11. Group 17
A section of Chemistry, 9701
Listing 10 of 617 questions
Allyl chloride is an important chemical used in the manufacture of plastics, pharmaceuticals and pesticides. Cl allyl chloride Give the systematic name of allyl chloride. Allyl chloride can be produced by many different methods. The most common method is chlorination of propene which proceeds via a free-radical substitution mechanism. Cl Cl 2 The initiation step in this reaction is the formation of chlorine radicals (Cl ●) from Cl 2 molecules. State the conditions required to initiate this reaction. The propenyl radical, CH2=CHCH2 ●, is formed in the first propagation step of the reaction. Write an equation to show the formation of CH2=CHCH2 ● in this propagation step. Explain why the free-radical substitution reaction gives a low yield of allyl chloride. Allyl chloride can also be formed by the following substitution reaction. Cl OH reagent X Suggest the identity of reagent X. A series of reactions starting from allyl chloride is shown. Cl Cl HO reaction 1 HCN and NaCN reaction 3 reaction 2 OH Cl CH3COO CH3COO CN CH3COO CH3COO Y Suggest a reagent that can be used in reaction1. In reaction2, the organic product of reaction1 is mixed with concentrated H2SO4 and an organic acid, and then heated under reflux. State the role of the concentrated H2SO4. Identify the organic acid used. role of the concentrated H2SO4 identity of the organic acid  State the name of the mechanism that occurs in reaction3. The organic product of reaction3 is Y. Y can be hydrolysed using excess aqueous H2SO4 to form Z. The molecular formula of Z is C4H8O4. Draw the structure of Z.  2-bromo-1-chloropropane, CH3CHBrCH2Cl, is the major product of the reaction of allyl chloride with HBr. Cl Cl HBr and Br major product Cl Br minor product Explain why 2-bromo-1-chloropropane is the major product of this reaction. 
9701_m19_qp_22
THEORY
2019
Paper 2, Variant 2
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State the electronic configuration of the iron atom. Apart from its electronic structure, state two properties of iron or its compounds that are characteristic of a transition element. Acidified solutions of iron(salts can be titrated using a dilute solution of potassium manganate(, KMnO4. Use the Data Booklet to calculate the standard cell potential and to write a balanced ionic equation for the reaction that takes place during the titration. Explain why no indicator is required for this titration. What colour change would you see at the end point? Use the reaction between Fe3+ ions and water molecules to explain the meanings of the terms ligand and complex formation. Use An important biological molecule containing iron is haemoglobin. What is the role of haemoglobin in the body? Use your answer to to explain why carbon monoxide is poisonous. In a possible industrial synthesis of ethanol, the complex Fe(CO)5 catalyses the reaction between carbon monoxide, hydrogen and methanol according to the following equation. 200 °C CH3OH + 2CO + H2 –––––→CH3CH2OH + CO2 300 atm Describe a test (reagents and observations) that would distinguish ethanol from methanol. reagents observation with methanol observation with ethanol Examiner's Use
9701_s05_qp_4
THEORY
2005
Paper 4, Variant 0
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A large number of organic compounds are soluble in both water and non-aqueous solvents such as hexane. If such a compound is shaken with a mixture of water and the non-aqueous solvent, it will dissolve in both solvents depending on the solubility in each. State what is meant by the term partition coefficient. When 100 cm3 of an aqueous solution containing 0.50 g of an organic compound X was shaken with 20 cm3 of hexane, it was found that 0.40 g of X was extracted into the hexane. Calculate the partition coefficient of X between hexane and water. If two 10 cm3 portions of hexane were used instead of a single 20 cm3 portion, calculate the total amount of X extracted and compare this with the amount extracted using one 20 cm3 portion. PCBs are highly toxic compounds released into the atmosphere when some plastics are burned at insufficiently high temperatures. In recent years PCB residues have been found in the breast milk of Inuit mothers in northern Canada. Foods, such as oily fish, seal and whale meat, which are high in fat, form an important part of the Inuit diet. Suggest why berries and drinking water are not contaminated by PCBs in the same way that oily fish, seal and whale meat are. Based on the information provided, what can you say about the partition coefficient between fat and water for PCB residues? The diagram shows the result of two-way paper chromatography. X starting point solvent 1 solvent How many spots were there after the first solvent had been used? Circle the spot that moved very little in solvent 2, but moved a greater distance in solvent 1. Draw a square around the spot that could be separated from the rest by using only solvent 1.
