour is passed into a column that is hot at the bottom and cool at the top. 3. The vapour rises and condenses at the appropriate level. Separation is based on the different boiling points of alkanes. |
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State the disadvantages of using fossil fuels.
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Fossil fuels are non-renewable - they take millions of years to form.
Burning fossil fuels releases carbon dioxide into the atmosphere, contributing to the greenhouse effect, resulting in global warming and climate change. |
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Why is it important to develop renewable plant-based fuels such as alcohols and biodiesel?
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Fossil fuels will run out eventually.
A disadvantage to renewable plant-based fuels: The desirability of renewable fuels by rich countries may lead to problems of food supply for countries supplying the crops for fuel. |
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Glucose ferments to produce bioethanol and carbon dioxide. What are the essential conditions for this process?
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Yeast. Conditions of around 30 degrees C.
In the presence of oxygen, yeast respires aerobically to produce carbon dioxide and water. Without oxygen, yeast ferments to produce alcohol (ethanol, C2H5OH). Therefore, anaerobic conditions are required. |
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What is an alkene?
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A homologous series of unsaturated hydrocarbons containing a carbon-to-carbon double bond.
The general formula of the alkenes is C n H 2 n. |
