Azonosító jel: KÉMIA ANGOL NYELVEN EMELT SZINTŰ ÍRÁSBELI VIZSGA május 12. 8:00. Az írásbeli vizsga időtartama: 240 perc

Transcription

1 ÉRETTSÉGI VIZSGA május 12. KÉMIA ANGOL NYELVEN EMELT SZINTŰ ÍRÁSBELI VIZSGA május 12. 8:00 Az írásbeli vizsga időtartama: 240 perc Pótlapok száma Tisztázati Piszkozati NEMZETI ERŐFORRÁS MINISZTÉRIUM Kémia angol nyelven emelt szint írásbeli vizsga 0802

2 Important informations The examination test should be solved within 240 minutes, after 240 minutes the work should be finished. The sequence of answering the questions is free. For the solution of the problems calculators without text-storage capability and fourplace logarithm tables can be used. Use of other electronic or written help is forbidden. Read the introductory text of the questions carefully and keep its instructions. Write the answers in ink. If you cancel an answer or part of an answer, the canceled work can not be evaluated. For the calculations, you can get maximum number of points only if the main steps of the calculation are indicated, too. Please, don t write anything into the gray squares. írásbeli vizsga / május 12.

3 1. Essay Read the following text carefully and answer the questions The chemistry of fire In Great Britain, every year about half a million fires are extinguished, the fire claims hundreds of human lifes and during the accidents, several thousand people are injured. What is fire? Fire is actually unregulated burning, it starts when an organic polymer reacts with oxygen under heat evolution. To every fire a combustible sustance, an oxidizing agent which is usually oxygen from the air and ignition are needed. During ignition and burning, complicated chemical and physical processes are taking place. Chemical processes While heating polymers above ºC, chemical bonds are broken and as primary products volatile substances of small molecular weight are produced. At higher temperatures depending on the polymer poisonous products such as hydrogen cyanide, nitriles, polyaromatic hydrocarbons can be liberated. These are mixed with oxygen on the surface of the fuel and burn away. Part of the primary products are decomposed in the flame: different oxydes of carbon and nitrogen, as well as water can be evolved. These substances can be released from the flame even before the end of the combustion process: for example dangeroous carbon monoxide is produced mainly during incomplete burning. Before fume formation, complicated chemical processes are taking place, too. In case of an inadequate air supply, more smoke is formed than in well ventilated buildings. Smoke is dangerous because it hinders normal visibility. Based on their biological effect, substances produced in fire can be classified in two groups. Substances influencing the central nervous system like carbon monixide and hydrogen cyanide are blocking the oxigen uptake of blood and hindering this way the oxygen supply of cells. The other group of substances having a biological effect is made up by substances irritating sense and respiratory organs (for example aldehydes and inorganic compounds). The listed substances are hindering people to escape fire. More than half ot lethal accidents are caused by poisonous gases. Growing flames Fire reaching a horizontal surface like a ceiling or a roof, is forced to spread along the surface. Air is supplied only from beneath and therefore, flames can grow up to a quintuple size. Heat irradiated downwards and hot particles streaming downards are also facilitating the spreading of fire. Small fires which seem to be under control without any danger, can turn into deathtraps in secons if flames are spreading under the ceiling and ignite fresh material. Fire fighting Two hundred years ago water was the most important substance to extinguish fire. Nowdays, different chemicals, for example wetting agents, foams, halogenized hydrocarbons (halons), hydrogen carbonates and inert gases are used for this purpose, too. írásbeli vizsga / május 12.

4 Burning surfaces are cooled down even today by water. Fire is spreading upwards while water tends to get downwards because of gravitation. Wetting agents facilitate the movement of water and foams are used to control the way of water. During the decomposition of polymers, very reactive free radicals are formed which catalyze the occurring reactions and accelerate burning. Halons are absorbing free radicals and damp flames. However, they are environmental pollutants and therefore, new substances are searched to substitute them. During the decomposition of the salts, especially hydrogen carbonates of alkali metals, carbon dioxide is formed which covers the fuel as a blanket and starves the fire from oxygen. In other cases, the surface of the fuel is covered by foams from the outer world to suppress the escape of the vapors of fuel and the supply of oxygen. From time to time, oxygen from the air feeding the fire is diluted by inert gases. After Kathryn Roberts, InfoChem, Education in Chemistry a) Classify substances produced in fire based on their biological effect. b) Draw the structural formula of one of the substances influencing the central nervous system, mentioned in the text. Indicate bonding and non-bonding electron pairs, as well. c) What is the role of alkali hydrogen carbonates in fire fighting? írásbeli vizsga / május 12.

