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Description
Flashcards by Jake Turner Retros, updated more than 1 year ago
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Created by Jake Turner Retros
over 8 years ago
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| Question | Answer |
| Topic 1 Qualitative analysis | Topic 1 Qualitative analysis |
| What are the two analysis? | Qualitative or Quantitative |
| Explain why the test for any ion must be unique | It wouldn't be useful if you didn't get a unique result for each ion, as you wouldn't be able to analyse a compound and then say it could be this or something else. |
| Describe tests to show the presence of the following ions in solids or solutions as appropriate: Al3+, Ca2+, Cu2+, Fe2+, Fe3+ using sodium hydroxide solution | Add a few drops of sodium hydroxide solution to a solution of your mystery compound. This should form an insoluble hydroxide. If you get a coloured insoluble hydroxide you can tell which metal was in the compound: Aluminium, Al3+ - White at first. But then redissolves in excess of NaOH to form a colourless solution Calcium, Ca2+ - White precipitate is formed. Copper, Cu2+ - Blue precipitate is formed. Iron(II), Fe2+ - Green precipitate is formed. Iron(III), Fe3+ - Brown precipitate is formed. |
| Describe tests to show the presence of Ammonium, NH4+? | Add sodium hydroxide to the solution and no precipitate will be formed however when heating it gives off ammonia. You can identify ammonia using damp red litmus paper turning it blue as well as it will smell like cat wee. |
| Describe tests to show the presence of the following ions in solids or solutions as appropriate: Cl-, Br-, I- using dilute nitric acid and silver nitrate solution? | Add dilute nitric acid followed by silver nitrate solution. 1) A chloride (Cl-) gives a white precipitate of silver chloride. 2) A bromide (Br-) gives a cream precipitate of silver bromide. 3) An iodide (I-) gives a yellow precipitate of silver iodide. |
| What do the tests of ions form the basis of what for testing by chemists? | 1) Working in the water industry to check the purity of drinking water. 2) For the presence of substances in blood. |
| Topic 2 Quantitative analysis | Topic 2 Quantitative analysis |
| What does dissolved calcium or magnesium ions in tap water lead to? | It makes the water hard. |
| What are the problems caused by hard water? | 1) Hard water won't easily form a lather with soap. It reacts with soap to make a nasty precipitate called scum instead. 2) To get a decent lather you need to use more soap - so lots of soap is wasted. |
| What are the two types of hard water? | Temporary and permanent |
| How can temporary hardness be removed by? | Temporary hardness can be removed by boiling. The calcium hydrogencarbonate decomposes to form insoluble calcium carbonate. This won't work for permanent hardness because heating a sulfate ion does nothing. |
| How can permanent hardness be removed by? | Permanent hardness as well as temporary hardness can both be removed by ion exchange resin. The resin contains lots of sodium ions (or hydrogen ions) and exchanges them for calcium or magnesium ions in the water that runs through them. |
| How do you find out how much of a substance is dissolved in water? | 1) Weigh a clean, dry evaporating basin. Weigh out 10g of sultion and put it in the basin. 2) Gently heat the basin to evaporate the water from the solution. 3) When all the water seems to have evaporated. Weigh the dry evaporating basin and remaining solid again. Reheat and Reweigh the evaporating basin and contents until there's no further change in its mass and then you will know that all the water has been evaporated. |
| What is the amount of a substance measured in? | Grams |
| What is the number of particles measured in? | Moles |
| How do you make a soluble salt using an acid and an insoluble reactant? | 1) You can make soluble salts by reacting an acid with an insoluble base, e.g. a metal carbonate or metal oxide. 2) You add the base to the acid - the solid will dissolve in the acid as it reacts. You will know when all the acid has been neutralised because the excess solid will just sink to the bottom of the flask. 3) Then filter out the excess solid to get a solution containing only salt and water. 4) Finally, heat it gently to slowly evaporate off the water and crystallise the salt. |
| How do you make a soluble salt using an acid and a soluble reactant? | 1) Soluble salts can be made by reacting an acid with an alkali, like sodium, potassium or ammonium hydroxides. 2) Add exactly the right amount of alkali to neutralise the acid. So, you must first carry out a titration to work out the exact amount of alkali needed. 4) The solution that remains when the reaction is complete contains only salt and water. Evaporate off the water slowly and you'll be left with a pure, dry salt. |