9701_s09_qp_4
THEORY
2009
Paper 4, Variant 0
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Use Potassium manganate(can be used to estimate the percentage of hydrogen peroxide in household bleach. The following unbalanced equation represents the reaction between them. MnO– 4 + H2O2 + H+ Mn2+ + H2O + O2 Balance this equation by putting the appropriate numbers in the spaces above. Use data from the Data Booklet to calculate the E o cell for the reaction. When 0.020 mol dm–3 KMnO4was added from a burette into an acidified 25.0 cm3 sample of H2O2, 15.0 cm3 of KMnO4 was required to reach the end-point. Describe what you would see during this titration, and also at the end-point. Calculate the concentration of H2O2 in the sample.
9701_w07_qp_4
THEORY
2007
Paper 4, Variant 0
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Use 10 Read the following article about the use of bacteria in mining, and then answer the questions that follow it. The discovery that bacteria could ʻmineʼ metals for us was made in Spain. The Rio Tinto mine, in the southwest corner of Spain, was originally mined for copper by the Romans some 2,000 years ago. In 1752, some mining engineers looked over the mine to see if it could possibly be re-opened. They noticed streams of a blue-green liquid running from spoil heaps of the processed rock that lay around the mine. When this blue-green liquid ran over iron, it coated the iron with a brown film. The brown film was metallic copper. There was still some copper left in the spoil heaps. At the time, everybody thought that the copper was being dissolved in the liquid through a simple chemical reaction. But in 1947, US scientists discovered that the copper was being ʻminedʼ by a bacterium called Thiobacillus ferrooxidans. The bacterium Thiobacillus ferrooxidans lives off the chemical energy trapped in metal sulphides. In the ore, the copper exists as copper sulphide. The bacteria gain energy by converting the copper sulphide to copper sulphate, which is then excreted. At the same time, they absorb the difference in energy in the chemical bonds. These bacteria can also obtain energy in similar reactions with ores of zinc, lead and uranium. Use the Data Booklet to explain why the blue-green liquid coated the iron with copper. Write an equation for the reaction. Suggest two reasons why this method of extracting copper might be useful for ore containing only a small percentage of copper. Suggest one disadvantage of using bacteria rather than traditional mining and smelting methods. Examiner’s Use In conventional copper mining, the ore will typically contain 0.5 – 2.0% copper, which gives an idea of what a valuable resource copper is. The ore from a particular mine contains 0.75% copper, and 150 000 tonnes of ore are mined each year. From this ore about 60% of the copper is extracted, and the remainder is left in the ‘spoil heaps’ of processed ore. What mass of copper is extracted each year? If the use of bacteria can recover a further 17% of copper from the spoil heaps, what is the extra mass of copper produced? Suggest why bacteria are unlikely to be used in the extraction of aluminium. Metals like copper and zinc from abandoned mines can contaminate ground-water. Suggest one way of removing these contaminants.
9701_w07_qp_4
THEORY
2007
Paper 4, Variant 0
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11 One of the greatest challenges facing scientists today is the development of effective drugs to treat different forms of cancer. Drugs can be introduced into the body by injection or by mouth. Taking drugs by injection avoids the drug being broken down in the digestive system. State two other advantages of giving drugs by injection. The drug Ultiva has been developed to treat ovarian cancer, and is usually given by injection. H3C OCH3 OCH3 O O O N N Ultiva Study the structure of Ultiva and draw a circle around two different functional groups that could be broken down in the digestive system. One way of avoiding the breakdown of drugs in the body is to use a specially designed nanoparticle which encloses the drug. If the nanoparticles are made of a particular sort of polymer, they absorb water at the slightly acidic pH inside some cells, increasing their diameter from around 100 nm to around 1000 nm. This spreads out the polymer chains allowing release of the drug. Other than absorbing water, suggest a property this polymer would need to possess for its use in drug delivery. Why would this method of release not work if the nanoparticles were taken by mouth? Polymers may be formed by two different types of chemical reaction. Name the two types of reaction and write an equation to illustrate each reaction type. name equation name equation The breakdown of polymers, such as carbohydrates and proteins in the body is important for digestion. What type of reaction is generally involved?
9701_w10_qp_43
THEORY
2010
Paper 4, Variant 3
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Questions Discovered
617