10.4.1 The Haber process Used to manufacture ammonia to produce nitrogen-based fertilisers Equation Nitrogen + hydrogen ⇌ ammonia N2 (g) + 3H2 (g) ⇌ 2NH3 (g) Purified gases passed over… (conditions) Iron catalyst High temp - 450°C High pressure - 200atm Explain why...
10.3.1 Corrosion and its prevention Corrosion Destruction of materials by chemical reactions with substances in the environment Eg rusting 4Fe + 3O2+ 6H2O → 4Fe(OH)3 How to prevent corrosion? Surface coating Sacrificial protection Apply a coating – acts as barrier Eg...
10.2.1 Life cycle assessment (LCAs) Life cycle assessments (LCAs) are carried out to assess the environmental impact of products in each of these stages: Extracting and processing raw materials Manufacturing and packaging Use and operation during its lifetime Disposal...
10.1.1 Using the Earth's resources and sustainable development Human use of Earth’s resources – provide warmth, shelter, food & transport Natural resources, supplemented by agriculture – provide food, timber, clothing & fuels Finite resources, ocean,...
9.3.1 Atmospheric pollutants from fuels 9.3.2 Properties and effects of atmospheric pollutants Pollutant How it’s produced Effects Solution Carbon dioxide CO2 & water vapour H2O(g) Complete combustion of hydrocarbon fuels Eg CH4 + 2O2 → CO2 + 2H2O Greenhouse gases...
9.1.1 The proportions of different gases in the atmosphere Nitrogen - 80% Oxygen – 20% Small proportions of other gases, including carbon dioxide, water vapour & noble gases There is not much O2 in the atmosphere of Mars. Suggest why (1) Mars has no plants The...
9.2.1 Greenhouse gases Maintain temp on Earth high enough to support life Greenhouse gases – H2O(g), CO2, CH4 Describe greenhouse effect in terms of the interaction of short and long wavelength radiation with matter Energy from sun passes through atmosphere as short...
8.1.1 Pure substances In Chemistry, pure substance is... Single element or compound Not mixed with any other substance Eg vaporised iodine Pure elements and compounds Melt & boil at specific temp Melting & boiling point data → distinguish pure substances from...
8.2.1 Test for hydrogen 8.2.2 Test for oxygen 8.2.3 Test for carbon dioxide 8.2.4 Test for chlorine Gases Test Positive Result Hydrogen (H2) Burning spit held at the open end of a test tube of gas Burns rapidly with a squeaky pop sound Oxygen (O2) Insert glowing...
8.3.1 Flame tests Positive Ion (Cation) Test Positive Result Lithium, Li+ Flame Test Clean wire loop by dripping it in HCl Place loop in solid of dry sample A Place loop in blue Bunsen burner Crimson Red Sodium, Na+ Yellow Potassium , K+ Lilac Calcium, Ca2+ Orange-Red...
7.3.1 Addition polymerisation Alkenes can be used to make polymers eg poly(ethene) by addition polymerisation In addition polymerization reactions, many small molecules (monomers) join tgt to form large molecules (polymers) Some carrier bags are made from...
7.2.1 Structure and formulae of alkenes Alkenes Hydrocarbons with double C=C bond General formula: CnH2n Why are alkene molecules unsaturated? They contain 2 fewer hydrogen atoms than alkane with same no of carbon atoms What are alkenes used? Produce polymers As...
7.1.1 Crude oil, hydrocarbons and alkanes Define crude oil. (2) Finite resource found in rocks Remains of ancient biomass consisting mainly of plankton that was buried in mud Mixture of a very large no. of compound (hydrocarbons) Define hydrocarbons (2) Molecules made...
6.2.1 Reversible reactions Reversible reaction Products of reaction can react to produce original reactants Under certain conditions Occur in apparatus which prevent escape of reactants & products A + B ⇌ C + D Direction of reversible reactions can be changed by...
