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44 Cards in this Set
- Front
- Back
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The conditions used for fermentation of carbohydates to form ethanol are..
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- add yeast (contains the enzyme zymase)
- temperature of35oC - anaerobic conditions |
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Write the balanced equation for the reaction of ethene with steam.
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C2H4 + H2O → C2H5OH
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Describe what is meant by an homologous series. |
- same general formula - same functional group - consecutive compoundsdiffer by CH2 - gradual variation in physicalproperties - similar / same chemical properties / reactions |
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State the type of reaction that occurs when ethanol changes into ethanoic acid. |
Oxidation. |
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Describe what you would see when a piece of magnesium ribbon is added todilute ethanoic acid. |
- effervescence/fizzing/bubbling - solid disappears - colourless solution Allowed - solid dissolves and magnesium floats of surface of the acid |
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Describe the test to show that a solution contains iodide ions. |
- add dilute nitric acid then silvernitrate solution - yellow precipitate |
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Describe the test to show that a solid contains ammonium ions. |
- add to sodium hydroxide solution and warm - test gases with damp/moist (red)litmus paper - litmus paper turns blue |
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When sodium hydroxide solution is added to a solution , a red-brownprecipitate is formed.This test shows that the ion present in the solid is. |
- iron(III), Fe3+ |
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Sodium hydroxide solution can be used to test for aluminium ions and for calciumions in solution. Describe the results of these tests for aluminium ions and for calcium ions,explaining how the results distinguish between the two ions. |
- white precipitate with calcium ions - white precipitate with aluminium - precipitate dissolvesin excess for aluminium ions/ precipitate remainsin excess for calcium ions note - 3rd mark dependent on firstand/or second mark beingawarded |
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What happens in hydrogenation of a liquid oil? |
- the liquid oil is changed intoa solid. - double bonds break to form single bonds |
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Which of the following would be a suitable alkali to use in the production of soaps? A) sodium chloride B) sodium hydroxide C) sodium nitrate D) sodium sulfate |
- sodium hydroxide |
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Explain how soap anions remove grease marks from clothes during washingwith water. |
- tail / (hydrophobic /hydrocarbon) end into grease - head / (anion / hydrophilic) end into water - allows grease to mix withwater when surrounded bysoap (anions) / grease issurrounded by soap - surface tension lowered |
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Give the name of the carboxylic acid that has three carbon atoms in each molecule. |
- propanoic acid |
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When ethanoic acid, CH3COOH, reacts with ethanol, C2H5OH, ethyl ethanoateis one of the products formed. Write the balanced equation for the reaction. |
CH3COOH + C2H5OH --> CH3COOC2H5 + H2O |
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Polyesters are used to make plastic bottles.
State another use of polyesters. |
- making fibres/fleece/clothing/fabrics/bedding/computer mousemats/yarns/ropes/safetybelts/filters/insulating tape/woodfinishes/plastic carrier bags
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Give the name of a suitable indicator to use in an acid-base titration.
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- methyl orange
- phenolphthalein - litmus |
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State the colour change for this indicator at the end point (acid in burette, base in conical flask). |
- methyl orange:yellow --> orange/pink/red - phenolphthalein:magenta/pink --> colourless - litmus: blue --> red |
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Some metal objects are electroplated to improve their appearance. Give another reason why some metal objects are electroplated. |
- improves resistance to corrosion |
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In an electrolysis experiment, oxide ions, O2–, form oxygen gas, O2. Write the balanced half equation for the reaction. |
2O(2-) -> O2 + 4e(-) |
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Sodium chloride is an ionic compound. It contains sodium ions, Na+, and chloride ions, Cl–. When molten sodium chloride is electrolysed, sodium metal and chlorine gas areformed. Describe how the sodium ions and chloride ions in solid sodium chloride areconverted into sodium and chlorine by electrolysis. (6 marker - first half - at cathode) |
