Cq Fertilizers And Gas Volume

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Fertilizers and Gas Volume : 1986 2. (b) Sodium hydrogencarbonate decomposes upon heating to give carbon dioxide. What volume of carbon dioxide at room temperature and atmospheric pressure can be obtained by decomposing 1.00 g of sodium hydrogencarbonate ? (RAM : H=1.0, C=12.0, O=16.0, Na=23.0, Molar volume of a gas at room temperature and atmospheric pressure = 24.0 dm3) (4 marks) 2. (c) In some cities, the air is often polluted by oxides of nitrogen. (i) Name an oxide of nitrogen that causes air pollution. (ii) Briefly explain how nitrogen oxides may be formed (1) in cities with heavy traffic, and (2) in nature. (iii)Suggest TWO harmful effects of nitrogen oxides in the atmosphere. (6 marks) 4. (a) During World War I, a German chemist, Haber, developed the following process as a source of nitrogen compounds : (i) Write a balanced equation for the reaction between nitrogen and hydrogen in the above process. (ii) Name a catalyst for the reaction. (iii)Explain why high pressure is used in the process. (iv) What is the function of (1) the cooling unit ? (2) the return pump? (v) With the aid of a labelled diagram, show how aqueous ammonia can be prepared from an ammonium salt in the laboratory, and write the equation for the formation of ammonia. (vi) During World War 1, nitrogen compounds were in great demand. Suggest TWO possible reasons. (12 marks) Fertilizers and Gas Volume : 1987

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1. (a) A sample of a gaseous fuel, obtained from the fermentation of animal waste, was known to contain methane, carbon dioxide and nitrogen only. The following experiment was carried out to determine the composition of the sample. s y rin g e A

e x c e ss c o p p e r(II) o x id e

c o m b u s tio n tu b e

3 -w a y ta p

s y rin g e B

s o d a lim e (a m ix tu re o f c a lc iu m o x id e a n d s o d iu m h y d ro x id e )

Step I 100 cm3 of the sample, measured at room temperature and pressure were slowly passed, to and fro, between syringe A and syringe B at room temperature for some time. The gaseous volume was seduced to 84 cm3. Step II The copper(II) oxide was then heated. The remaining gaseous mixture was passed repeatedly from syringe to syringe until tile gaseous volume became constant. After cooling to roam temperature, the final gaseous volume was 4 cm3 (i) Referring to step I, explain the change in the gaseous volume and write an appropriate equation for the reaction involved. (ii) Referring to step II, (1) write an equation for the reaction that occurred in the combustion tube. (2) why was excess copper(II) oxide used ? (3) give two reasons why the final gaseous volume was measured at room temperature. (4) give the name of the gas that was left at the end of the experiment. (iii)Calculate the mole ratio of methane to carbon dioxide in the sample. (iv) Why was a 3-way tap used in this experiment? (10 marks) 2. (c) A student converted lead(II) nitrate to lead(II) sulphate by the experiment described below: 3.31 g of pure lead(II) nitrate were dissolved in distilled water and an excess of sodium sulphate solution was added. The white precipitate formed was filtered, washed, and heated to dryness. its mass was found to be 2.90 g. (Relative atomic masses : N = 14.0, 0 = 16.0, S = 32.0. Pb = 207.0) (i) Explain why (1) an excess of sodium sulphate solution was added. (2) it was necessary to wash the precipitate. (3) the precipitate was dried. (ii) From the above information, calculate the theoretical mass of lead(II) sulphate that could be obtained. (iii)Suggest why the amount of lead(II! sulphate obtained was less than the theoretical value. (7 marks) Fertilizers and Gas Volume : 1988 1. (b)

Fertilizers and Gas Volume

The chart below shows two routes by which atmospheric nitrogen is converted to fertilizers that can be used by plants : (i) What is the natural process that can convert atmospheric nitrogen to nitric acid in Route I? Write balanced equations to illustrate this process.

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Atmospheric nitrogen Route I Nitric acid

Nitrates

Route II Ammonia

Ammonium compounds

Fertilizers used (ii) (1) Name the industrial process for the by plants conversion of atmospheric nitrogen to ammonia in Route II, and write a balanced equation for the conversion. (2) Knowing that this process is exothermic, give TWO conditions that can theoretically give a high yield of ammonia and explain your answer.

