IGCSE Chemistry Complete examination with the correct marking scheme, Exams of Chemistry

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IGCSE Chemistry Complete examination with the correct marking scheme  State the method used to obtain sand from a mixture of sand and water Answers - Correct filtration  State the method used to obtain solid copper sulfate from aqueous copper sulfate - Correct Answers crystallization  State the method used to obtain red food dye from a mixture of food dyes - Correct Answers paper chromatography  State the method used to obtain water from salt water - Correct Answers simple distillation  Draw a diagram to show equipment used in simple distillation - Correct Answers For what process is this equipment used?  State the method used to obtain kerosene from a crude oil. - Correct Answers fractional distillation  Draw the equipment used in fractional distillation in the lab - Correct Answers For what process is this equipment used?  Explain how fractional distillation is used to separate a mixture of different liquids - Correct Answers The different liquids have different boiling points  State the method used to extract the red dye from a sample of rose petals - Correct Answers dissolving  Describe how pure salt can be obtained from rock salt - Correct Answers 1) Grind rock salt into a fine powder. 2) Add powder to hot water and stir to dissolve salt. 3) Filter mixture. Salt solution passes through the filter paper leaving behind the sand. 4) Boil filtrate to evaporate some of the water. 5) Leave saturated solution to cool so that crystals of salt form. 6) Filter cold mixture to separate the crystals from the remaining solution.  Ethanol is a flammable liquid. Suggest how it could be heated safely - Correct Answers Use a water bath  Explain how a chromatogram shows that different dyes are different from each other - Correct Answers Each dyes has a different mixture  State the expression for calculating molar concentration - Correct Answers Molar concentration = Amount (in moles)/volume (in dm^³)  Which cation gives a crimson red flame color? - Correct Answers Li⁺  Which cation gives an orange flame color? - Correct Answers Na⁺  Which cation gives a lilac flame color? - Correct Answers K⁺  Which cation gives a brick red flame color? - Correct Answers Ca²⁺  Describe how you would carry out a flame test - Correct Answers Put solid onto a wire. Put into a blue flame  How would you test for the ammonium ion? - Correct Answers Add sodium hydroxide. If ammonium ions were present, ammonia gas will form which will turn damp red litmus paper blue  Predict what will happen to the equilibrium position in the following reaction when the temperature is increased. Give a reason for your prediction: CH₄(g) + H₂O(g) <-> CO(g) + 3H₂(g) ΔH = +210 kJ mol⁻1 - Correct Answers Equilibrium will move to the right because the forward reaction is endothermic  Predict what will happen to the rate of reaction in the following reaction when the temperature and pressure is increased. Give a reason for your prediction: CH₄(g) + H₂O(g) <-> CO(g) + 3H₂(g) ΔH = +210 kJ mol⁻1 - Correct Answers The rate will increase  Predict what will happen to the equilibrium position in the following reaction when the temperature is increased. Give a reason for your prediction: CO(g) + H₂O(g) <-> CO₂(g) + H₂(g) ΔH = -42 kJ mol⁻1 - Correct Answers Equilibrium will move to left the because the reaction is exothermic  Predict what will happen to the equilibrium position in the following reaction when the temperature is decreased. Give a reason for your prediction: CO(g) + 2H₂(g) <-> CH₃OH(g) ΔH = -91 kJ mol⁻1 - Correct Answers Equilibrium will move to right the because the reaction is exothermic  Predict what will happen to the equilibrium position in the following reaction when the pressure is decreased. Give a reason for your prediction: CO(g) + 2H₂(g) <-> CH₃OH(g) ΔH = -91 kJ mol⁻1 - Correct Answers Equilibrium will move to left the because there are more molecules on the left hand side  State the raw materials used in the manufacture of ammonia - Correct Answers nitrogen from air and hydrogen from natural gas  State a use for N₂ - Correct Answers making ammonia  The following reaction is used to manufacture ammonia in the Haber process: N₂ + 3H₂ -> 2NH₃ ΔH = -92KJ/mol. The reaction is carried out at 450 C but the reaction would be faster if a higher temperature ⁰ were used. Suggest why a higher temperature is not used in the Haber process - Correct Answers Yield would decrease and energy costs would increase  State the temperature used for the manufacture of ammonia by the Haber process - Correct Answers 450°C  State the pressure used for the manufacture of ammonia by the Haber process - Correct Answers 200 tam  State the catalyst used for the manufacture of ammonia by the Haber process - Correct Answers Iron  How is ammonia separated from unreacted hydrogen and nitrogen in the Haber process? - Correct Answers The reaction mixture is cooled until the ammonia condenses into a liquid  What happens to the unreacted hydrogen and nitrogen in the Haber process? - Correct Answers Recycled  State the uses of ammonia - Correct Answers manufacture of nitric acid and fertilizers  Suggest the names of two elements, other than nitrogen, that are likely to be present in NPK fertilizer - Correct Answers potassium and phosphorous  Write a chemical equation for the reaction between ammonia and nitric acid - Correct Answers NH₃ + HNO₃ -> NH₄NO₃  State the raw materials used in the manufacture of sulfuric acid. (Triple science only!) - Correct Answers Sulphur (from ores) and oxygen (from air)  Describe the manufacture of sulfuric acid by the contact process. (Triple science only!) - Correct Answers 1) Making of sulfur dioxide: S + O₂ -> SO₂, 2) Reversible step: 2SO₂ + O₂ <-> 2SO₃ (exothermic), 3) H₂SO₄ + SO₃ -> H₂S₂O₇, 4) H₂S₂O₇ + H₂O -> 2H₂SO₄  State the temperature used for the manufacture of sulfuric acid by the contact process. (Triple science only!) - Correct Answers 450°C  State the pressure used for the