| What is an acid-base titration? | An acid-base titration is a neutralisation reaction where hydrogen ions (H+) from an acid react with hydroxide ions (OH-) from a soluble base (alkali). |
| What is the ionic equation for neutralisation? | H+(aq) + OH-(aq) --> H20(L) |
| Describe how to carry out simple acid-base titrations using burette, pipette and suitable acid-base indicators? | 1) Using a pipette and pippete filter, add some alkali to a conical flaskm along with two or three drops of indicator. 2) The indicator used depends on the strengths of the acid and alkali. 3) Fill a burette with the acid. Make sure you do this below eye level. 4) Using the burette, add the acid to the alkali a bit at a time - giving the conical flash a regular swirl. 5) The indicator changes colour when all the alkali has been neutralised, e.g. phenolphthalein is pink in alkalis, but colourless in acids. Record the volume of acid used to neutralise the alkali. 6) It's best to carry out a rough first titration. Then repeat this process at least two more times adding the acid slowly and carefully when you know you're close to the right volume. 7) If you get the same answer each time, then you know your results are reliable. |
| Topic 3 Electrolytic processes | Topic 3 Electrolytic processes |
| What are electrolytes? | Electrolytes are ionic substances in the molten state or dissolved in water. |
| Describe the movement of ions during electrolysis? | 1) The positively charged cations migrate to the negatively charged cathode. 2) The negatively charged anions migrate to the positively charged anode. |
| What is oxidation? | Loss of electrons. |
| What is reduction? | Gain of electrons |
| Where does reduction and oxidation occur in electrolysis reactions? | Reduction occurs at the cathode and the oxidation occurs at the anode in electrolysis reactions. |
| Describe the manufacture of sodium by the electrolysis of molten sodium chloride? | Sodium is not produced in the electrolysis of sea water as it is too reactive. It can be produced when molten sodium chloride is electrolysed. The products formed during this electrolysis are sodium metal and chlorine gas. |
| What can sodium be used in? | Sodium can be used in street lamps and as a coolant in some nuclear reactors. |
| What is the electrolysis of sodium chloride solution? | If an electric current passed through the sodium chloride solution, hydrogen gas would form at the negative electrode (cathode) and chlorine gas would form at the positive electrode (anode. A solution of sodium hydroxide would form. |
| Explain the formation of the products in the electrolysis of sodium chloride solution? | 1) At the cathode, two hydrogen ions accept one electron each to become one hydrogen molecule. 2) NaOH is left in the solution. 3) At the anode, two chloride ions lose one electron each and become one chlorine molecule. |
| Explain the formation of the products in the electrolysis of copper chloride solution? | Product at cathode: Copper(s) Product at anode: Chlroine(g) |
| Explain the formation of the products in the electrolysis of copper sulfate solution? | Product at cathode: Copper(s) Product at anode: Oxygen(g) |
| Explain the formation of the products in the electrolysis of sodium sulfate solution? | Product at cathode: Hydrogen(g) Product at anode: Oxygen(g) |
| Explain the formation of the products in the electrolysis of molten lead bromide? | 1) Lead bromide is electrolysed in the same way (except molten lead bromide is the electrolyte). 2)The half life equation for the reaction is Cathode: Pb2+ + 2e- -> Pb Anode: 2Br- --> Br2 + 2e- 3) The product of the electrolysis at the cathode is lead(L) and at the anode is bromine(g). |
| Describe the purification of copper by electrolysis using a pure copper cathode and an impure copper anode? | 1) The cathode starts as a thin piece of pure copper and more pure copper adds to it. 2) The anode is just a big lump of impure copper, which will dissolve. |
| Explain how electroplating can be used? | Decoration: 1) Electroplating can be used for jewellery and decorative items are also often electroplated with metals like gold or silver. 2) This improves the appearance of the metals - making them look shiny and attractive Prevention of Corrosion: 1) Some metals corrode, e.g. iron rusts. 2) Household objects like cultery and cooking utensils are electroplated with metals to stop them corroding. 3) The metals used for protection are unreactive and don't corrode easily. |
| Topic 4 Gases, equilibria and ammonia | Topic 4 Gases, equilibria and ammonia |
| What does one mole of any gas occupy at room temperature and atmospheric pressure? | 24 dm3 and is also known as the molar volume of the gas. |
| What are nitrogenous fertilisers manufactured from? | Ammonia and that they promote growth. |
