Exam

General Notes

• Spelling does not matter as long as meaning is not changed

• If done know what observation says bubbles

• What should the person do to make the experiment better: Repeat

Paper 1

2 Hours

Paper 2

1 hour 15 min

Ammonia in NH3 and Ammonium is NH4+

Inorganic Chemistry

(2a)

(2g) Acids, bases, and salt preparations

2.34 know the general rules for predicting the solubility of ionic compounds in water: • common sodium, potassium and ammonium compounds are soluble • all nitrates are soluble • common chlorides are soluble, except those of silver and lead(II) • common sulfates are soluble, except for those of barium, calcium and lead(II) • common carbonates are insoluble, except for those of sodium, potassium and ammonium • common hydroxides are insoluble except for those of sodium, potassium and calcium (calcium hydroxide is slightly soluble).

2.35 understand acids and bases in terms of proton transfer

• Acids: proton donors because they have H+ ions

• Bases: proton acceptors as they ionize

2.36 understand that an acid is a proton donor and a base is a proton acceptor

2.37 describe the reactions of hydrochloric acid, sulfuric acid and nitric acid with metals, bases and metal carbonates (excluding the reactions between nitric acid and metals) to form salts

2.38 know that metal oxides, metal hydroxides and ammonia can act as bases, and that alkalis are bases that are soluble in water

2.39 describe an experiment to prepare a pure, dry sample of a soluble salt, starting from an insoluble reactant

Preparation of soluble salt from insoluble base:

1. Mix the insoluble base and the acid

2. Add excess solid (to ensure all the acid has reacted)

3. Filter to remove the excess solid (you are not left with a solution of your product dissolved in water)

4. Evaporate most of the water until crystalls begin to appear

5. Leave to allow to crystallize slowly

6. Dry the crystals in warm oven (dry oven to dry faster)

• It is important to know that excess solid is added to make sure ALL acid has reacted

2.40C describe an experiment to prepare a pure, dry sample of a soluble salt, starting from an acid and alkali

Preparation of a soluble salt from an acid and alkali:

1. Use a pipette to transfer the acid to a conical flask

2. Add a few drops of indicator

3. Place the alkali solution in the burette

4. Add the alkali from the burette into the acid, until the solution is neutral. Record the volume.

5. Repeat but without indicator using volume from step 4 (indicator will be impurity)

6. Evaporate most of the water until crystals begin to appear

7. Leave to allow to crystallise slowly

8. Dry the crystals in a warm oven

Step 1-4: to find the exact volume needed to netralise which is shown through the indicator

2.41C describe an experiment to prepare a pure, dry sample of an insoluble salt, starting from two soluble reactants

Preparation of an insoluble salt from two soluble (solution):

1. Mix the two solutions, a precipitate will form (the precipitate is the insoluble product)

2. Filter the mixture to separate the solid

3. Wash the solid with distilled water to remove impurities

4. Leave the solid on filter paper to dry

5. Dry the crystals in a warm oven

6. Allow to dry to constant mass

2.42 practical: prepare a sample of pure, dry hydrated copper(II) sulfate crystals starting from copper(II) oxide

Method:

2.43C practical: prepare a sample of pure, dry lead(II) sulfate

Organic Chemistry

(4a) Introduction

4.1. Know that a hydrocarbon is a compound of hydrogen and carbon only

Matching its name a hydrocarbon is a compound that is made of of however many hydrogen and carbon ONLY

4.2. Understand how to represent organic molecules using empirical formulae, molecular formulae, general formulae, structural formulae, and displayed formulae

• Empirical Formula: The simplest possible ratio of the atoms/elements in the molecule

  • e.g. Ethane is C2H6 but its empirical formula is CH3

• Molecular Formula: The actual “formula“ of the molecule, shows the actual number of atoms

  • e.g. Butene is C4H8

• General Formula: The ratio of the atoms in a family of compounds in terms of “n“

  • Alkandes general formula is C_nH_2n+2 while Alkenes general formula is C_nH_2n

• Structural Formula: Displays enough information to make the structure clear but does not show the bonds

  

• Displayed Formula: shows the spatial arrangement of all atoms, molecule, and bonds

  

4.3. Know what is meant by the terms homologous series, functional group and isomerism

• Homologous Series: A collection/series/family of organic compounds that have the same chemical properties due to having the same functional group