(iii)Assuming that the effectiveness of a fertilizer is directly proportional to its nitrogen content per unit mass, determine by calculation whether ammonium nitrate [NH4NO3] or urea [(NH2)2CO] is the more effective fertilizer. (Relative atomic masses : H=1, C=12, N=14, O=16) (13 marks) 4. (c) In a space shuttle, the exhaled air from an astronaut is circulated through lithium hydroxide filters to remove carbon dioxide according to the following equation : 2LiOH(s) + CO2(g) → Li2CO3(s) + H2O(l) (i) Calculate the mass of carbon dioxide which could be absorbed by 1 g of lithium hydroxide. (ii) If potassium hydroxide were used instead of lithium hydroxide, calculate the mass elf carbon dioxide which could be absorbed by 1 g of potassium hydroxide. (iii) Using the results in (i) and (ii), explain why lithium hydroxide is preferred to potassium hydroxide as a carbon dioxide absorbent on board the space shuttle. (iv) Assuming that on the average, an astronaut exhales 502 dm3 of carbon dioxide a day, calculate the mass of lithium hydroxide which must be carried on board a space shuttle for 4 astronauts on a space mission lasting 7 days. (Relative atomic masses : H=1.0, Li= 6.9, C=12.0, O=16.0, K = 39.0; Molar volume of a gas at temperature and pressure of the space shuttle = 24 dm3) (7 marks) Fertilizers and Gas Volume : 1989 5. (a) A student tried to prepare dry ammonia in the laboratory using the following apparatus :

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(i) Suggest suitable solid reactants and a drying agent for this experiment. (ii) Using the apparatus given above only, draw a diagram to show how a gas jar of dry ammonia can be prepared and collected. Include in your diagram the reactants and drying agent suggested in (i)· (iii) Write an equation for the formation of ammonia from the reactants. (iv) Ammonia dissolves readily in water to form an alkaline solution according to the following equation: NH3(g) + H2O(l) ¾ NH4(aq) + OH-(aq) Referring to the above equation, explain the following : (1) The addition of an excess of solid sodium hydroxide to aqueous ammonia would liberate ammonia. (2) The addition of an excess of powdered lead(II) nitrate to aqueous ammonia would lower its pH value. (10 marks) 1. (a) An unknown white solid W was decomposed by heating to about 300oC, as shown in the set-up below: gas Z

At the end of the experiment, a white solid X was left in the boiling tube, a colourless b o ilin g tu b e g a s s y rin g e liquid Y was trapped in the U-tube, and a U -tu b e colourless gas Z was collected in the gas syringe. w h ite u n k n o w n ic e -w a te r m ix tu re s o lid W X was found to contain 11.32% by mass of liq u id Y carbon, 43.40% by mass of sodium, with the rest being oxygen. The relative molar B u n se n b u rn e r mass of X was 106. Liquid Y turned anhydrous copper(II) sulphate blue and gas Z turned lime water milky. (Relative atomic masses : C=12.0, O=16.0, Na=23.0) (i) Based on the experimental observations, deduce what compounds Y and Z might be and write appropriate equations to explain your deductions. (ii) Show by calculation that X is sodium carbonate. (iii) (1) Suggest what W might be. (2) Write a balanced equation for the decomposition of W. (3) Is the decomposition of W a redox reaction? Explain your answer in terms of the oxidation number(s) of the carbon atoms in the reactant and products. (4) Suggest a common use of W in daily life. (iv) To obtain better results, solid W should be heated uniformly. Suggest how this could be achieved. (13 marks) Fertilizers and Gas Volume : 1991 3. (b) The following flow chart represents two different paths for converting sulphur dioxide into sulphuric acid.

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The upper path shows the industrial process for the manufacture of sulphuric acid. (i) Name the industrial process. (ii) (1) Suggest a suitable catalyst in the upper path. (2) The catalytic effect of the catalyst gradually diminishes after some time. Give a reason for this and hence suggest bow its catalytic effect could be prolonged. (iii) Instead of dissolving sulphur trioxide directly in water to form sulphuric acid, sulphur trioxide is absorbed by concentrated sulphuric acid, followed by dilution with water. Give TWO advantages of this method. (iv) The sulphuric acid obtained by this industrial process contains 98% by mass of sulphuric acid and has a density of 1.84 g cm-3). Calculate the volume of the acid required for dilution to 500 cm3 of 0.10 M sulphuric acid. In the laboratory, sulphur dioxide can be converted to sulphuric acid according to the lower path. (v) Write the equation for the reaction involved. (vi) Draw a labelled diagram to show how this reaction can be carried out in the laboratory. (vii) Name a potential hazard associated with this reaction. (Relative atomic masses : H=1.0; O=16.0; S=32.0) (12 marks) Fertilizers and Gas Volume : 1992 2. (a) Consider the following hazard warning labels :

Label A

Label B

Label C

Label D

Choose TWO labels which should be displayed on a bottle of concentrated nitric acid. (3 marks) 2. (b) What would be observed when concentrated nitric- acid is added dropwise to (i) a saturated solution of iron(II) sulphate ? (ii) zinc granules ? Explain the observations and write appropriate equations. (6 marks) 2. (c) 1.0 g of calcium carbonate is added to 50.0 cm3 of 0.1 M nitric acid. At the end of the reaction, 55.0 cm3 of a certain gas are collected at room temperature sad pressure. (i) Draw a diagram of the set-up suitable for this experiment. (ii) Calculate the theoretical volume of the gas which would be liberated at room temperature and pressure.