| What are the environmental consequences of the over-use of fertilisers? | 1) Fertilisers stimulate the excessive growth of a layer of algae on the surface of the water. 2) Plants living below the surface die because the layer of algae blocks the light - they can no longer photosynthesise. 3) Decomposers feed on dead plants. They use up all the oxygen in the water, causing the fish to die. |
| Are chemical reactions reversible, true or false? | True |
| Does the Haber process use a reversible reaction? | Yes, the Haber process uses a reversible reaction between nitrogen (extracted from the air) and hydrogen (obtained from natural gas) to form ammonia. |
| What does dynamic equilibrium mean? | The reactions are still taking place in both directions, but the overall effect is nothing because the forward reaction and reverse reactions cancel each other out. The reactions are taking place at exactly the same rate in both directions. |
| Explain how the position of a dynamic equilibrium is affected? | Temperature 1) If you raise the temperature, the endothermic reaction will be favoured to use up the extra heat. 2) If you reduce the temperature, the exothermic reaction will be favoured to give out more heat. Pressure 1) If you raise the pressure, it will favour the reaction which produces less volume. 2) If you lower the pressure, it will favour the reaction which produces more volume. |
| What is the consequence of the change of position in the equilibrium and what will be needed to fix the problem? | It will result in less product and it is best to use a catalyst as a catalyst speeds up both the forward and backward reactions by the same out, making the reaction reach the equilibrium quicker. |
| Describe how, in industrial reactions such as the Haber process, the temperature, pressure and catalyst used produce an acceptable yield in an acceptable time for the industrial manufacture of ammonia?? | 1) The conditions used in the industrial manufacture of ammonia are that the pressure is 200 atmospheres, the temperature is 450 degrees and the catalyst used is iron. 2) Higher pressures favour the forward reaction since there are four molecules of gas on the left-hand side for every two molecules on the right. 3) So the pressure is set as high as possible to give the best percentage yield, without making the plant too expensive to build. Hence the 200 atmospheres operating pressure. 4) The forward reaction is exothermic, which means increasing the temperature will actually move the equilibrium the wrong way. 5) The trouble is, lower temperature means a slower rate of reaction. So they increase the temperature anyway, to get a much faster rate of reaction. 6) The 450 degrees is a compromise to get an acceptable yield in an acceptable time. It's better to wait just 20 seconds for a 10% yield than have to wait 60 seconds for a 20% yield. |
| Topic 5 Organic chemistry | Topic 5 Organic chemistry |
| How would you make a solution of ethanol by fermentation? | 1) Mix yeast and a solution of a carbohydrate in a clean container. Seal the container and leave it in a warm place. 2) Keep the mixture between 30 degrees and 40 degrees - fermentation happens fastest between these times. At lower temperatures, the reaction slows down. If it's too hit the enzyme in the yeast denatures. 3) It's important to keep the mixture in anaerobic conditions. Oxygen converts the ethanol to ethanoic acid. 4) When the concentration of alcohol reaches about 10 to 20%, the fermentation reaction stops, because the yeast gets killed off by the alcohol. 5) The yeast will fall to the bottom of the container - you can collect the solution of ethanol from the top. |
| Is it true that different percentages of ethanol are present in various drinks? | Yes |
| How can having too much alcohol be bad for the body? | 1) Ethanol affects the body. It generally makes people feel less inhibited which can help people to socialise and relax with each other. 2) However, ethanol reduces the activity of the nervous system. Getting drunk leads to increased reaction times, impaired judgement, poor balance and coordination, and unconsciousness. 3) Alcohol in excess also causes dehydration, which can cause damage brain cells. This can cause a noticeable drop in brain function and can lead to long-term memory loss. Too much drinking also causes severe damage to the liver, leading to liver disease. |
| How can having too much alcohol be bad for society? | 1) Getting drunk can lead to loutish behaviour and violence. It's linked to a lot of violent crime. 2) People can become addicted to alcohol, this is called alcoholism. It can lead to a family breakdown, and alcoholics sometimes end up losing their jobs and even becoming homeless. 3) Getting drunk can lead to irresponsible sexual behaviour. 4) Drink driving causes death and serious injury. 5) Excessive drinking has economic costs too. |
