MARIYA INTERNATIONAL SCHOOL Work sheet II Term II Level 8 Chemistry [Paper IV] Name: SULFUR AND AIR AND WATER 1. Nitrogen dioxide and other oxides of nitrogen are formed in car engines. a) Explain how these oxides are formed. b) How are they removed from the exhaust gases?... 2. Sulfur is used to make sulfuric acid. In the UK, the annual production of the acid is about 2.5 million tonnes. a) The reactions in the manufacture of sulfuric acid by the Contact Process are shown below. I. Give a large scale source of the element sulfur. II. State another use of sulfur dioxide.
III. How is sulfur changed into sulfur dioxide? IV. Name the catalyst used in reaction 2. V. Reaction 2 is exothermic. Why is a catalyst, rather than a higher temperature, used to increase the rate of this reversible reaction? VI. Write a word equation for reaction 3. VII. Write a symbol equation for reaction 4. b) About one third of this production of acid is used to make nitrogen and phosphorus containing fertilizers. I. Name the third element that is essential for plant growth and is present in most fertilizers. II. Name a nitrogen-containing fertilizer that is manufactured from sulfuric acid. 3. Sulfuric acid is manufactured by the Contact Process. Sulfur dioxide is oxidized to sulfur trioxide by oxygen. a) Name the catalyst used in this reaction.
b) What temperature is used for this reaction? c) Describe how sulfur trioxide is changed into sulfuric acid. 4. Sulfuric acid is made by the Contact process in the following sequence of reactions. a) (i) How is sulfur dioxide made from sulfur? (ii) Sulfur dioxide has other uses. Why is it used in the manufacture of paper? (iii) How does it preserve food? (b) The equation for a stage of the Contact process is The percentage of sulfur trioxide in the equilibrium mixture varies with temperature. I. How does the percentage of sulfur trioxide in the equilibrium mixture vary as the temperature increases? Circle the correct answer. increases stays the same decreases
II. Is the forward reaction in the equilibrium exothermic or endothermic? Give a reason for your choice... III. Explain, mentioning both rate and percentage yield, why the temperature used in the Contact process is 450 C... IV. Describe how the sulfur trioxide is changed into concentrated sulfuric acid.... 5. Sulfuric acid is a typical strong acid. Change the equations given into a different format. i. Mg + H2SO4 MgSO4 + H2 Change into a word equation. ii. lithium oxide + sulfuric acid lithium sulfate + water Change into a symbol equation. iii. Na2CO3 + H2SO4 Na2SO4 + CO2+ H20 Change into a word equation..
6. Sulfur dioxide is used to make sulfur trioxide in the Contact Process. The forward reaction is exothermic. The conditions used are: temperature: 450 C pressure: 2 atmospheres catalyst: vanadium(v) oxide Explain, mentioning both position of equilibrium and rate, why these conditions give the most economic yield....... 7. Ozone is a form of oxygen. Ozone is present in the upper atmosphere and it prevents dangerous solar radiation from reaching the Earth s surface. Some of the chemicals that diffuse into the upper atmosphere decompose ozone. Chemicals that have this effect are methane (CH4), chloromethane (CH3Cl ) and an oxide of nitrogen (NO2). i. The oxides of nitrogen are atmospheric pollutants. Describe how they are formed... ii. Complete the equation for the decomposition of ozone.... O3... 8. Sulfuric acid is produced by the Contact process. The steps of the Contact process are shown. (a) Sulfur is a common starting material for the Contact process. Name a source of sulfur....
(b) Describe step 2, giving reaction conditions and a chemical equation. Reference to reaction rate and yield is not required. (c) Step 3 involves adding sulfur trioxide to concentrated sulfuric acid to form oleum. Complete the chemical equation for this reaction. H2SO4 + SO3... 9. A) Ammonia, NH3, is made by reacting nitrogen with hydrogen in the Haber process. (i) Write a chemical equation for the formation of ammonia in the Haber process. (ii) Name the raw materials from which nitrogen and hydrogen are obtained. Nitrogen... Hydrogen... (iii) State the temperature and pressure used in the Haber process. Include the units. Temperature... Pressure... (b) Ammonia is also made when ammonium carbonate decomposes. (NH4)2CO3(s) 2NH3(g) + H2O(g) + CO2(g) The reaction is reversible and can reach a position of equilibrium. The graph shows how the yield of ammonia at equilibrium changes with temperature and pressure.
(i) What is meant by the term equilibrium for a reversible reaction? (ii) Using information from the graph, explain whether the reaction is endothermic or exothermic. (iii) State and explain the effect of increasing the pressure on the yield of ammonia in this reaction. 10. Sulfur dioxide is used to make sulfur trioxide in the Contact Process. The forward reaction is exothermic. The conditions used are: Temperature: 450 C Pressure: 2 atmospheres Catalyst: vanadium(v) oxide Explain, mentioning both position of equilibrium and rate, why these conditions give the most economic yield.