manufacture of sulfuric acid by the contact process. (Triple science only!) - Correct Answers 2 tam  State the catalyst used for the manufacture of sulfuric acid by the contact process. (Triple science only!) - Correct Answers Vanadium(V) oxide  State the uses of sulfuric acid. (Triple science only!) - Correct Answers manufacture of detergents, fertilizers and paints  In Chemistry, what is the meaning of the word Group? What does that tell us about the electron configuration? - Correct Answers A Group is a vertical column of similar elements (same number of electrons in the outer shell)  In Chemistry, what is the meaning of the word Period? What does that tell us about the electron configuration? - Correct Answers A Period is a horizontal row of elements (same number of electron shells)  Where are the metals in the Periodic Table? Where are the Non- Metals? - Correct Answers Metals on the left of the Periodic Table. Non-Metals on the top-right, plus Hydrogen.  If an element conducts electricity, is it a metal or a non-metal? - Correct Answers Metal  If an element doesn't conducts electricity, is it a metal or a non- metal? - Correct Answers Non-Metal  Are metal oxides acidic or basic? - Correct Answers Basic  Are non-metal oxides acidic or basic? - Correct Answers Acidic  Why do elements in the same group of the periodic table have the same chemical properties? - Correct Answers Elements in the same group of the periodic table have the same number of electrons in their outer shell  When chlorine gas is bubbled into an aqueous solution of potassium iodide, the colorless solution turns brown. Complete the following ionic equation: Cl₂(g)+ ___I⁻(as) -> 2Cl⁻(as) + ___(as) - Correct Answers Cl₂(g) + 2I⁻(as) -> 2Cl⁻(as) + I₂(as)  Describe the test for chlorine gas - Correct Answers Turns moist litmus paper white (bleaches)  Describe, in terms of electrons, the formation of sodium chloride - Correct Answers An atom of sodium loses one electron. An atom of chlorine gains one electron  Explain the term ionic bond - Correct Answers An ionic bond is the strong electrostatic attraction between oppositely charged ions  Explain, in terms of structure and bonding, why sodium chloride has a very high melting point - Correct Answers Nalco has a giant ionic structure with strong electrostatic forces between oppositely charged ions that require a lot of energy to break  Explain, in terms of structure and bonding, why magnesium oxide has a higher melting point than sodium chloride (Triple science only!) - Correct Answers Nalco and Mg both have a giant ionic structure with strong electrostatic forces between oppositely charged ions. The Ions in Mg have a charge of 2 and -2, but in Nalco the charges are 1 and -1. So the bonds in Mg require more energy to break  Explain why magnesium oxide has a higher melting point than sodium chloride. (Triple science only!) - Correct Answers Mg²⁺ and O²⁻ ions have a higher charge than sodium and chloride therefore the electrostatic forces between the ions are much stronger. This requires more energy to break.  Describe the structure of an ionic compound, e.g. Nalco. (Triple science only!) - Correct Answers A giant structure held together by the attraction between oppositely charged ions  Draw a diagram to represent the positions of the ions in a crystal of sodium chloride. - Correct Answers A - sodium ions. B - Chloride ions  Describe the formation of a covalent bond - Correct Answers The sharing of a pair of electrons between two nuclei  Give the definition of a covalent bond - Correct Answers Strong attraction between a shared pair of electrons and two nuclei  Explain the term covalent bond - Correct Answers Strong attraction between a shared pair of electrons and two nuclei  If a substance has a simple molecular structure, what physical state might it be at room temperature? - Correct Answers Gas or liquid (low melting point)  Explain why nitrogen gas, N₂, is a gas at room temperature - Correct Answers Nitrogen has a simple molecular structure with weak intermolecular forces that require little energy to overcome  Explain why Silica, Silo₂ is a solid with a high melting point - Correct Answers Silica has a giant covalent structure with many strong covalent bonds that need a lot of energy to break  Buckminsterfullerene has a simple molecular structure with weak intermolecular forces that require little energy to overcome - Correct Answers Suggest why buckminsterfullerene, C60, has a low melting point.  Draw the arrangements of atoms in diamond (Triple science only!) - Correct Answers  Draw the arrangements of atoms in graphite (Triple science only!) - Correct Answers  Explain, in terms of its structure, why graphite can act as a lubricant. (Triple science only!) - Correct Answers Graphite has weak intermolecular forces of attraction between layers. These layers can slide over each other  Explain, in terms of its structure, why graphite can conduct electricity. (Triple science only!) - Correct Answers Graphite has delocalized electrons which can move  Describe the structure of metals - Correct Answers Metals have a giant regular structure of positive ions surrounded by a sea of delocalized electrons  Define metallic bonding - Correct Answers The electrostatic attraction between a regular array of positive ions and the sea of delocalized electrons  Explain why metals are good conductors of electricity - Correct Answers Metals have delocalized electrons which are free to move  Explain why metals are ductile/malleable - Correct Answers Metals have layers of atoms that can slide over each other  Explain what is meant by electric current - Correct Answers The rate of flow of charge particles (e.g. of electrons or ions)  Why do covalent compounds (e.g. H₂O) not conduct electricity? - Correct Answers There are no charged particles that are free to move  Why do ionic compounds conduct electricity only when molten or in solution? - Correct Answers When solid the ions are held in place. When molten or in solution the ions are free to move  What type of reaction is used to