| How can ethanol be made, besides from fermentation? | It can be made by reacting ethene with steam. |
| Evaluate the factors which are relevant to the choice of method used in the manufacture of ethanol? | 1) Reacting ethene with steam to produce ethanol is a relatively cheap process, because ethene's fairly cheap and not much of it is wasted. 2) It's made in a large chemical plant, so it can be made coninously and quickly. The product is high quality and needs little further processing. 3) A reason for not reaction ethene with steam to produce ethanol is that ethene is produced from crude oil, which is a non-renewable resource and will start running out fairly soon. This mean using ethene to make ethanol will become very expensive. |
| What does the dehydration of ethanol result in? | The dehydration of ethanol results in the formation of ethene. |
| What is a homologous series? | 1) A homologous series is a group of compounds with the same general formula, this is a formula that describes all of the compounds in the group. The compounds in the series contain the same elements and have similar molecular structures. 2) As a result, all of the compounds in a homologous series have similar chemical properties and react in a similar way. 3) Their physical properties change gradually as the compounds increase in size. For example, the boiling points of compounds in a homologous series increase gradually with the size of the molecules. |
| Recall the names, formulae and structures of members of the following homologous series? | 1) Alkanes, up to 4 carbons atoms per molecule. 2) Alkenes, up to 3 carbons atoms per molecule. 3) Alcohols, up to 3 carbon atoms per molecule. 4) Carboxylic acids, up to 3 carbon atoms per molecule. |
| How does ethanoic acid form and where does the reaction occur in? | Ethanol is oxidised to form ethanoic acid and the reaction occurs in open bottles of wine and in the production of ethanoic acid in vinegar.. |
| What is the use of vinegar? | As a flavouring and as a preservative. |
| How is ethanoic acid a typical acid? | 1) It reacts just like any other acid with metals, bases and carbonates. 2) The salts formed with ethanoic acid are ethanoates. 3) Ethanoic acid is also a typical acid when it comes to its effects on indicators, for e.g. it will turn universal indicator orange/red and it will turn blue litmus paper red. |
| What does the reaction of ethanol with ethanoic acid produce? | An ester, ethyl ethanoate and water. |
| Write an equation for the reaction of ethanol with ethanoic acid using molecular and structural formulae? | |
| What are the uses of esters? | Esters are often used in flavourings and perfumes as they smell nice. |
| What are the uses of polyesters? | Polyesters are used in fabrics and plastics. The plastics can then be used to make bottles. |
| Polyesters can be recycled to form what? | Fleece that is used to make clothing. |
| Give two examples of esters? | Oils and fats |
| How are soaps made from esters and alkali? | 1) When an ester reacts with an alkali, you get soap. 2) Fats or oils are types of ester. These can be boiled up with concentrated alkali solution to make soap. 3) The oil or fats break down into glycerol and long-chain carboxylic acids, and the carboxylic acids then go on to react with the alkali. 4) So some soaps are just sodium or potassium salts of long-chain carboxylic acids. |
| How does a soap remove dirt or grease? | 1) In water, soap molecules form anions. Soap anions have a hydrophobic part and a hydrophillic part. 2) Hydrophobic means that it doesn't like water, but it's attracted to grease. This part of the molecule is normally a long hydrocarbon chain. 3) Hydrophillic means that it dissolves in water. This part of the molecule is normally small and ionic. 4) Soap anions let water and oil mix. The soap anions surround the oil and form droplets. This is how washing soap helps lift oily stains out of fabrics. |
| How are vegetable oils hydrogenated for the food industry? | 1) Unsaturated cells are less viscous than saturated cells. 2) Liquid unsaturated oils can be changed to soil saturated oils by breaking the double bonds and adding hydrogen. 3) A nickel catalyst is used to help the reaction along - the process is called catalytic hydrogenation. 4) The nickel catalyst is a solid and can be filtered out and used again. 5) As the filtered oil cools down to room temperature it turns into a solid fat. 6) Polyunsaturated vegetable oils are hydrogenated to make margarine. Not all the double bonds in the oil are hydrogenated, so some of the margarine is still unsaturated. It's firm enough to spread on your toast, but still low in saturates compared with butter. |
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