Notes

Laboratory Equipment

Water Properties Colourless, odourless liquid 0°C Melting Point 100°C Boiling Point V shaped or bent; 105° bond angle Molecules join via hydrogen bonding Turns anhydrous copper sulphate from white to blue CuSO4 (s) + 5 H2O (l) -> CuSO4.5H2O (s) + heat Turns...

Carbon Cycle Methane – can be sourced from natural gas trapped in oil-bearing rocks, partial decomposition of plant materials under anaerobic conditions, waste product of digestion in animals.

Air   Gas Percentage in Air Percentage in Inhaled Air Percentage in Exhaled Air Nitrogen 79 79 79 Oxygen 20 20 17 Argon 0.9 1 (with other Inert Gases) 1 (with other Inert Gases) Carbon Dioxide 0.03 Trace 4 Others 0.07 - - Water - Variable Saturated   Fractional...

Oxygen   Laboratory Preparation of Oxygen Heating Potassium Manganate (VII)   2 KMnO4 (s) -> K2MnO4 (s) + MnO2 (s) + O2  (g) purple         ->    green    +  black + colourless Decomposing hydrogen peroxide by a catalyst of manganese (IV) oxide 2 H2O2  (l)...

Nitrogen Properties Very unreactive because of its strong intramolecular nitrogen to nitrogen triple bond Will react with some substances under the right conditions Has low boiling point of -196°C Non-polar molecule with weak intermolecular attractions Has a low...

Ammonia Preparation Ammonia gas (NH3) can be conveniently prepared in the laboratory by heating together an ammonium salt with a strong alkali e.g. Ca(OH)2 (s) + 2 NH4Cl (s) -> CaCl2 (s) + 2 H2O (l) + 2 NH3 (g) Ammonia can be collected by the downward displacement...

Ammonium Compounds Ammonia – NH3; polyatomic molecule Ammonium – NH4+  ; polyatomic charged ion, only found in ammonium compounds Ammonium Salts – formed through the reaction of ammonia with the appropriate acid. They are used as fertilisers to supply nitrogen to...

Limestone Limestone – CaCO3; various forms of lime are used to put on pastures to raise the pH because many soils are naturally acidic. Intensive cropping also lowers the pH. The lime is basic so it neutralises the soil and brings the pH closer to 7.   Quicklime...

Fats and Oils   Fats – naturally occurring polyesters with the same link between ester monomers as Terylene. The chains typically contain 12 to 20 carbon atoms. Fats and oils are rich in energy and this is their normal function to us. They are also important in soap...

Polymers Polymers - very large molecules made when hundreds of monomers join together to form long chains. They have no double bonds. Synthetic Polymers (Plastics) – man-made polymers   Monomers - a molecule that can be bonded to other identical molecules to form...

Crude Oil Fossil Fuel - organic matter (once living) e.g. coal (dead plant matter), oil (dead sea creature remains). Crude oil - made of hydrocarbons. It is the result of heat and pressure on plant and (sea) animal remains over millions of years in the absence of air....

Hydrocarbons   Hydrocarbons - a substance made of Hydrogen and Carbon   Homologous Series – a series of carbon compounds differing from each other only by the addition of more CH2  groups to increase the length of the carbon chains. Isomers – different forms of...

Alkane Reactions   Combustion – alkanes burn in oxygen to form carbon dioxide and water as long as sufficient oxygen is present; if insufficient, carbon monoxide or carbon will be produced instead of carbon dioxide Substitution – alkanes will react with halogen...

Alkene Reactions   Hydrogenation - Addition by hydrogen. Alkanes are formed when the H2 adds to the alkene molecule. A catalyst of nickel or platinum is used at a temperature of about 150 °C g. CH2 = CH2 + H2 -> CH3CH3 Halogenation – Addition of bromine or other...

Purification of Copper Copper metal is readily extracted by roasting copper ores malachite (impure CuCO3) and copper pyrites (CuFeS2) to obtain Impure copper was at the anode and pure copper was at the cathode Aqueous copper(II) sulphate was the electrolyte At the...

Electroplating Metals   Electroplating – the process involving electrolysis to coat one metal with another. Often the purpose of electroplating is to give a protective coating to the metal beneath or as a decorate coat. To plate an object with a metal, the object to...