form nylon? (Triple science only!) - Correct Answers Condensation polymerization  During condensation polymerization, what else forms other than the polymer? (Triple science only!) - Correct Answers A small molecule such as H₂0 or Hall  Describe, in terms of electrons, the formation of sodium chloride - Correct Answers An atom of sodium loses one electron. An atom of chlorine gains one electron  Explain why metals are good conductors of electricity - Correct Answers Metals have delocalized electrons which are free to move  Explain why metals are ductile/malleable - Correct Answers Metals have layers of atoms that can slide over each other  Explain what is meant by electric current - Correct Answers The rate of flow of charge particles (e.g. of electrons or ions)  Why do covalent compounds (e.g. H₂O) not conduct electricity? - Correct Answers There are no charged particles that are free to move  Why do ionic compounds conduct electricity only when molten or in solution? - Correct Answers When solid the ions are held in place. When molten or in solution the ions are free to move  What type of reaction is used to form nylon? (Triple science only!) - Correct Answers Condensation polymerization  During condensation polymerization, what else forms other than the polymer? (Triple science only!) - Correct Answers A small molecule such as H₂0 or Hall  Describe, in terms of electrons, the formation of sodium chloride - Correct Answers An atom of sodium loses one electron. An atom of chlorine gains one electron  Explain the term oxidation - Correct Answers Oxidation is the loss of electrons (the term is also used for the gain of oxygen)  Explain the term reduction - Correct Answers Reduction is the gain of electrons (the term is also used for the loss of oxygen)  Describe the structure of metals - Correct Answers Metals have a giant regular structure of positive ions surrounded by a sea of delocalized electrons  Define metallic bonding - Correct Answers The electrostatic attraction between a regular array of positive ions and the sea of delocalized electrons  Explain why metals are good conductors of electricity - Correct Answers Metals have delocalized electrons which are free to move  Explain why metals are ductile/malleable - Correct Answers Metals have layers of atoms that can slide over each other  Explain what is meant by electric current - Correct Answers The rate of flow of charge particles (e.g. of electrons or ions)  Why do covalent compounds (e.g. H₂O) not conduct electricity? - Correct Answers There are no charged particles that are free to move  Why do ionic compounds conduct electricity only when molten or in solution? - Correct Answers When solid the ions are held in place. When molten or in solution the ions are free to move  How could you determine if a liquid is an electrolyte? - Correct Answers Put it in a circuit including a bulb. If the bulb light then the liquid is an electrolyte  Explain what is meant by electrolysis - Correct Answers The breakdown of a substance using electricity  What is the charge of the anode? - Correct Answers positive  What is the charge of the cathode? - Correct Answers negative  What type of reaction takes place at the cathode? - Correct Answers reduction  What type of reaction takes place at the anode? - Correct Answers oxidation  Name the product formed at the anode during the electrolysis of molten copper chloride - Correct Answers chlorine  Write an equation to show the formation of the product at the cathode during the electrolysis of copper chloride - Correct Answers Cu²⁺ + 2e⁻ -> Cu  Write an equation to show the formation of the product at the anode during the electrolysis of copper chloride - Correct Answers 2Cl⁻ -> Cl₂ + 2e⁻  Suggest a suitable element for the electrode for the electrolysis of water - Correct Answers platinum  Suggest why a small amount of dilute acid is added to water before it is electrolyzed - Correct Answers increases electrical conductivity  During the electrolysis of water, oxygen gas is given off. The formation of this gas can be represented by the ionic equation: ....OH⁻ ->....H₂O + ....O₂ + ....e⁻ (Triple science only!) - Correct Answers 4OH⁻ ->2H₂O + O₂ + 4e⁻  Name the product formed at the cathode during the electrolysis of water. (Triple science only!) - Correct Answers hydrogen  The overall equation for the decomposition of water is: 2H₂O (l) -> 2H₂ (g) + O₂ (g) Use this equation to explain why the volume of hydrogen collected should be twice that of the volume of oxygen. (Triple science only!) - Correct Answers The number of moles of H₂ are twice that of oxygen  Write the ionic half-equation for the reaction that takes place at the anode during the electrolysis of lead(II) bromide - Correct Answers 2Br⁻ -> Br₂ + 2e⁻  Write the ionic half-equation for the reaction that takes place at the cathode during the electrolysis of lead(II) bromide - Correct Answers Pb²⁺ +2e⁻ -> Pub  What is a Faraday? (Triple science only!) - Correct Answers A Faraday is the charge on a mole of electrons (96500 Coulombs)  Write ionic half-equations for the reactions at the electrodes in aluminum extraction - Correct Answers Al3⁺ + 3e⁻ -> Al and 2O²⁻ -> O₂ + 4e⁻  Why does this equation represent a reduction reaction? Al³⁺ + 3e⁻ -> Al - Correct Answers Al3⁺ gains electrons  What is the formula of aluminum oxide? - Correct Answers Allow₃  In the electrolysis of Nalco, what are the anode and cathode made of? (Triple science only!) - Correct Answers anode = titanium. Cathode = iron  State the name of the gas formed at the anode during the electrolysis sodium chloride solution. (Triple science only!) - Correct Answers chlorine  State the name of the gas formed at the cathode during the electrolysis sodium chloride solution. (Triple science only!) - Correct Answers hydrogen  The solution formed after the electrolysis sodium chloride solution was tested with the indicator phenolphthalein. The indicator turned pink. Explain this result. (Triple science only!) - Correct Answers The solution is alkali (contains sodium hydroxide)  In the