• All compounds within the same homologous series have:

  • The same general formula

  • The same functional group

  • Similar chemical properties

  • Physical properties that change gradient

  • The difference between each consecutive member is CH₂

• Functional Group: A group of atoms bonded together in a very specific arrangement that influences what homologous series they are a a part of (the part of the compoud that makes it that specific homologous series/ the characteristic that makes you part of the homologous series)

• Isomer: Compounds that have the same molecular formula but different displayed formula

4.4. Understand how to name compounds relevant to this specification using the rules of International Union of Pure and Applied Chemistry (IUPAC) nomenclature students will be expected to name compounds containing up to six carbon atoms

Naming an organic compound has two parts

1. The number of carbon atoms present in the compound

2. The homologous series it is part of

4.5. understand how to write the possible structural and displayed formulae of an organic molecule given its molecular formula

If the molecular formula of a compound is C₂H₆, structural formula is CH₃CH₃

4.6. understand how to classify reactions of organic compounds as substitution, addition, and combustion knowledge of reaction mechanisms is not required

• Substitution: a reaction that takes place when one functional group is replaced by another

  • Methane reacts with bromine under ultraviolet light

    CH₄    +    Br₂       →            CH₃Br   +    HB

    Methane + Bromine   →   Bromomethane + Hydrogen Bromide

• Addition: a reaction that takes place when two or more molecules combine to form a larger molecule with no other product

  • Bromine will react with ethene and the bromine molecule will react and add across the double bond of the ethene

    C₂H₄     +       Br₂         →         C₂H₄Br₂

    Ethene   +   Bromine   →   Dibromoethane

• Combustion: a reaction where an organic substance reacts with oxygen to form carbon dioxide and water

  • Complete Combustion: If there is an unlimited supply of oxygen, the products are carbon dioxide and water:

    CH₄   +   2O₂   →   CO₂   +   2H₂O

    C₃H₈   +   5O₂   →   3CO₂   +   4H₂O

  • Incomplete combustion: If there is a limited supply of oxygen, the products are carbon monoxide and water:

    CH₄   +   O₂   →   CO   +   2H₂O

(4b) Crude Oil

4.7. know that crude oil is a mixture of hydrocarbons

• Crude Oil: a mixture of different hydrocarbons called fractions (together the substance is not very useful)

  • A finite resource

4.8. describe how the industrial process of fractional distillation separates crude oil into fractions

• The fractions in crude oil are separated through the process of fractional distillation.

  • The size and length of each hydrocarbon molecule determine which fraction it is separated into

1. Inside the fractional column, the crude oil is heated

2. The oil evaporates up the column

3. The oil condenses as it goes up the column

   1. The hydrocarbons with the highest boiling point condense first, at the bottom of the column (bigger)

   2. Hydrocarbons with the lowest boiling point condense last, at the top of the column (small)

4.9. know the names and uses of the main fractions obtained from crude oil: refinery gases, gasoline, kerosene, diesel, fuel oil and bitumen

From Top to Bottom (low BP to high BP)

• Refinery Gases

  • Domestic Heating

  • Cooking

• Gasoline/Petrol:

  • Fuel for cars

• Kerosene:

  • Aircratf fuel

• Diesel:

  • Fuel for cars and buses

• Fuel Oil:

  • Fuel for large ships and power stations

• Bitumen (Bottom): Bitume for roads and roofs

4.10 know the trend in colour, boiling point and viscosity of the main fractions

• Viscosity: how easily can the liquid flow. The number of hydrocarbons increases → attraction between hydrocarbons increases → liquid becomes more vicious

• Colour: As carbon chain length increases → colour get darker (thicker)

• MP and BP: As molecules get larger → intermolecular attraction becomes greater → more heat is needed to seperate the molecules → increased BP and MP

• Volatility: tendency of a substance to vaporise. Increased molecular size → hydrocarbon liquid becomes less volatile (because the intermolecular attraction increases with increased size of molecules)

Sum: As you go up the column BP and viscosity decreases

4.11 know that a fuel is a substance that, when burned, releases heat energy

• Fuel: substance that releases heat energy when burned

4.12 know the possible products of complete and incomplete combustion of hydrocarbons with oxygen in the air

4.13 understand why carbon monoxide is poisonous, in terms of its effect on the capacity of blood to transport oxygen references to haemoglobin are not required

