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Which compound is not a fertiliser?
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Acid rain is formed when sulfur dioxide and oxides of nitrogen dissolve in rain water.
Which problem is not caused by acid rain?
Which problem is not caused by acid rain?
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IGCSE CHEMISTRY
CHAPTER 12
| Question | Answer |
|---|---|
| Which compound is not a fertiliser? | Calcium hydroxide, Ca(OH)2 |
| Acid rain is formed when sulfur dioxide and oxides of nitrogen dissolve in rain water. Which problem is not caused by acid rain? | Breathing difficulties |
| True or false; The burning of fossil fuels containing sulfur is a cause of ‘acid rain’ | True |
| True or false; Acid rain contains sulfur dioxide which is formed when sulfur compounds burn in the air | True |
| Sulfur is a common starting material for the Contact process. Name a source of sulfur | Fossil fuels |
| Describe step 2, giving reaction conditions and a chemical equation. Reference to reaction rate and yield is not required | Vanadium pentoxide 450 °C (units required); |
| Dilute sulfuric acid is a typical acid. A student adds excess dilute sulfuric acid to a sample of solid copper(II) carbonate in a test-tube. Give three observations the student would make. | Bubbles Dissolves Blue solution |
| Dilute sulfuric acid is a typical acid. A student adds excess dilute sulfuric acid to a sample of solid copper(II) carbonate in a test-tube. Give the names of all products formed | Carbon dioxide Water Copper(II) sulfate |
| Concentrated sulfuric acid has different properties to dilute sulfuric acid. When concentrated sulfuric acid is added to glucose, C6H12O6, steam is given off and a black solid is formed. What type of reaction has occurred? | Dehydration |
| Sulfuric acid is made by the Contact process. Sulfur is burned by spraying droplets of molten sulfur into air. Suggest and explain two advantages of using this method. | Fast reaction; Larger surface area; |
| Sulfur dioxide is more expensive than air. What is the three advantage of using an excess of air? | Moves equilibrium to right; Increases yield (of sulfur trioxide) Uses up more sulfur dioxide; |
| The forward reaction is exothermic. The reaction is usually carried out at a temperature between 400 and 450 °C. What is the two effect on the position of equilibrium of using a temperature above 450 degrees C? Explain your answer. | Moves equilibrium to left; Forward reaction exothermic; |
| The forward reaction is exothermic. The reaction is usually carried out at a temperature between 400 and 450 °C. (ii) What is the four effect on the rate of using a temperature below 400 Degrees C? Explain your answer. | Molecules have less energy and move slower; Fewer collisions (per second) Fewer particles have the activation energy Fewer collisions have the activation energy; |
| A low pressure, 2 atmospheres, is used. At equilibrium, about 98% SO3 is present. What is the effect on the position of equilibrium of using a higher pressure? | Moves to right; |
| A low pressure, 2 atmospheres, is used. At equilibrium, about 98% SO3 is present. Explain why a higher pressure is not used | High yield at 2 atm; |
| Name the catalyst used in the Contact process | Vanadium(V) oxide |
| Describe in three points how concentrated sulfuric acid is made from sulfur trioxide | Dissolve React sulfur trioxide in concentrated sulfuric acid; Add water to product |
| The main use of sulfur dioxide is the manufacture of sulfuric acid. State two other uses of sulfur dioxide. | Bleach Making wood pulp |
| One source of sulfur dioxide is burning sulfur in air. Describe how sulfur dioxide can be made from the ore zinc sulfide | Heating or roasting or burning (zinc sulfides) in air Oxygen COND |
| Suggest six advantages of using a high pressure? Explain your suggestions | Faster reaction rate More collisions per second Higher collision frequency fewer moles Molecules (of gas) on right Position of equilibrium shifts right Yield increases |
| Sulfuric acid is made by dissolving sulfur trioxide in concentrated sulfuric acid to form oleum. Water is reacted with oleum to form more sulfuric acid. Why is sulfur trioxide not reacted directly with water? Name 2 points. | The reaction is too violent and too exothermic Produces mist and fumes of acid |
| Sulfuric acid is an important acid, both in the laboratory and in industry. Its manufactured in the Contact Process. it was made by heating metal sulfates and by burning a mixture of sulfur and potassium nitrate. Give a major use of sulfuric acid. | Making fertilisers |