Electrolysis   Electrolysis - the passing of a direct current through a conducting solution or liquid and the resultant decomposition of the electrolyte. It uses electricity from a power source in order to cause a chemical reaction (redox). It will force the oxidation...

Selective Discharge Rules   The ease of discharge of an ion depends on several factors, including the nature of the electrode, and the nature of the electrolyte (molten/aqueous, concentrated/dilute). Cations always discharge at the cathode Anions always discharge at...

Production of Caustic Soda   Caustic Soda – a common name of sodium hydroxide. The electrolysis of a concentrated sodium chloride solution (brine) produces three products: hydrogen, caustic soda and chlorine. The Membrane Cell method – the membrane is permeable to...

Production of Aluminium   Mine the bauxite ore (a mixture of Al2O3 and SiO2 as well as other impurities such as Fe2O3) Purify the ore by dissolving it in sodium hydroxide solution. This dissolves the alumina (aluminium oxide) which is amphoteric but not the basic...

Blast Furnace   Iron is extracted from Haematite or Ironsand in a Blast Furnace A charge is a mixture of limestone, coke (carbon) and iron oxide (as well as it’s impurities, mainly consisting of SiO2) The charge is placed in the top of the blast furnace and hot air is...

Zinc from Zincblende   The ore zincblende (made mostly from Zinc Sulphide) is crushed and put into water through which air is blown. Rock particles sink and the zinc sulphide floats in a froth which is skimmed off and dried. The product of this stage is 55-75% Zinc...

Heating Metal Compounds   Hydroxide Nitrate Carbonate Potassium Stable No Reaction Decomposes 2NaNO3 -> 2NaNO2 + O2 Stable No Reaction Sodium Calcium     Decomposes Cu(OH)2 -> CuO + H2O     Decomposes 2Ca(NO3)2  -> 2CaO + 4NO2  + O2     Decomposes MgCO3 ...

Halogens   Group VII elements are known as Halogens They are non-metals They are poisonous Melting point and Boiling point will increase as it goes down the group because the size increases, meaning an increase in the strength of the Van der Wall forces holding them...

Sulfur   Sulfur – mined from solid underground deposits of elemental sulphur, extracted from fossil fuels, received from metal sulphide ores when the metal is extracted. It is used in the manufacture of sulfuric acid.   Sulfur Dioxide – is prepared from when...

Cells   Electrolyte – molten or dissolved metal compounds that conduct electricity. When electrolytes conduct electricity, ions move. Electrode – most electrodes are metals or graphite. When metals conduct electricity, valence electrons move from ion to ion, from the...

Hydrogen Fuel Cell   Hydrogen at the anode and Oxygen at the cathode combine to form water. The reduction of Hydrogen at the anode causes the lost electrons to form a current on their way to reducing oxygen at the cathode. 2 H2 -> 4 H+ + 4 e- O2 + 4 e-  -> 2 O2-...

Reactivity Series

Corrosion   Corrosion – when metals react with water and oxygen. The metal ions lose electrons to form ions. Rusting – the corrosion of iron metal to form a red-brown compound (hydrated iron (III) oxide) Covering with Protective Coat Preventing Oxidation of Metal...

Reduction of Metal Oxides   By Hydrogen: only the metals below Hydrogen in the reactivity series are reduced by using this method (mainly only CuO)   CuO (s) + H2 (g) -> Cu (s) + H2O (l) By Carbon: only the metals below Carbon in the reactivity series are...

Alloys   Alloy Mixture Use Solder 70% Tin, 30% Lead Joining wires and pipes Brass 60-95% Copper, 5-40% Zinc Taps, hose/pipe fittings, zips, screws Bronze 90% Copper, 10% Tin Ornaments, bells, bearings Mild Steel 99.5% Iron, 0.5% Carbon General structural purposes,...

Solubility of Ionic Compounds in Water   Precipitate – a solid formed in a solution.   Sparingly Soluble (SpSol) – materials have very low solubilities Hydrolyse (Hyd) – reacts with water Always Soluble Usually Soluble Usually Insoluble - All NO3 2- All SO4    ...

Identification of Cations   Add a few drops of NaOH Add excess NaOH Add Ammonia to fresh sample + NH4 No precipitate formed When warm = litmus blue - Cu2+ Blue precipitate formed - - Fe2+ Green precipitate formed - - Fe3+ Orange/Brown precipitate - - Al3+ White...