- sodium chloride is melted and ions are free to move - {sodium / positive} ions move to cathode - (sodium) metal forms at cathode - sodium ions gain electrons ... - to form atoms - this is reduction - Na+ + e- --> Na |
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Sodium chloride is an ionic compound. It contains sodium ions, Na+, and chloride ions, Cl– . When molten sodium chloride is electrolysed, sodium metal and chlorine gas are formed. Describe how the sodium ions and chloride ions in solid sodium chloride are converted into sodium and chlorine by electrolysis. (6 marker - second half - at anode) |
at anode - chloride / negative ions move to anode - chlorine gas forms at anode - chloride ions lose electrons ... - to form atoms - this is oxidation - two chlorine atoms combine to form a chlorine molecule / share electrons - Cl- -> Cl + e- / 2Cl- -> Cl2 + 2e- - 2 Cl - Cl2 |
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Hydrogen reacts with oxygen to form water vapour. 2H2(g) + O2(g) -> 2H2O(g) If 200 cm3 of hydrogen react completely with 100 cm3 of oxygen, what is themaximum volume of water vapour formed, if all volumes are measured at thesame temperature and pressure? |
- 200 cm3 |
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What is the source of the hydrogen used in the Haber process? |
- natural gas |
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When nitrogen reacts with hydrogen, the amount of ammonia graduallyincreases until it becomes constant. N2(g) + 3H2(g) -> 2NH3(g) Explain why the amount of ammonia remains constant. |
- forward and back reactions takeplace / reversible / dynamic - at the same rate / equilibrium - dynamic equilibrium (gets you 2 marks) |
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Explain, with reasons, why the Haber process conditions are better for themanufacture of ammonia than 90 atm pressure and 300 °C, without acatalyst (6 marker - first 3rd - temperature). |
- higher temperature reaches equilibrium faster - because molecules move faster - therefore more frequent collisions - molecules have more energy - therefore more collisions have required energy - but yield will be lower - because higher temperature favours endothermic reaction - equilibrium shifts to left hand side - which is decomposition of ammonia / ammonia reformselements |
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Explain, with reasons, why the Haber process conditions are better for the manufacture of ammonia than 90 atm pressure and 300 °C, without a catalyst (6 marker - second 3rd - pressure). |
- higher pressure gives increased yield - equilibrium shifts to right hand side - because decrease in number of molecules going from left toright - therefore decrease in volume - favoured by increase in pressure - reaches equilibrium faster - because molecules closer together - so get more frequent collisions |
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Explain, with reasons, why the Haber process conditions are better for the manufacture of ammonia than 90 atm pressure and 300 °C, without a catalyst (6 marker - third 3rd - catalyst). |
- catalyst causes reaction to reach equilibrium faster /catalyst increases rates (of both forward and back reactions) - lowers the activation energy (of both forward and backreactions) - reaction follows a new pathway - does not affect yield - equilibrium position not affected |
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Which of these ions will be attracted to the cathode during the electrolysis ofsodium chloride solution? - sodium ions, Na+ - chloride ions, Cl– - hydrogen ions, H+ - hydroxide ions, OH– |
- H+ and Na+ ions |
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2Cl- → Cl2 + 2e Explain how the half-equation shows that chloride ions are oxidised. |
- electrons - have been lost/removed note: second mark conditional onfirst |
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Suggest why the solution remaining at the end of the electrolysis is alkaline. |
- it contains (excess) hydroxide/OH¯ ions
- sodium/Na+ ions and hydroxide/ OH¯ ionsremain - it is sodiumhydroxide/NaOH - hydrogen/H+ ions havebeen removed (at thecathode) note: allow no hydrogen ions left/acidicions removed |
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The electrolysis of sodium chloride solution does not produce metallic sodium. State what change you would make to the electrolyte to obtain metallic sodium. |
- use molten/liquid sodiumchloride /electrolyte / melt it/sodium chloride/electrolyte |
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When copper sulfate solution is electrolysed using inert electrodes, oxygen isformed at the positively charged anode. Explain how the oxygen is formed from ions in the solution. |
- hydroxide/OH- ions from water - ions lose electrons /areoxidised - Or two marks for half equation, even unbalanced,showing hydroxide ions losingelectrons |
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Ethanol, C2H5OH, can be converted into ethanoic acid, CH3COOH. In this reaction ethanol is ... |
- oxidised |
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Describe how ethanol can be produced from sugar by fermentation. |
- dissolve sugar in water/sugar solution - add yeast - warm/any temperature between 15 - 40 degrees celcuis - anaerobic/ no oxygen |