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(iii) Explain any difference between the theoretical volume and the volume of the gas collected. (Relative atomic masses : C=12.0; O=16.0; Ca=40.0; Molar volume of gas at room temperature and pressure = 24.0 dm3) (6 marks) Fertilizers and Gas Volume : 1993 4. (b) To determine the percentage by mass of calcium carbonate in egg shells, a student added 100 cm3 of 2M hydrochloric acid to 0.3 g of egg shells in a container. After 30 minutes, all the egg shells dissolved and 67 cm3 of carbon dioxide were collected at room temperature and pressure. (i) Write an equation for the reaction between calcium carbonate and hydrochloric acid. (ii) Calculate the percentage by mass of calcium carbonate in the egg shells. (iii)The rate of reaction between the egg shells and 2 M hydrochloric acid was slow. Suggest TWO methods to increase the rate of this reaction without using other chemicals. Explain your answer in each case. (RAM : H=1.0; C=12.0; O=16,O; Ca = 40.0; Molar volume of gas at room temperature and pressure 24.0 dm3) (8 marks) Fertilizers and Gas Volume : 1994 2. For each of the following experiments, decide and explain which of the experimental set-ups, X or Y, should be used.

Fertilizers and Gas Volume : 1995 7. (a) The label on a bottle of 'Effervescent Calcium' tablets is shown below. Effervescent Calcium Each bottle contains 10 tablets. Each tablet contains :

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Calcium carbonate Vitamin C Citric acid

625 mg 1000 mg 1350 mg

Dosage: 1 tablet daily Administration : Dissolve one tablet in a glass of water. Warning : (1) Keep out of reach of children. (2) Keep ........................... (i) Effervescence occurs when a tablet of ‘Effervescent Calcium’ is added to water. Based on the information given on the label, explain why effervescence occurs. Write the ionic equation for the reaction that occurs. (ii) Suppose that a student puts a tablet of ‘Effervescent Calcium’ into an excess amount of water and collects the gas liberated. (1) Assuming that the tablet completely dissolves, calculate the theoretical volume of gas liberated. (2) It is found that the volume of gas collected in the experiment is less than the theoretical volume calculated in (1). Give ONE reason to explain the difference, assuming that there is no leakage of gas in the experiment. (iii)On the label, some words art: missing in the second warning statement. Complete the second warning statement, beginning with the word 'Keep'. Explain your answer. (Relative atomic masses : C=12.0, O=16.0, Ca=40.0; Molar volume of gas at room temperature and pressure 24.0 dm3) (9 marks)

Fertilizers and Gas Volume : 1996 7. (a) The boxes below show some information about two atoms hydrogen (H) and deuterium (D) :

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(i) Suggest a term to indicate the relationship between a hydrogen atom and a deuterium atom. (ii) State the number of neutrons in a deuterium atom. (iii) Deuterium reacts with oxygen in the same way as hydrogen. 2D2(g) + O2(g) → 2D2O(l) ∆H is negative The product of the reaction is known as 'heavy water'. (1) Explain why deuterium reacts with oxygen in the same way as hydrogen. (2) Draw the electronic structure of 'heavy water', showing electrons in the outermost shells ONLY. (3) What is meant by ‘∆H is negative’ ? (4) What is the formula mass of ‘heavy water' ? (5) 100 cm3 of deuterium and 100 cm3 of oxygen, both measured at room temperature and pressure, are allowed to react. Calculate the mass of 'heavy water' produced. (Relative atomic mass : O=16.0; Molar volume of gas at room temperature and pressure = 24.0 dm3) (9 marks) 8. (a) The table below lists some information about four nitrogen-containing compounds which may be used as fertilizers. Solubility in water at Cost per kg of Cost per kg of nitrogen Compound o -3 25 C /mol dm compound /$ in the compound /$ NH3 31.1 12.0 14.6 NH4NO3 26.8 20.0 x (NH4)2SO4 5.8 15.0 70.7 (NH4)2HPO4 4.4 141.0 664.7 (i) Explain why nitrogen is essential for the growth of plants. (ii) Calculate the value of x . (iii) Suggest TWO reasons why farmers do not prefer using ammonia (gas or solution) directly as a fertilizer. (iv) The growth of some plants such as turnips requires a large amount of nitrogen. Which of the four compounds is the most suitable for use as a fertilizer for those plants ? Explain your answer. (Relative atomic masses : H=1.0, N=14.0, O=16.0) (8 marks) Fertilizers and Gas Volume : 1997 6. (b)