Identification of Anions   Test with red litmus Add HNO3 and Ba(NO3)2 Add dilute HNO3 and AgNO3  to fresh sample Add Al and NaOH to fresh sample; warm - CO3 Litmus turns blue - CO2 released (HNO3 only) - 2- SO4 No change Precipitate forms - - Cl- No change No...

Identification of Gases   Ammonia Turns damp litmus blue; forms white smoke when in contact with HCl fumes Carbon Dioxide Turns limewater milky Chlorine Bleaches damp litmus paper Hydrogen ‘Pops’ with lighted splint Oxygen Relights a glowing...

Physical Properties of Metals, Non-Metals and Metalloids   Metals Non-Metals Metalloids Lustre (shiny) No lustre Can be shiny or dull Good conductor of heat Poor conductor of heat Fair conductor of heat Good conductor of electricity Poor conductor of electricity Fair...

Chemical Properties of Metals and Non-Metals   Metals Non-Metals Easily loses electrons Tends to gain electrons Oxides generally basic and amphoteric Oxides generally neutral Corrodes easily

Alkali Metals   Very low density and therefore floats on water. The densities increase down the Silvery and shiny when freshly cut, however they quickly tarnish Low melting point Low boiling point The reactivity increases down the group. Since the valence...

Transition Metals   Physical Properties (compared to Group 1) Chemical Properties (compared to Group 1) Much harder Much less reactive Higher tensile strength Many have excellent corrosion resistance Higher density Show more than one valency (e.g. Fe2+  or Fe3+)...

Metals Uses   Metal Property Uses Aluminium Does not corrode Food containers Low density, unreactive Containers and packaging buildings Low density, strong, conducts Long distance wiring Low density, strong, cheap Transport vehicles Low density, conducts heat Car...

Haber Ammonia Process   Haber Process – the process by which ammonia is made from nitrogen and hydrogen. Nitrogen is obtained from air and hydrogen is obtained from methane. It follows the following equation: N2  + 3 H2  <- -> 2 NH3            ΔH = -92...

Conditions of the Haber Process   Pressure of 200 atm and Temperature between 380 and 450 °C Ground Iron catalyst to increase the rate of reaching equilibrium at the lower temperature The equilibrium mixture is cooled, allowing ammonia to liquefy and be Unused...

Rates of Reaction   Rates of reactions can be measured by the:   Time for a solid to dissolve or form Loss in Mass (gas given off) over time Volume of Gas collected per time Time for a colour to appear or disappear Collision Theory - in order for a chemical...

Acids and Bases Acid – a substance that acts as a donor of hydrogen ions Base – a substance that acts as an acceptor of hydrogen ions Alkali – soluble bases Acid Base Sour Taste Bitter Taste pH less than 7 pH greater than 7 In solution, contains hydronium ions (H3O+)...

Oxides   Oxides of metals are bases (they will react with acids to form salts) Oxides of non-metals are acids (they will react with acids and bases) Some metal oxides are amphoteric (they will react with acids and bases) Some non-metal oxides are neutral Oxide ions...

Factors affecting Equilibrium   Factor Increase of Factor Decrease of Factor   Temperature Equilibrium shifts to decrease the temperature so it shifts to the endothermic direction Equilibrium shifts to increase the temperature so it shifts to the exothermic direction...

Energy   Exothermic Reactions – when energy is lost to the surroundings during a reaction.   Energy Profile for an Exothermic Reaction – the graph shows the variation in energy during the course of a chemical reaction where heat is released. Endothermic Reactions...

Equilibrium Reactions   Irreversible Reactions – reactions that has products that cannot turn back into their reactants. Reversible Reactions – reactions that has products that can react back into the original reactants. Dynamic Equilibrium – when there is no overall...

Redox Reactions   Oxidation – the gain of oxygen; the loss of hydrogen; the loss of electrons; increase in the oxidation number Reduction – the loss oxygen; the gain of hydrogen; the gain of electrons; decrease in the oxidation number   Oxidising Agents...

Empirical Formula   Percentage composition by mass gives a ratio by mass of the elements contained in a compound This ratio by mass can be converted to a ratio by moles if the % figures (or the known mass) are divided by the respective relative atomic masses Ratios of...