| When the iron(II) sulfate is heated strongly, further decomposition occurs. 2FeSO4(s) - Fe2O3(s) + SO2(g) + SO3(g) The gases formed in this reaction react with water and oxygen to form sulfuric acid. Explain how the sulfuric acid is formed. | Sulfur trioxide reacts with water to make sulfuric acid or equation Sulfur dioxide reacts with oxygen to form sulfur trioxide or equation |
| When a mixture of sulfur and potassium nitrate is burned and the products are dissolved in water, sulfuric acid is formed. The sulfuric acid formed by this method is not pure. It contains another acid. Deduce the identity of this acid. | Nitric acid |
| When a mixture of sulfur and potassium nitrate is burned and the products are dissolved in water, sulfuric acid is formed. The heat causes some of the potassium nitrate to decompose. Write the equation for the action of heat on potassium nitrate | 2KNO3 = 2KNO2 + O2 |
| Sulfuric andHexanesulfonic acidis a strong acid. It has similar properties to sulfuric acid. Sulfonic acids are made from alkanes and oleum, H2S2O7. C6H14 + H2S2O7 C6H13SO3H + H2SO4 Describe how oleum is made from sulfur by the Contact process. | S + O2 € SO2 sulfur burnt in air to form sulfur dioxide 2SO2 + O2 =2SO3 unbalanced = (1) only vanadium pentoxide (temperature) 440 to 460 oC (dissolve) sulfur trioxide in sulfuric acid (to form oleum) |
| How is concentrated sulfuric acid made from oleum? | Add oleum to water |
| Sulfuric acid is a strong acid. You are given aqueous sulfuric acid, concentration 0.1 mol / dm3, and aqueous hexanesulfonic acid, concentration 0.2 mol / dm3. Describe how you could show that hexanesulfonic acid is also a strong acid | Measure rate with named reactive metal, Mg, Zn Both fast reactions |
| Deduce why, for a fair comparison, the two acid solutions must have different concentrations | |
| Explain the terms strong acid | A strong acid is completely ionised, |
| Explain the terms weak acid | A weak acid is partially ionised |
| The food additive E220 is sulfur dioxide. It is a preservative for a variety of foods and drinks. State two other uses of sulfur dioxide. | Bleaching of wood pulp Manufacture of sulfuric acid |
| How is sulfur dioxide manufactured? | Burn or heat or react sulfur; In air oxygen |
| Sulfur dioxide is a reductant (reducing agent). Describe what you would see when aqueous sulfur dioxide is added to acidified potassium manganate(VII). | From purple or pink to colourless; |
| Zinc blende is heated in air. Zinc oxide and sulfur dioxide are formed. Write the balanced equation for this reaction | 2ZnS + 3O2 → 2ZnO + 2SO2 |
| Zinc oxide is reduced to zinc by heating with carbon. Name two other reagents which could reduce zinc oxide | Two reagents from named metal(s) more reactive to form zinc orcarbon monoxide |
| Sulfur is needed for sulfuric acid. Two major sources of sulfur ● underground deposits of the element sulfur, ● sulfur compounds from natural gas and petroleum. Explain why sulfur and its compounds are removed from these fuels before they are burned | Burns to form sulfur dioxide Acid rain Any problem associated with acid rain Sulfur dioxide is poisonous |
| Sulfur dioxide is made by spraying molten sulfur into air. The sulfur ignites and sulfur dioxide is formed. Suggest why molten sulfur is used in the form of a fine spray | Bigger surface area Burns and reacts faster Greater number of collisions |
| Explain why traces of sulfur dioxide act as a preservative in fruit juices. | Kills bacteria. Anti-oxidant Stops oxygen oxidising juice Prevents growth of bacteria |
| State another use of sulfur dioxide | Bleach Refrigerant Making wine Fumigant Insecticide Dyes |
| Describe how sulfur dioxide is changed into sulfur trioxide. Give the reaction conditions and an equation | 2SO2 + O2 € 2SO3 Temperature 400 to 450 C Pressure 1 to 10 atmospheres |
| The major use of sulfur dioxide is to manufacture sulfuric acid. Another use of sulfur dioxide is as the food additive E220. How does it preserve food? | It kills bacteria |
| Why is sulfur dioxide used in the manufacture of wood pulp? | Its been used as a bleach |
| Define the term acid | Proton donor |
| Suggest an explanation why sulfurous acid in contact with air changes into sulfuric acid. | Reacts with oxygen in air |
| Sulphur dioxide has other uses. Why is it used in the manufacture of paper? | Its been used as a bleach |
| How does Sulphur dioxide preserve food? | It kills the bacteria |
| Describe how the sulphur trioxide is changed into concentrated sulphuric acid. | Bubble into (conc) sulphuric acid |
| Explain, mentioning both rate and percentage yield, why the temperature used in the Contact process is 450°C | Low enough for good yield High enough for (economic) rate |
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Haridus Academy