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In a certain country, sulphuric acid is manufactured by the Contact Process using sulphur as the raw material. The uses of sulphuric acid in this country are summarised in the following pie-chart. (i) The stages involved in the Contact Process can be represented by the following equations : S(s) + O2(g) → SO2(g) 2SO2(g) + O2(g) ¾ 2SO3(g) SO3(g) + H2SO4 () → H2S2O7() H2S2O7() + H2O() → 2H2SO4() Suppose that the conversion of sulphur to sulphuric acid is 100%. (1) How many moles of sulphur are required to produce one mole of sulphuric acid? (2) If the annual production of sulphuric acid in this country is 2.6×109 kg, calculate the annual consumption of sulphur, in kg, in the Contact Process. (3) Referring to the above equations, explain why the actual annual consumption of sulphur is greater than the value calculated in (2). (ii) Suggest ONE other method that can be used to produce sulphur dioxide required for the Contact Process. Write the chemical equation(s) involved. (iii)As we enter the twentieth century, global demand for fertilizers is increasing annually. (1) Name ONE fertilizer which can be made from sulphuric acid. (2) Explain why global demand for fertilizers is increasing annually. (iv) Sulphuric acid is also used in the paint industry. Suggest ONE paint additive that can be prepared from sulphuric acid. (v) Suggest ONE use of sulphuric acid categorized as ‘Others’ in the pie chart. (Relative atomic masses: H= 1.0, O= 16.0, S= 32.1) (10 marks)

Fertilizers and Gas Volume : 1998 6. (a) (ii) Sodium nitrate is a nitrogenous fertilizer. (a) Calculate the percentage by mass of nitrogen in sodium nitrate. (b) Explain why nitrogen is essential for the growth of plants. (Relative atomic masses : N=14.0, O=16.0, Na=23.0) (3 marks) Fertilizers and Gas Volume : 1999 8. (b) Manufacturing ammonia by the Haber Process involves the following exothermic reaction:

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N2(g) + 3H2(g) ¾ 2NH3(g) (i) (1) Name a catalyst used in the process. (2) Suggest how the heat liberated in the reaction can be used in the process. (ii) A sufficient amount of hydrogen and 6.0×109 dm3 of nitrogen, measured at room temperature and pressure, are allowed to react in the reaction chamber to give ammonia. Suppose that the conversion of nitrogen to ammonia is 15%. Calculate the mass of ammonia formed. (iii) Upon reaction with a suitable chemical, ammonia gives a nitrogenous fertilizer. Write a chemical equation for such a reaction. (iv) Most window cleaners contain ammonia solution as an active ingredient. (1) Explain why ammonia solution is used in window cleaners. (2) State ONE reason for using ammonia solution instead of sodium hydroxide solution in window cleaners. (Relative atomic mass : H=1.0, N=14.0; Molar volume of gas at room temperature and pressure = 24.0 dm3) (9 marks)

Fertilizers and Gas Volume : 2000 9. (a) X, Y and Z are three different metals. The table below shows the results of two experiments carried out using the metals or their oxides. Experiment Adding the metal to water Heating the metal oxide

X Effervescence No observable change

Y No observable change Metal produced

Z No observable change No observable change

(i) Based on the above information, arrange the three metals in order of increasing reactivity. Explain your answer. (ii) An oxide of Y has the formula YO. When 1.08 g of this oxide is heated strongly, it decomposes completely to give 60.0 cm3 of oxygen, measured at room temperature and pressure. Calculate the relative atomic mass of Y. (Relative atomic mass : O=16.0; Molar volume of gas at room temperature and pressure = 24.0 dm3) (6 marks) 9. (c) Nitrogen constitutes about 78% of the atmosphere. The flow diagram below shows the conversion of atmospheric nitrogen to plant proteins. Atmospheric nitrogen

Nitrates in soil

Plant proteins

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(i) Draw the electronic diagram for a molecule of nitrogen, showing electrons in the outermost shells only. (ii) Describe ONE process by which atmospheric nitrogen can be converted to nitrates in soil. (iii) When plants are eaten by animals, the plant proteins are transformed into animal proteins. State ONE way by which the nitrogen in animal proteins can return to soil. (4 marks) 9. (d) Fritz Haber, a German chemist, discovered the transformation of atmospheric nitrogen to ammonia which can be used to produce nitrogenous fertilizers and explosives. He also managed to successfully use chlorine and mustard gas as chemical weapons. In 1918, when he was awarded the Nobel Prize for chemistry, several other Nobel Prize winners refused to accept their awards because of Haber’s involvement. State whether or not you agree that Haber’s inventions contributed to the well-being of the world. Explain your answer. (2 marks)