Types of Reactions   Single    Displacement    -    one    element    displaced Most Metals + Water -> Metal Hydroxide + Hydrogen Gas Most Metals + Acid -> Metal Salt + Hydrogen Gas e.g. Cu + HCl -> CuCl2 + 2H A  + BC  à A       +  B   Double...

Photochemical Reactions   Photosynthesis – the conversion of water and carbon dioxide into glucose and oxygen for energy. The glucose produced is used to make sugars and starch as carbohydrates. Carbon Dioxide + Water -> Glucose + Oxygen Gas 6 CO2          + 6 H2O ...

Avogadro’s Constant – equal volumes of all gases measured under the same conditions of temperature and pressure contain equal numbers of molecules Moles – the amount of a substance which contains 6x1023 atoms, ions or molecules. This number is called the Avogadro’s...

Calculating Ar (Relative Atomic Mass/RAM): The Ar of an element is defined as the average mass of its isotopes compared with one- twelth of the mass of one atom of Carbon 12 Carbon 12 has a mass of 12 therefore, one-twelth of the mass of one atom of Carbon 12 is 1 To...

Calculating Mr (Relative Formula Mass/Relative Molecular Mass):   To calculate the Mr of a compound, you add the mass number of each of the elements e.g. NaCl = 23 + 35 = 58 or MgBr2  = 24 + 80 + 80 = 184

Conductors   To conduct, charged particles must be present and these charged particles must be free to move. There are two types of conductors: Elements which conduct in both solid and liquid because their outer shell electrons are mobile g. metals Electrolytes...

States of Matter Matter – all the substances and materials from which the physical universe is composed   Kinetic Particle Theory – a theory which accounts for the bulk properties of matter in terms of the constituent particles. It states that: All matter is made...

Pressure of a Gas   The free moving particles of a gas will spread evenly within a container and collide with the walls. This will exert a force on the wall when it bounces When this happens on a large scale (billions of particles) there is an average force...

Ionic Compounds   Solid ionic compounds have no moving charged particles, they do not conduct Liquid and aqueous ionic compounds have free moving charged particles (ions) in solution which can carry charge under the influence of an electric   Ionic Bond Covalent...

Polar Bonds   Non-Polar Bonds – covalent bonds that involve exactly equal sharing of the bonded pair(s) of electrons (e.g. Cl with Cl, O with O) or close enough to equal sharing (e.g. C with H) that the shared pair of electrons is equidistant between the two atoms and...

Shapes of Molecules   Molecule Example Shape Bond Angle CO2 Linear O-C-O = 180° H2O Bent/V-Shaped H-O-H = 105° BF3 Triangular Planar F-B-F = 120° NH3 Pyramidal H-N-H = 107° CH4 Tetrahedral H-C-H = 109.5°     Radioactivity – when the nucleus in a radioactive atom is...

Radioisotopes and their Uses   Radioisotopes Uses Carbon – 14 Carbon Dating; When an organism dies it stops taking in new carbon atoms so the amount of carbon-14 slowly drops as the atoms decay. By measuring the radiation from the carbon-14 atoms the age of the...

Bonding   Metal + Electrons = Metallic Bonding Metal + Non-Metal = Ionic Bonding Non-Metal + Non-Metal = Covalent Bonding   Metallic Bonding:   Metallic Bond is the attraction between the metal ions and the delocalised electrons Too many atoms to count, unlike small...

Sublimation – heating of substances, in which one will sublime (I2 and CO2 will sublime)   Magnetism – takes out those things which are attracted to a magnet (Like Fe, Co and Ni).   Chromatography – substances dissolved in water (or other solvents) travel...

How the purity of a substance can be shown:   Pure Impure Melting Point Sharp Melting Point; usually high Range of temperatures Boiling Point Sharp Boiling Point; usually low Range of temperatures Chromatography One well-defined Spot on chromatogram Several spots on...

Separating Liquid/Liquid Mixtures:   Miscible – description of liquids that form a homogeneous layer when two are mixed together Immiscible – description of liquids that form two layers when two are mixed together Separating Funnel – funnel that allows the layers in...

Separating Solid/Liquid Mixtures:   Solute – the solid which dissolves in a solvent Solvent – the liquid that the solute dissolves in Solution – formed when a solute dissolves into another solvent: solute + solvent à solution   Saturated solution – a solution which...