6.1.1 Calculating rates of reactions 6.1.2 Factors which affect the rates of chemical reactions Collision theory & factors that affect the rate How does increase in temperature affect the rate of reaction? ↑ KE – particles move faster ↑ frequency of successful...
5.2.1 Cells and batteries Cells – chemical react → produce electricity Voltage produced depend on type of electrode & electrolyte Simple cell – connect 2 different metals in contact with electrolyte Batteries – 2+ cells connected in series to provide greater...
5.1.1 Energy transfer during exothermic and endothermic reactions 5.1.2 Reaction profiles 5.1.3 The energy change of reactions (HT only) Exothermic Eg thermal decomposition, citric acid + NaHCO3 Take in energy from surroundings Temp ↓ Products more energy than...
4.3.1 The process of electrolysis Electrolysis When ionic substance is molten (electrolyte) Ions move freely & pass electric current +ve ions to move to -ve electrode (cathode) -ve ions to move to +ve electrode (anode) Ions are discharged at electrodes...
4.1.1 Metal oxides Metal oxides Metal(s) + oxygen(g) → metal oxides(s) OIL RIG Oxidation is loss of electrons, gain of O2 Reduction is gain of electrons, loss of O2 (using carbon) 4.1.2 The reactivity series Reactivity series – need to memorize Please send lions,...
Important formulae Acid + alkali / base → salt + water Acid + metal → salt + hydrogen Acid + metal oxide → salt + water Acid + metal hydroxide → salt water Acid + metal carbonate → salt + water + carbon dioxide 4.2.1 Reactions of acids with metals (Reactivity: see...
1 mole of gas = 24 dm3 1 dm3 = 1000 cm3 1 m3 = 1000 cm3 A helium balloon has a volume of 48000 cm3. Calculate the moles of helium in the balloon. (2) All the formulae
mole = concentration × volume n = cv n = number of moles (mol) c = concentration of solution (mol/dm-3) v = volume of solution (dm-3) 1dm3 = 1000cm3
3.3.1 Percentage yield Percentage yield For a Stage 2 reaction the percentage yield was 92.3% The theoretical maximum mass of titanium produced in this batch was 13.5 kg. Calculate the actual mass of titanium produced. (2) Factors that affect % yield Not all reactant...
3.2.1 Moles (HT only) Moles Avogadro constant = 6.02 × 1023 No of molecules = mole × 6.02 × 1023 Mass of 1 mol of a substance = relative atomic mass (Ar) in grams if substance is an element = relative formula mass (Mr) in grams if substance is a compound Reacting...
3.1.1 Conservation of mass and balanced chemical equations Law of conservation of mass No atoms are lost or made during a chemical reaction So mass of products = mass of reactants Total mass before = 127.6 + 126.86 = 254.46 Total mass after = 153.09 + 101.37 = 243.46...
2.4.1 Sizes of particles and their properties Nanoparticles 1-100nm in size, a few hundred atoms thick High SA:vol ratio Smaller than fine particles (PM5) – diameters between 100-2500nm (1×10-7-2.5×10-6m) Coarse particles (PM10) – diameters between 1×10-5-2.5×10-6m –...
2.2.1 The three states of matter Properties of Solids, Liquids and Gases Solid Liquid Gas Close together in regular pattern Strong intermolecular force of attraction Vibrate at fixed position Fixed shape & volume Close together in random pattern Further apart...
2.3.1 Diamond 2.3.2 Graphite 2.3.3 Graphene and fullerenes (See 2.1.4 Covalent bonding)
2.1.1 Chemical bonds (See 2.1.2-2.1.5 below) 2.1.2 Ionic bonding Ionic bonding Transfer of electrons between metal & non-metal Electrostatic force of attraction in all directions between oppositely charged ions Occurs in ionic compound Produce giant ionic...
1.3.1 Comparison with Group 1 elements What are the physical differences between group 1 & transition elements? (3) Group 1 Transition metals Low melting point Low density Soft High melting point High density Strong, hard What are the chemical differences between...