electrolysis of brine, why is electrode made out of titanium? (Triple science only!) - Correct Answers To prevent it reacting with the chlorine  Write the two ionic half-equations for the reactions that occur during the electrolysis of sodium chloride solution. (Triple science only!) - Correct Answers 2H⁺ + 2e⁻ -> H₂ and 2Cl⁻ -> Cl₂ + 2e⁻  State the uses of sodium hydroxide. (Triple science only!) - Correct Answers manufacture of bleach, paper and soap  State the uses of chlorine. (Triple science only!) - Correct Answers sterilizing water supplies and the manufacture of bleach and hydrochloric acid  What is the name of the colorless gas that is formed between the reaction of chlorine and hydrogen? - Correct Answers Hydrogen chloride  What is the name of the acid that is formed when hydrogen chloride gas dissolves in water? - Correct Answers Hydrochloric acid  Why Hall is acidic when dissolved in water? - Correct Answers As water is polar the Hall molecule dissociates, forming H⁺ and Cl⁻ ions.  Why Hall is not acidic when dissolved in methyl benzene? - Correct Answers As methyl benzene is not polar the molecules separate but don't form ions.  Describe the relative reactivity’s of the elements in group 7 - Correct Answers F>Cl>Br>I>At  State the color of litmus in acidic and alkaline solutions - Correct Answers acidic = red alkali = blue  State the color of phenolphthalein in acidic and alkaline solutions - Correct Answers acidic = colorless alkali = pink  State the color of methyl orange in acidic and alkaline solutions - Correct Answers acidic = red alkali = yellow  What is the pH and universal indicator color of a strong acid? - Correct Answers 1-3, red  What is the pH and universal indicator color of a weak acid? - Correct Answers 4-6, yellow  What is the pH and universal indicator color of a neutral solution? - Correct Answers 7, green  What is the pH and universal indicator color of a weak alkali? - Correct Answers 8-10, blue  What is the pH and universal indicator color of a strong alkali? - Correct Answers 11-13, purple  What is an acid? - Correct Answers An acid is a source of hydrogen ions, H⁺  What is an alkali? - Correct Answers An alkali is a source of hydroxide ions, OH⁻  acid + base -> - Correct Answers acid + base -> salt + water  acid + alkali -> - Correct Answers acid + alkali -> salt + water  acid + metal -> - Correct Answers acid + metal -> salt + hydrogen  acid + metal carbonate -> - Correct Answers acid + metal carbonate -> salt + carbon dioxide + water  sulfuric acid + copper oxide -> - Correct Answers sulfuric acid + copper oxide -> copper sulfate + water  hydrochloric acid + sodium hydroxide -> - Correct Answers hydrochloric acid + sodium hydroxide -> sodium chloride + water  hydrochloric acid + magnesium -> - Correct Answers hydrochloric acid + magnesium -> magnesium chloride + hydrogen  nitic acid + calcium carbonate -> - Correct Answers nitic acid + calcium carbonate -> calcium nitrate + carbon dioxide + water  Give the name of the substance which has the formula Hall - Correct Answers hydrochloric acid  Give the formula of sulfuric acid - Correct Answers H₂SO₄  Write the chemical equation for manufacture of ethanol by the fermentation of sugars. (Triple science only!) - Correct Answers C₆H₁₂O₆ -> 2C₂H₅OH + 2CO₂  Draw the displayed formula for ethanol, C₂H₅OH (Triple science only!) - Correct Answers Ethanol  What are the advantages/disadvantages of using the fermentation of glucose to manufacture ethanol? (Triple science only!) - Correct Answers Advantages: Uses renewable resources, e.g. sugar cane. Uses low temp and pressure therefore low energy input. Disadvantages: Uses batch process which is inefficient. Slow rate of reaction. Impure product.  What are the advantages/disadvantages of using the hydration of ethane to manufacture ethanol? (Triple science only!) - Correct Answers Advantages: Uses continuous process which is efficient. Fast rate of reaction. Pure product. Disadvantages: Uses finite resources, e.g. crude oil cane. Uses high temp and pressure therefore high energy input.  State the conditions needed for the dehydration of ethanol to ethane. (Triple science only!) - Correct Answers Hot aluminum oxide catalyst  Write the chemical equation for the dehydration of ethanol. (Triple science only!) - Correct Answers C₂H₅0H -> C₂H₄ +H₂0  What is meant by the term exothermic? - Correct Answers A reaction in which heat energy is given out (surroundings get hotter)  What is meant by the term endothermic? - Correct Answers A reaction in which heat energy is taken in (surroundings get colder)  Explain why experimental values of enthalpy change differ from theoretical values - Correct Answers Heat energy is lost to the surroundings. Not all the reactants are used up.  State the units of molar enthalpy change. (Triple science only!) - Correct Answers kJ/moll  What does the symbol ΔH mean - Correct Answers enthalpy (energy) change  Draw an energy level diagram for an exothermic reaction and use ΔH to represent the enthalpy change - Correct Answers  Draw an energy level diagram for an endothermic reaction and use ΔH to represent the enthalpy change - Correct Answers  Explain, in terms of making and breaking bonds, why a reaction could be exothermic - Correct Answers The energy need to break the bonds is less than the energy released to make the bonds  Explain, in terms of making and breaking bonds, why a reaction could be endothermic - Correct Answers The energy need to break the bonds is more than the energy released to make the bonds  Explain why carbon monoxide is dangerous to humans - Correct Answers It is poisonous because it reduces the capacity of the blood to carry oxygen  In car engines, sparks cause the formation of some gases which contribute to acid rain. What are these gases? - Correct Answers Oxides of nitrogen  Why can nitrogen react with oxygen in a car engine? - Correct Answers The temperature is very high  Describe how nitrogen oxides and sulfur dioxide contribute to acid rain - Correct Answers Nitrogen oxides created in hot car engines and sulfur dioxide released when fossil fuels are burned combine with water in the atmosphere to form acidic solutions  Write the chemical equation for sulfur dioxide dissolving in water to form acid rain - Correct Answers SO₂ + H₂O -> H₂SO₃  Describe the problems caused by acid rain - Correct Answers Acid rain damages plant life and life in lakes. It also corrodes limestone and some metals.  