4.14 know that, in car engines, the temperature reached is high enough to allow nitrogen and oxygen from air to react, forming oxides of nitrogen

4.15 explain how the combustion of some impurities in hydrocarbon fuels results in the formation of sulfur dioxide

4.16 understand how sulfur dioxide and oxides of nitrogen contribute to acid rain

4.17 describe how long-chain alkanes are converted to alkenes and shorter-chain alkanes by catalytic cracking (using silica or alumina as the catalyst and a temperature in the range of 600–700 ºC)

4.18 explain why cracking is necessary, in terms of the balance between supply and demand for different fractions

(4c) Alkanes

4.19 know the general formula for alkanes

4.20 explain why alkanes are classified as saturated hydrocarbons

4.21 understand how to draw the structural and displayed formulae for alkanes with up to five carbon atoms in the molecule, and to name the unbranched-chain isomers

4.22 describe the reactions of alkanes with halogens in the presence of ultraviolet radiation, limited to mono-substitution knowledge of reaction mechanisms is not required

(4d) Alkenes

4.23 know that alkenes contain the functional group >C=C<

4.24 know the general formula for alkenes

4.25 explain why alkenes are classified as unsaturated hydrocarbons

4.26 understand how to draw the structural and displayed formulae for alkenes with up to four carbon atoms in the molecule, and name the unbranched-chain isomers knowledge of cis/trans or E/Z notation is not required

4.27 describe the reactions of alkenes with bromine to produce dibromoalkanes

4.28 describe how bromine water can be used to distinguish between an alkane and an alkene

(4e) Alcohols

4.29C know that alcohols contain the functional group −OH

4.30C understand how to draw structural and displayed formulae for methanol, ethanol, propanol (propan-1-ol only) and butanol (butan-1-ol only), and name each compound the names propanol and butanol are acceptable

4.31C know that ethanol can be oxidised by: • burning in air or oxygen (complete combustion) • reaction with oxygen in the air to form ethanoic acid (microbial oxidation) • heating with potassium dichromate(VI) in dilute sulfuric acid to form ethanoic acid

4.32C know that ethanol can be manufactured by: • reacting ethene with steam in the presence of a phosphoric acid catalyst at a temperature of about 300 ºC and a pressure of about 60–70 atm • the fermentation of glucose, in the absence of air, at an optimum temperature of about 30 ºC and using the enzymes in yeast

4.33C understand the reasons for fermentation, in the absence of air, and at an optimum temperature

(4f) Carboxylic Acids

4.34C know that carboxylic acids contain the functional group

4.35C understand how to draw structural and displayed formulae for unbranched-chain carboxylic acids with up to four carbon atoms in the molecule, and name each compound

4.36C describe the reactions of aqueous solutions of carboxylic acids with metals and metal carbonates

4.37C know that vinegar is an aqueous solution containing ethanoic acid

(4g) Esters

4.38C know that esters contain the functional group

4.39C know that ethyl ethanoate is the ester produced when ethanol and ethanoic acid react in the presence of an acid catalyst

4.40C understand how to write the structural and displayed formulae of ethyl ethanoate

4.41C understand how to write the structural and displayed formulae of an ester, given the name or formula of the alcohol and carboxylic acid from which it is formed and vice versa

4.42C know that esters are volatile compounds with distinctive smells and are used as food flavourings and in perfumes

4.43C practical: prepare a sample of an ester such as ethyl ethanoate

(4h) Synthetic Polymers

4.44 know that an addition polymer is formed by joining up many small molecules called monomers

4.45 understand how to draw the repeat unit of an addition polymer, including poly(ethene), poly(propene), poly(chloroethene) and (poly)tetrafluoroethene

4.46 understand how to deduce the structure of a monomer from the repeat unit of an addition polymer and vice versa

4.47 explain problems in the disposal of addition polymers, including: • their inertness and inability to biodegrade • the production of toxic gases when they are burned.

4.48C know that condensation polymerisation, in which a dicarboxylic acid reacts with a diol, produces a polyester and water

4.49C understand how to write the structural and displayed formula of a polyester, showing the repeat unit, given the formulae of the monomers from which it is formed including the reaction of ethanedioic acid and ethanediol:

4.50C know that some polyesters, known as biopolyesters, are biodegradable