1.2.1 The periodic table Arrangement – order of increasing atomic no Elements with similar properties are in columns, aka groups Why is the table called periodic table? Similar properties occur at regular intervals Why are the elements in the same group? Same no of e-...
1.1.1 Atoms, elements and compounds Atom – smallest part of an element that can exist Element • Substance made of 1 type of atom • Cannot be broken down chemically into simpler substance Compound • 2 or more elements chemically bonded in fixed properties • Form /...
The Haber process The Haber process is about the production of ammonia (NH3) – the reversible reaction is: N2 + 3H2 <- -> 2NH3 + (heat) Volume will be higher on the left as there is two sets of molecules (volume includes space between them) – also the reaction...
Covalent substances: Giant Covalent These are similar to giant ionic structures – but no charged ions All the atoms are bonded to each other by strong covalent bonds This means they have very high melting and boiling points They don’t conduct electricity – except for...
RATES OF REACTION Things that effect rates of reaction Concentration (pressure/ strength of the liquid) Temperature Presence of a catalyst Surface area of solids
Ways to measure the rate of reaction How quickly the reactants are used up How quickly the product is formed Rate of reaction = How quickly the reactants are used up /How quickly the product is formed ...
Experiments Reaction of hydrochloric acid and marble chips (see pg. 109) – You can use the gas syringe method to measure the rate of the reaction. Repeat the experiment with the same mass of chips but different sizes of them to change the surface area. – The smaller...
COLLISION THEORY Collision theory says that the rate of reaction depends on the amount of collisions and how hard the particles collide. The harder the collisions and the more of them the faster the rate of reaction. Temperature – More energy of the particles...
Covalent Bonding – sharing electrons Non-metals prefer to share electrons through covalent bonds They only share atoms on their outer shells – and this makes them feel like they have full outer shells like a noble gas Each atom involved will make up enough covalent...
Covalent Substances: Simple Molecular Simple molecular structures Substances with covalent bonds can form simple molecules The atoms form very strong bonds covalently – these form strong molecules The forces of attraction between these molecules are very weak For...
Chemistry – Ionic and covalent bonding, polymers and materials Atoms and Compounds Atomic number and mass number describe an atom: Compounds are when two are more atoms chemically join together – e.g. carbon dioxide – they are hard to separate Isotopes:...
Acids and Alkalis pH scale 0- 14 : Acids – 0-6 Neutral – 7 Alkalis – 8-14 Universal indicator Red to yellow is acid green is neutral blue to purple is alkali Acids and alkalis neutralise each other Acid (pH less than 7) in water...
Oxides, Hydroxides, ammonia Metal oxides and hydroxides are bases Some dissolve is water and therefore are alkalis But they still can react with acids even if they don’t dissolve in water Acid + metal oxide = salt + water Acid + metal hydroxide = salt + water Ammonia...
Making salts Most chlorides, sulphates and nitrates (salts) are soluble in water – notable exceptions are lead chloride, lead sulphate and silver chloride Most oxides and hydroxides are insoluble The method to make a soluble salt depends are whether the base is...
Relative Formula mass Atomic Mass = A Ar = the relative atomic mass (usually the same as the atomic mass number) When an element has more than one isotope then the relative atomic mass number is the weighted average Weighted mass means that it is measured by how much...
Calculating the percentage mass of an element in a compound The percentage is the: Ar x number of atoms for that element in the formula / the Mr x 100 E.g. MgCl2 (Mg Ar = 24 Cl Ar = 35.5) Mr = 24 +(35.5 x 2) = 95 The percentage that is chlorine is: 5 x 2 / 95...
Calculating masses in reactions – 3 important steps Write out a balanced equation Work out the Mr Divide to get one and multiply to get all g. What mass of magnesium oxide is produce when 60g of magnesium is burnt in air Step 1: Write a balanced equation = 2Mg + O2 =...
Chemical Analysis using paper chromatography Artificial colouring may be separated by chromatography Food colouring may contain one dye or a mixture of dyes You place the food colouring (a few drops) in small cup with a few drops of solvent (water, ethanol etc.) Put...