Explain the term homologous series - Correct Answers A homologous series is a family of compounds with 1) the same general formula 2) similar chemical properties 3) trends in their physical properties  Explain the term hydrocarbon - Correct Answers A molecule containing only hydrogen and carbon  Explain the term saturated - Correct Answers A molecule containing only single bonds  Explain the term unsaturated - Correct Answers A molecule containing a carbon-carbon double bond  Explain the term general formula - Correct Answers A formula to work out the number of each type of atom in a molecule  Explain the term isomerism - Correct Answers Molecules with the same molecular formula but with a different structure  State the general formula of alkanes - Correct Answers CnH2n+2  State the names and molecular formulae of the first 5 alkanes - Correct Answers methane (CH₄), ethane (C₂H₆), propane (C₃H₈), butane (C₄H₁₀), pentane (C₅H₁₂)  Draw the displayed formulae for methane - Correct Answers  Draw the displayed formulae for ethane - Correct Answers  Draw the displayed formulae for propane - Correct Answers  Draw the displayed formulae for butane - Correct Answers  Draw the displayed formula for the two alkanes with the molecular formula C₄H₁₀ - Correct Answers  Draw the displayed formulae for pentane - Correct Answers  Describe the trend in boiling points of the main fractions in crude oil - Correct Answers Boiling point increases as the number of carbon atoms (chain length) increase  Describe the trend in viscosity of the main fractions in crude - Correct Answers Viscosity increases as the number of carbon atoms (chain length) increase  Which fraction of crude oil has the lowest boiling point? - Correct Answers Refinery gases  What is meant by the term viscosity? - Correct Answers The viscosity of a fluid describes how easily it flows. Water has a low viscosity, it flows very easily. Crude oil has a higher viscosity than water, it does not flow very easily.  Which fraction of crude oil is the most viscous? - Correct Answers Bitumen  Explain why cracking is an important process in the oil industry - Correct Answers Cracking converts long chain hydrocarbons into short chain hydrocarbons. Crude oil contains a surplus long chains. Shorter chain hydrocarbons are in greater demand, e.g. petrol. Cracking also produces alkenes which are used in making polymers and ethanol.  What is cracking? - Correct Answers The breaking down of long- chain alkanes into alkenes and shorter-chain alkanes  State the conditions for the cracking of hydrocarbons - Correct Answers Aluminum oxide catalyst heated to 600°C  Write a chemical equation for the cracking of decani - Correct Answers C₁₀H₂₂ -> C₂H₄ + C₈H₁₈  Explain what is an addition polymer - Correct Answers An addition polymer is large molecule made by adding many small molecules (each containing a double bond) to form one much larger molecule  Explain what is a monomer - Correct Answers Monomers are the many small molecules (such as ethane) which add together to make a polymer  Describe, in terms of structure and bonding, what happens when ethane molecules are converted into poly (ethane) - Correct Answers One bond in the double bond breaks. Monomers join together to form a long chain. Polymer contains only single bonds  Draw the equation to show the formation of poly(ethane) - Correct Answers  Draw the equation to show the formation of poly(propene) - Correct Answers  Draw the displayed formula for the repeat unit of poly(ethane) - Correct Answers  Draw the displayed formula for the repeat unit of poly(propene) - Correct Answers  Draw the displayed formula for the repeat unit of poly (chloromethane). (Triple science only!) - Correct Answers  State the uses of poly(ethane) - Correct Answers Plastic bags and bottles  State the uses of poly(propene) - Correct Answers Plastic crates and ropes  State uses for poly (chloromethane). (Triple science only!) - Correct Answers Plastic piping and cable insulation  What is meant by the term biodegradable? - Correct Answers The breakdown of a substance by microorganisms  Explain why addition polymers are hard to dispose of - Correct Answers They are inert as they have strong C-C bonds. This makes them non-biodegradable.  Describe the structure of metals - Correct Answers Metals have a giant regular structure of positive ions surrounded by a sea of delocalized electrons  Define metallic bonding - Correct Answers The electrostatic attraction between a regular array of positive ions and the sea of delocalized electrons  Explain why metals are good conductors of electricity - Correct Answers Metals have delocalized electrons which are free to move  Explain why metals are ductile/malleable - Correct Answers Metals have layers of atoms that can slide over each other  In each of these pairs, which metal is more reactive: 1) sodium and copper. 2) Iron and calcium. 