5 d) Write balanced reaction equation of the thermal decomposition of sodium hydrogen carbonate. e) What is the role of organic halogen derivatives in fire fighting? Explain, why is their use strongly decreasing in the last years. 8 points írásbeli vizsga / május 12.

6 2. Analytical question Examination of aqueous solutions of salts The following salts are studied: A) sodium sulfate B) potassium carbonate C) ammonium nitrate a) Write the chemical formulae of these salts. b) Which salt can be originated from the reaction of a strong acid with a strong base? Write the chemical formulae of the respective acid and base. Write balanced reaction equation of the process, too. c) Which salt is basic in an aqueous solution? Explain the basicity by writing ionic equation of the occurring process. d) Chose one of the above listed salts which is forming a precipitate by the addition of calcium chloride solution. Write balanced equation of the reaction. írásbeli vizsga / május 12.

7 e) The following data are given. The lattice energy of ammonium nitrate is -367 kj/mol, the hydration energy of ammonium ions is -133 kj/mol and that of nitrate ions is -207 kj/mol. Using these data, calculate the heat of dissolution of ammonium nitrate. f) How does the temperature of the solution change when ammonium nitrate is dissolved in water? g) Based on the above data, state how the solubility of ammonium nitrate is changing by increasing the temperature. Explain your answer. h) What happens if the aqueous solution of sodium sulphate is electrolyzed between indifferent (for example graphite or platinum) electrodes for a longer time applying direct current? Write the reaction equation of the processes occurring at the cathode and the anode. 15 points írásbeli vizsga / május 12.

8 3. Four types of assotiation Write the correct letter mark in the corresponding empty cells of the table at the end of the question. A) Methanol B) Propan-2-ol C) Both of them D) None of them 1. In the solid state it has a molecular lattice structure. 2. Even in small amounts, it can cause blindness, it is a lethally poisonous compound. 3. At 25 ºC and standard pressure it is found in the gasous state. 4. In its molecule, there are as many carbon atoms as in that of acetone. 5. It is contained in large quantities in commercial alcoholic beverages. 6. The product of its mild oxidation gives a positive silver mirror test. 7. Its reaction with copper(ii) oxide results acetaldehyde. 8. It reacts with sodium hydroxide under hydrogen evolution. 9. By elimination of water, an alkene can be prepared from it. 10. It is also called wood alcohol. 11. Its aqueous solution is acidic points írásbeli vizsga / május 12.

9 4. Simple choice Write the only correct letter mark into the empty cell on the right-hand side of the answers. 1. Which line contains only gases which have a density smaller than 1, relative to oxygen gas in the same state? A) Methane, ethyne, propene. B) Formaldehyde, ethane, dimethyl ether. C) Methane, ethene, carbon monoxide. D) Butadiene, propyne, acetylene. E) Methylamine, propane, cyclopropane. 2. In which processes can the evolving gas be collected under water? a) The reaction of copper and nitric acid. b) The reaction of calcium carbide and water. c) The reaction of table salt and concentrated sulfuric acid. d) The raction of ethanol and concentrated sulfuric acid (above 160 ºC, dropping them onto quartz sand). e) The reaction of aluminium and sodium hydroxide solution. A) a, b, e B) b, c, d C) b, d, e D) a, d, e E) c, d, e 3. Which of the following salts is colourless in an aqueous solution? A) KMnO 4 B) Cu(NO 3 ) 2 C) Fe 2 (SO 4 ) 3 D) KHCO 3 E) NiCl 2 4. Which of the following statements is not true for magnesium? A) Ignited in air, it is burnt in a heavy reaction with a brilliant flame. B) Heating its carbonate, the remainder is a white powder. C) It does not evolve a gas from sodium hydroxide solution. D) In its reaction with hydrochloric acid a pungent, yellowish-green gas is evolved. E) It belongs to the light metals. írásbeli vizsga / május 12.