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A country has large amounts of available fertile land. It has no reserves of crude oil. It is not a wealthy country. Explain why this country produces the ethanol it needs by fermentation ratherthan from ethene. |
Mark 1, sugar , one from - sugar obtained from plants/crops/specific crop - plenty of land available to grow plants /crops/specific crop forfermentation Mark 2 - ethene obtained from crude oil /fractional distillation /cracking Mark 3, cost/energy, onefrom - cannot afford to buy crude oil - crude oil is too expensive - more expensive to use/buy/produce ethene - cheaper to use fermentation |
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Explain what is meant by a dynamic equilibrium |
Marking point 1 – one from - forward and back reactionstake place at the sametime - rate of the forward andback reactions is the same Marking point 2 – one from - no overall change in the amount/concentration/mass/ volume of each substance / reactant /product - no observable change |
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Explain how the use of a lower temperature would affect the equilibrium yieldof ammonia. |
- lower temperature favoursforward reaction/equilibriumshifts to the right
- because forward reactionis exothermic - yield increases |
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Even at 450°C, the reaction is very slow. State what is used in industry to overcome this problem. |
- catalyst. |
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Suggest why universal indicator must not be used in titration experiments. |
- no sharp/clear/distinct change in colour - gradual colour change - there are too many differentcolours |
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Describe a titration experiment to find the exact volume of hydrochloric acidneeded to neutralise 25.0 cm3 of sodium hydroxide solution and how you woulduse this result to obtain pure, dry crystals of sodium chloride (6 mark ,first half, titration). |
- rinse pipette with alkali and burette with acid - measure alkali using a pipette - into suitable container e.g. flask/beaker - add a few drops of indicator / suitable named indicator (egmethyl orange/phenolphthalein) - flask on a white tile - fill burette with acid - read level/volume (of acid) in burette - add acid from burette to the flask slowly / swirl the flask - until {indicator just changes colour/correct colour change fornamed indicator (eg methyl orange yellow to peach/orange,phenolphthalein pink to colourless)/solution is neutral} - read level/volume (of acid) in burette - repeat experiment - until concordant results |
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Describe a titration experiment to find the exact volume of hydrochloric acid needed to neutralise 25.0 cm3 of sodium hydroxide solution and how you would use this result to obtain pure, dry crystals of sodium chloride (6 mark , second half, salt preperation). |
- mix the same volume of alkali with the volume of aciddetermined from the first experiment but do not addindicator (or add (activated) charcoal to remove indicator,then filter) - pour solution into an evaporating basin - heat solution/leave the water to evaporate until pure saltcrystals are left |
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Aluminium ions, Al3+, react with hydroxide ions in solution to give a whiteprecipitate of aluminium hydroxide.
Write the ionic equation for this reaction. |
Al3+ + 3OH- → Al(OH)3 (3 marks)
- OH- - Al(OH)3 - balancing 3rd mark, conditional oncorrect formulae |
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A technician knew a colourless substance was one of potassium sulfate, potassium iodide, sodiumsulfate or sodium iodide. Explain how, using chemical tests, the technician could find out if the substanceleft in the beaker was potassium sulfate, potassium iodide, sodium sulfate orsodium iodide (6 marker - test for cation and sulphate ions). |
Test for cation - flame test - if the flame is yellow/not lilac, sodium ions are present - if the flame is lilac/not yellow, potassium ions arepresent Test for sulfate ions - make a solution of the crystals in water - add dilute hydrochloric/nitric acid - add barium chloride/nitrate solution - if there is a white precipitate, sulfate ions are present - if there is no precipitate, iodide ions are present - Ba2+ + SO42- → BaSO4 |
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A technician knew a colourless substance was one of potassium sulfate, potassium iodide, sodium sulfate or sodium iodide. Explain how, using chemical tests, the technician could find out if the substance left in the beaker was potassium sulfate, potassium iodide, sodium sulfate or sodium iodide (6 marker - test for cation and sulphate ions). |
Test for iodide ions - make a solution of the crystals in water - add dilute nitric acid - add silver nitrate solution - if there is a yellow precipitate, iodide ions are present - if there is no precipitate, sulfate ions are present - Ag+ + I¯ → AgI OR - make a solution of the crystals in water - add chlorine water - then cyclohexane - if the cyclohexane/top layer turns purple, iodide ionswere present - if there is no colour change, sulfate ions are present - Cl2 + 2I- → 2Cl- + I2 |