3) potassium and aluminum - Correct Answers 1) sodium 2) calcium 3) potassium  Explain why rusting is described as an oxidation reaction - Correct Answers iron gains oxygen (lose of electrons)  What is reduced in this equation and what is meant by reduction? WO₃ + 3H₂ -> W + 3H₂O - Correct Answers Tungsten, W losses oxygen  State the meaning of the term redox - Correct Answers A reaction involving both reduction and oxidation  State the meaning of the term oxidizing agent - Correct Answers A substance that gives oxygen or removes electrons (it is itself reduced)  State the meaning of the term reducing agent - Correct Answers A substance that takes oxygen or gives electrons (it is itself oxidized)  Describe the conditions under which iron rusts - Correct Answers oxygen and water  What is the chemical name of rust? - Correct Answers hydrated iron(III) oxide  Describe, in terms of electrons, the formation of sodium chloride - Correct Answers An atom of sodium loses one electron. An atom of chlorine gains one electron  Zinc phosphide, Nap₂ is an ionic compound. The formula of the zinc ion is Zn²⁺. Deduce the formula of the phosphide ion - Correct Answers P³⁻  What is the formula of magnesium chloride - Correct Answers MGk₂  A magnesium atom has the electron configuration 2.8.2. What is the charge on the ion? - Correct Answers 2+  State the electron configuration of a sodium ion - Correct Answers 2.8  State the electron configuration of a chloride ion - Correct Answers 2.8.8  Draw a dot and cross diagram to show the arrangement of electrons in each of the ions in sodium chloride, Nalco - Correct Answers  Draw a dot and cross diagram to show the arrangement of electrons in each of the ions in Potassium oxide, K₂O - Correct Answers  Draw a dot and cross diagram to show the arrangement of electrons in each of the ions in magnesium chloride, MGk₂ - Correct Answers  Explain the term ionic bond - Correct Answers An ionic bond is the strong electrostatic attraction between oppositely charged ions  Explain, in terms of structure and bonding, why sodium chloride has a very high melting point - Correct Answers Nalco has a giant ionic structure with strong electrostatic forces between oppositely charged ions that require a lot of energy to break  Explain, in terms of structure and bonding, why magnesium oxide has a higher melting point than sodium chloride (Triple science only!) - Correct Answers Nalco and Mg both have a giant ionic structure with strong electrostatic forces between oppositely charged ions. The Ions in Mg have a charge of 2 and -2, but in Nalco the charges are 1 and -1. So the bonds in Mg require more energy to break  Explain why magnesium oxide has a higher melting point than sodium chloride. (Triple science only!) - Correct Answers Mg²⁺ and O²⁻ ions have a higher charge than sodium and chloride therefore the electrostatic forces between the ions are much stronger. This requires more energy to break.  Describe the structure of an ionic compound, e.g. Nalco. (Triple science only!) - Correct Answers A giant structure held together by the attraction between oppositely charged ions  Draw a diagram to represent the positions of the ions in a crystal of sodium chloride. - Correct Answers A - sodium ions. B - Chloride ions  Describe the formation of a covalent bond - Correct Answers The sharing of a pair of electrons between two nuclei  Give the definition of a covalent bond - Correct Answers Strong attraction between a shared pair of electrons and two nuclei  Explain the term covalent bond - Correct Answers Strong attraction between a shared pair of electrons and two nuclei  If a substance has a simple molecular structure, what physical state might it be at room temperature? - Correct Answers Gas or liquid (low melting point)  Explain why nitrogen gas, N₂, is a gas at room temperature - Correct Answers Nitrogen has a simple molecular structure with weak intermolecular forces that require little energy to overcome  Explain why Silica, Silo₂ is a solid with a high melting point - Correct Answers Silica has a giant covalent structure with many strong covalent bonds that need a lot of energy to break  Buckminsterfullerene has a simple molecular structure with weak intermolecular forces that require little energy to overcome - Correct Answers Suggest why buckminsterfullerene, C60, has a low melting point.  Write the word and chemical equation for the decomposition of hydrogen peroxide, H2O2 - Correct Answers hydrogen peroxide -> water + oxygen 2H202 -> 2H20 + O2  State the catalyst used for making oxygen through the decomposition of hydrogen peroxide - Correct Answers manganese(IV) oxide, MnO2  Describe the laboratory preparation of oxygen from hydrogen peroxide - Correct Answers Hydrogen peroxide is added to a flask containing a catalyst of manganese oxide, MnO2. Oxygen is produced and is collected underwater.  What happens to the rate of reaction if the surface area of a solid is INCREASED? - Correct Answers Rate of reaction increases  What happens to the rate of reaction if the concentration of solutions is INCREASED? - Correct Answers Rate of reaction increases  What happens to the rate of reaction if the pressure of gases is INCREASED? - Correct Answers Rate of reaction increases  What happens to the rate of reaction if the temperature is INCREASED? - Correct Answers Rate of reaction increases dramatically  What happens to the rate of reaction if a catalyst is added? - Correct Answers Rate of reaction increases  What is meant by the term activation energy? - Correct Answers The minimum energy that the particles in collision must have if a reaction is going to occur  Explain the effects of increasing the surface area of a solid on the rate of a reaction in terms of particle collision theory - Correct  A sample of carbon contained 98.90% carbon-12 and 1.10% carbon- 13. Calculate the relative atomic mass of carbon - Correct Answers ((12x98.90)+(13x1.10))/100 = 12.01  Calculate the relative formula mass(Mr.) of zinc phosphide (Nap₂) - Correct Answers 257  Tungsten has the chemical symbol W. Suggest the chemical name of WO₃. - Correct Answers tungsten oxide  State the steps for calculating empirical formula - Correct Answers 1) mass/Ar. 2) divide by the smallest. 3) Give the ratio has a whole number. 4) State final empirical formula  What color flames to Sulphur, carbon and magnesium produce when they burn in air? - Correct Answers Sulphur = blue, Carbon = yellow/orange, Magnesium = white  Are carbon dioxide and Sulphur dioxide acidic or basic? - Correct Answers Acidic as carbon and Sulphur are non-metals  Is magnesium oxide acidic or basics? - Correct Answers Basic as magnesium is a metal.  Describe the laboratory preparation of carbon dioxide from calcium carbonate and dilute hydrochloric acid - Correct Answers Hydrochloric acid, Hall, is added to a flask contain calcium carbonate, Cacao₃. Carbon dioxide is produced and is collected using a gas syringe.  