10 5. Which of the following gases is colourless and odourless? A) Hydrogen sulfide. B) Methane. C) Nitrogen dioxide. D) Chlorine. E) Formaldehyde. 6. Which line contains exclusively spherically linear particles? A) SO 2, CH 4, HCN B) SO 3, C 2 H 2, H 2 S C) C 2 H 2, CO 2, HCN D) C 2 H 6, H 2 O, CO 2 E) CO 2-3, CS 2, HCHO 7. Which line contains exclusively dipole molecules? A) H 2 O, NH 3, CH 4 B) NF 3, CO 2, H 2 S C) H 2 O, SO 2, H 2 S D) C 2 H 2, H 2 SO 4, HI E) SO 3, CS 2, PH 3 7 points 5. Analytical question and calculation problem During the industrial and laboratory preparation of metals, in several cases gaseous reducing agents are applied. The following questions are referred to such gases. At the solution of the problem, waste losses can be neglected. Δ f H(CH 4 ) = kj/mol; Δ f H(CO) = -111 kj/mol; Δ f H(CO 2 ) = -394 kj/mol; Δ f H (H 2 O(g)) = -242 kj/mol, M(air) = 29.0 g/mol a) It is one of the most frequently used gases, it is in the elemental state, it is colourless and odourless, its density is 14.5 times smaller than that of the air under the same conditions. In its reaction with metal oxides, water is formed as a by-product. Write the structural formula of a molecule of the gas. írásbeli vizsga / május 12.

11 b) In course of the industrial preparation of wolfram, wolfram(vi) oxide is reduced by the gas described in paragraph a). Write balanced reaction equation of the process. c) The mostly known field of application of another industrial gas is the metallurgy of iron. This gas is formed in an equilibrium process in the reaction of carbon dioxide and hot coke. Name the compound. Write the reaction equation of the formation of the gas. d) Write the reaction equation of the reduction of iron(iii) oxide using the gas described in paragraph c). írásbeli vizsga / május 12.

12 e) The mixture of the gases described in paragraphs a) and c) is also used in the organic chemical industry for the preparation of different products. What is the name of this gas mixture? Write balanced equation of the reaction of methane and steam which is used to prepare the mentioned gas mixture. f) Calculate the heat of reaction of the processes described in questions c) and e). 12 points írásbeli vizsga / május 12.

13 6. Calculation problem 3.00 g of a pulverized mixture contains 27.0 mass % magnesium carbonate beside elemental magnesium. The mixture is dissolved in a 31.0 mass % sulfuric acid of a density of 1.23 g/cm 3 in a stoiciometric ratio. a) Write the reaction equation of the occurring processes. b) What volume of gas was evolved in the process at 25.0 ºC and standard pressure? c) Give the average molar mass of the evolved gas. d) What volume of sulfuric acid was used to dissolve the pulverized mixture? 13 points írásbeli vizsga / május 12.

14 7. Calculation problem A liquid-state, two-component mixture is composed of organic compounds containing four carbon atoms (compounds A and B). Compounds A and B are constitutional isomers of each other grams of the liquid mixture are completely burned. The hot product of the combustion is bubbled first through a gas washer containing concentrated sulfuric acid and then through another gas washer containing concentrated potassium hydroxide solution. In the first gas washer, we observe 18.0 g and in the second one 35.2 g increase of mass. The same amount of the liquid mixture reacting with sodium liberates 1.96 dm 3 gas at 25 ºC temperature and standard pressure. a) Calculate the number of moles of water and carbon dioxide produced at the complete burning of the liquid mixture of the given mass. b) Determine the chemical formula of the organic compounds present in the liquid mixture by calculation. írásbeli vizsga / május 12.

15 c) Write a possible constitutional formula of A and B, respectively containing different functional groups. d) Give the composition of the liquid mixture in mol percent. 16 points írásbeli vizsga / május 12.

16 8. Calculation problem and analytical question Methylamine is a colourless, water-soluble gas having an unpleasant odour similar to that of ammonia. a) Give the structural formula of the molecule indicating bonding and non-bonding electron pairs. b) How can you explain its solubility in water, based on the structure of the substance. c) How does the equilibrium concentration of methylamine molecules change when adding solid sodium hydroxide to the aqueous solution of methylamine? Explain the change by writing reaction equation of the occurring process, too. írásbeli vizsga / május 12.

17 d) The ph value of an aqueous mol/dm 3 methylamine solution is Calculate the basic dissotiation constant of methylamine. e) In what ratio do you have to dilute the solution of ph 11.0, to get a solution of ph 10.0? 16 points írásbeli vizsga / május 12.

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20 Attention, please! It should be filled by the evaluating teacher. maximum points 1. Essay 8 2. Analytical question Four types of assotiation Simple choice 7 5. Analytical question and calculation problem Calculation problem Calculation problem Calculation problem and analytical question 16 Correct use of notations and units 1 For calculations, if the results have a precision corresponding to that of the given 1 data Points of the written exam 100 reached points marking teacher Date:... Feladatsor Test elért pontszám egész számra kerekítve/ reached points rounded to whole number programba beírt egész pontszám/ whole points written in the program javító tanár/marking teacher jegyző/ underwriter Dátum/Date:... Dátum/Date:... írásbeli vizsga / május 12.