Write the word and chemical equation for the thermal decomposition of calcium carbonate, Cacao₃ - Correct Answers calcium carbonate -> calcium oxide + carbon dioxide Cacao₃ -> Cano + CO₂  State two properties of carbon dioxide - Correct Answers Soluble in water. Denser than air  Name two uses of carbon dioxide - Correct Answers Fizzy drinks. Fire extinguishers  Explain why carbon dioxide is used in fizzy drinks - Correct Answers Carbon dioxide is soluble in water  Explain why carbon dioxide is used in fire extinguishers - Correct Answers Carbon dioxide is denser that air  Why is carbon dioxide, CO₂ harmful to the environment? - Correct Answers It is a greenhouse gas and may contribute to global warming  Describe the test for carbon dioxide gas - Correct Answers Bubble the gas through limewater and see if it goes cloudy  acid + base -> - Correct Answers acid + base -> salt + water  acid + alkali -> - Correct Answers acid + alkali -> salt + water  acid + metal -> - Correct Answers acid + metal -> salt + hydrogen  acid + metal carbonate -> - Correct Answers acid + metal carbonate -> salt + carbon dioxide + water  sulfuric acid + copper oxide -> - Correct Answers sulfuric acid + copper oxide -> copper sulfate + water  hydrochloric acid + sodium hydroxide -> - Correct Answers hydrochloric acid + sodium hydroxide -> sodium chloride + water  hydrochloric acid + magnesium -> - Correct Answers hydrochloric acid + magnesium -> magnesium chloride + hydrogen  nitic acid + calcium carbonate -> - Correct Answers nitic acid + calcium carbonate -> calcium nitrate + carbon dioxide + water  Give the name of the substance which has the formula Hall - Correct Answers hydrochloric acid  Give the formula of sulfuric acid - Correct Answers H₂SO₄  Give the name of the substance which has formula HNO₃ - Correct Answers nitric acid  Where are the metals in the Periodic Table? Where are the Non- Metals? - Correct Answers Metals on the left of the Periodic Table. Non-Metals on the top-right, plus Hydrogen.  If an element conducts electricity, is it a metal or a non-metal? - Correct Answers Metal  If an element doesn't conducts electricity, is it a metal or a non- metal? - Correct Answers Non-Metal  Are metal oxides acidic or basic? - Correct Answers Basic  Are non-metal oxides acidic or basic? - Correct Answers Acidic  Name the compound formed when magnesium reacts with oxygen - Correct Answers magnesium oxide  What two observations can be made when a metal reacts with an acid? - Correct Answers Bubbles. Metal disappears.  Hydrogen and helium have both been used in balloons. State one advantage of using helium instead of hydrogen - Correct Answers Helium is not flammable  State the color of litmus in acidic and alkaline solutions - Correct Answers acidic = red alkali = blue  State the color of phenolphthalein in acidic and alkaline solutions - Correct Answers acidic = colorless alkali = pink  State the color of methyl orange in acidic and alkaline solutions - Correct Answers acidic = red alkali = yellow  What is the pH and universal indicator color of a strong acid? - Correct Answers 1-3, red  Draw the displayed formulae for ethane - Correct Answers  Draw the displayed formulae for propane - Correct Answers  Draw the displayed formulae for butane - Correct Answers  Draw the displayed formula for the two alkanes with the molecular formula C₄H₁₀ - Correct Answers  Draw the displayed formulae for pentane - Correct Answers  Draw the three isomers of pentane - Correct Answers  Write a chemical equation for the complete combustion of propane - Correct Answers C₃H₈ + 5O₂ -> 3CO₂ + 4H₂O  Recall the products of the complete combustion of alkanes - Correct Answers Carbon dioxide and water  Recall the products of the incomplete combustion of alkanes - Correct Answers Carbon, carbon monoxide, carbon dioxide and water  What is crude oil? - Correct Answers A mixture of hydrocarbons  Explain how crude oil is separated into fractions - Correct Answers Crude oil is separated by fractional distillation. Crude oil is heated and the oil evaporates. It then goes into the tower. As the vapors rise up the tower the temperature falls. Different sized fractions condense at different heights because they have different boiling points. Smaller molecules condense high up the tower. Larger molecules condense low down in the tower. Then the fractions are collected.  Recall the names of the main fractions obtained from crude oil - Correct Answers Refinery gases, gasoline, kerosene, diesel, fuel oil and bitumen  Recall a use of refinery gases - Correct Answers Bottled gas  Recall a use of gasoline - Correct Answers Fuel for cars  Recall a use of kerosene - Correct Answers Fuel for aero planes  Recall a use of diesel - Correct Answers Fuel for lorries  Recall a use of fuel oil - Correct Answers Fuel for ships  Recall a use of bitumen - Correct Answers Surfacing roads  Describe the trend in boiling points of the main fractions in crude oil - Correct Answers Boiling point increases as the number of carbon atoms (chain length) increase  Describe the trend in viscosity of the main fractions in crude - Correct Answers Viscosity increases as the number of carbon atoms (chain length) increase  Which fraction of crude oil has the lowest boiling point? - Correct Answers Refinery gases  What is meant by the term viscosity? - Correct Answers The viscosity of a fluid describes how easily it flows. Water has a low viscosity, it flows very easily. Crude oil has a higher viscosity than water, it does not flow very easily.  Which fraction of crude oil is the most viscous? - Correct Answers Bitumen  Explain why carbon monoxide is dangerous to humans - Correct Answers It is poisonous because it reduces the capacity of the blood to carry oxygen  In car engines, sparks cause the formation of some gases which contribute to acid rain. What are these gases? - Correct Answers Oxides of nitrogen  Why can nitrogen react with oxygen in a car engine? - Correct Answers The temperature is very high  Describe how nitrogen oxides and sulfur dioxide contribute to acid rain - Correct Answers Nitrogen oxides created in hot car engines and sulfur dioxide released when fossil fuels are burned combine with water in the atmosphere to form acidic solutions  Write the chemical equation for sulfur dioxide dissolving in water to form acid rain - Correct Answers SO₂ + H₂O -> H₂SO₃  Describe the problems caused by acid rain - Correct Answers Acid rain damages plant life and life in lakes. It also corrodes limestone and some metals.  Write the chemical equation for the reaction between sodium and water - Correct Answers 2Na + 2H₂O -> 2NaOH + H₂  State 5 observations when potassium reacts with water - Correct Answers 1) fizzing occurs 2) potassium moves around 3) potassium melts 4) lilac flame is seen 5) potassium disappears 6) potassium floats  Complete the equation for the reaction by inserting the state symbols: 2Li(....) + 2H₂O(....) -> 2LiOH(...) + H₂(....) - Correct Answers 2Li(s) + 2H₂O(l) -> 2LiOH(as) + H₂(g)  State 4 observations when sodium reacts with water - Correct Answers 1) fizzing occurs 2) sodium moves around 3) sodium melts 4) sodium disappears 5) sodium floats  How should group 1 elements be stored - Correct Answers Under oil  Describe the relative reactivity’s of the elements in Group 1 - Correct Answers The reactivity increases as you go down the group, e.g. Li<Na<K<Rib  State the names of the gases present in air and their % by volume - Correct Answers nitrogen = 78%. Oxygen = 21%. Argon = 0.96%. carbon dioxide = 0.04%  Balance the following equation: WO₃ + H₂ -> W + H₂O - Correct Answers WO₃ + 3H₂ -> W + 3H₂O  Balance the equation for the reaction: ___ Hall(as) + ___ MN₂(s) -> ___Mancal₂(as) + ___H₂O(l) + ___ Cl₂(g) - Correct Answers 4 Hall(as) + MN₂(s) -> Mancal₂(as) + 2H₂O(l) + Cl₂(g)  Describe the formation of a covalent bond - Correct Answers The sharing of a pair of electrons between two nuclei  Give the definition of a covalent bond - Correct Answers Strong attraction between a shared pair of electrons and two nuclei  Explain the term covalent bond - Correct Answers Strong attraction between a shared pair of electrons and two nuclei  Draw a dot and cross diagram to show the covalent bonding in a molecule of hydrogen, H₂ - Correct Answers  Draw a dot and cross diagram to show the covalent bonding in a molecule of chlorine, Cl₂ - Correct Answers  Draw a dot and cross diagram to show the covalent bonding in a molecule of hydrogen chloride, Hall - Correct Answers  Draw a dot and cross diagram to show the covalent bonding in a molecule of water, H₂O - Correct Answers  Draw a dot and cross diagram to show the covalent bonding in a molecule of carbon dioxide, CO₂ - Correct Answers  Draw a dot and cross diagram to show the covalent bonding in a molecule of methane, CH₄ - Correct Answers  Draw a dot and cross diagram to show the covalent bonding in a molecule of ammonia, NH₃ - Correct Answers  Draw a dot and cross diagram to show the covalent bonding in a molecule of oxygen, O₂ - Correct Answers  Draw a dot and cross diagram to show the covalent bonding in a molecule of nitrogen, N₂ - Correct Answers  Draw a dot and cross diagram to show the covalent bonding in a molecule of ethane, C₂H₆ - Correct Answers  Draw a dot and cross diagram to show the covalent bonding in a molecule of ethane, C₂H4 - Correct Answers  If a substance has a simple molecular structure, what physical state might it be at room temperature? - Correct Answers Gas or liquid (low melting point)  Explain why nitrogen gas, N₂, is a gas at room temperature - Correct Answers Nitrogen has a simple molecular structure with weak intermolecular forces that require little energy to overcome  Draw the arrangement of particles in a solid, liquid and gas - Correct Answers What does this represent?  Describe the arrangement, movement and energy of the particles in a solid - Correct Answers Particles are close together and regularly packed. Energy is low. The particles vibrate around a fixed point.  Describe the arrangement and movement of the particles in a liquid - Correct Answers Particles are close together but irregular. The particles are free to move.  Describe the arrangement, movement and energy of the particles in a gas - Correct Answers Particles are far apart and there are no forces between them. Energy is high. The particles move quickly and freely.  Draw 3 particle diagrams to show the arrangement of particles in a solid, liquid and gas. Draw arrows between them and label boiling, condensing and freezing - Correct Answers X=boiling, Y=condensing, Z=freezing  Describe the changes in arrangement, movement and energy of particles when a liquid cools to become a solid - Correct Answers Arrangement becomes more regular. Particles vibrates in a fixed position. Particles lose energy  Describe the changes in arrangement, movement and energy of particles when a liquid turns into a solid - Correct Answers The particles form a regular arrangement, they slow down and lose kinetic energy  What name is given to the movement of gases? - Correct Answers Diffusion  State and explain how increasing temperature affects the diffusion of a gas - Correct Answers Gas diffuses quicker because particles have more energy.  Gas particles move at a speed of several hundred meters per second at room temperature. Explain why gases take several minutes to diffuse across a room - Correct Answers Gas particles collide with air particles and move in random directions  State the observation in the reaction between Hall(g) and NH₃(g) - Correct Answers White solid formed  Write a chemical equation for the reaction between hydrogen chloride and ammonia - Correct Answers Hall + NH₃ -> NH₄Cl  How many different elements are there in Be (OH) ₂? - Correct Answers 3  What is meant by the term element? - Correct Answers An element is a substance made of only one type of atom  What is meant by the term compound? - Correct Answers A compound is a substance that contains two or more elements chemically joined together