0620_s18_qp_33
A paper of Chemistry, 0620
Questions:
8
Year:
2018
Paper:
3
Variant:
3
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1
The names of seven gases are given. ammonia ethene helium hydrogen hydrogen chloride methane nitrogen Answer the following questions about these gases. Each gas may be used once, more than once or not at all. State which gas: forms an acidic solution in water is monatomic forms 78% of clean dry air is the main constituent of natural gas has molecules which each contain 14 protons. Give the names of two elements in the list. and  What is meant by the term element ? Complete the dot-and-cross diagram to show the electron arrangement in a molecule of hydrogenchloride. Show outer electrons only. H Cl  
11. Organic chemistry  →  11.3. Fuels
8. The Periodic Table  →  8.5. Noble gases
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
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The table shows the percentage by volume of each of the gases present in the exhaust gases from a petrol engine and a diesel engine. name percentage by volume from a petrol engine percentage by volume from a diesel engine nitrogen 72.00 67.00 carbon dioxide 14.00 water vapour 12.00 11.00 carbon monoxide 1.50 0.05 oxides of nitrogen 0.25 0.70 hydrocarbons 0.24 0.22 sulfur dioxide 0.01 0.03 oxygen 0.00 9.00 total 100.00 total 100.00 In the diesel engine, nitrogen, carbon dioxide and water vapour account for 90.00% of the exhaust gases by volume. Calculate the percentage by volume of carbon dioxide in the exhaust gases from the diesel engine.  % Describe three ways in which the composition of the exhaust gases from the petrol engine differ from the composition of the exhaust gases from the diesel engine.  Give one adverse effect of sulfur dioxide on health. Complete the sentences about the separation of petroleum into fractions using words from the list. boiling crystallisation density distillation kerosene polyFractional of petroleum produces fractions such as gasoline, diesel oil and . Within each fraction, the molecules have a particular range of points.  Balance the chemical equation for the complete combustion of propane. C3H8 + 5O2 CO2 + H2O  
11. Organic chemistry  →  11.3. Fuels
10. Chemistry of the environment  →  10.3. Air quality and climate
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This question is about cobalt and its compounds. A coloured crystal of cobalt(chloride was placed at the bottom of a beaker containing water. After 2 days, the colour had spread throughout the water. at the start after 2 hours after 2 days crystal of cobalt(chloride water Explain these observations using the kinetic particle model. Cobalt(chloride can be used to test for the presence of water. CoCl 2 + 6H2O CoCl 2.6H2O anhydrous hydrated cobalt(chloride cobalt(chloride What is meant by the symbol ? Describe how the colour of anhydrous cobalt(chloride changes when water is added to it. from to  A compound of cobalt can be represented by the structure shown. = cobalt, Co = carbon, C = oxygen, O key Deduce the molecular formula of this compound showing the number of cobalt, carbon and oxygen atoms. The table compares the reactivity of cobalt with that of three other metals. metal reactivity with cold water reactivity with steam barium reacts rapidly cobalt no reaction reacts slowly when heated magnesium reacts very slowly reacts rapidly zinc no reaction reacts easily when heated Use this information to put the metals in order of their reactivity. Put the least reactive metal first. least reactive most reactive  Cobalt is a transition element. Lithium is an element in GroupI of the Periodic Table. Describe three ways in which the properties of cobalt differ from those of lithium.  When cobalt(oxide, CoO, is heated in air, an oxide with the formula Co3O4 is formed. Balance the chemical equation for this reaction. CoO + O2 2Co3O4  When Co3O4 is heated with hydrogen, cobalt metal can be formed. Co3O4 + 4H2 3Co + 4H2O How does this equation show that Co3O4 is reduced? 
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
10. Chemistry of the environment  →  10.1. Water
9. Metals  →  9.4. Reactivity series
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This question is about alcohols. The structure of compound P is shown. C O H H C C H H H H What feature of the structure of compound P shows that it is unsaturated? Describe how the colour of aqueous bromine changes when an excess of compound P is added to it. from to  The melting point of compound P is –129 °C. The boiling point of compound P is 97 °C. What is the physical state of compound P at –120 °C? Explain your answer. Ethanol is an alcohol with two carbon atoms. Draw the structure of ethanol showing all of the atoms and all of the bonds.  Ethanol can be manufactured by fermentation. Complete the sentences about fermentation using words from the list. 30 °C 300 °C distillation electrolysis elements enzymes salt sugar A flask containing solution and yeast is heated to . The yeast contains which catalyse the reaction. The ethanol is separated by . Ethanol can be used as a fuel. Give one other use of ethanol in industry. The energy level diagram for the complete combustion of ethanol is shown. energy ethanol + oxygen carbon dioxide + water progress of reaction Explain how this diagram shows that the reaction is exothermic. Carbon dioxide and water can be formed when ethanol burns in a limited supply of air. State the name of two other products which can be formed when ethanol burns in a limited supply of air. and  
11. Organic chemistry  →  11.6. Alcohols
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Molten lead(bromide can be electrolysed using the apparatus shown. molten lead(bromide inert electrodes + – The negative electrode is called the cathode. State the name of the positive electrode. Predict the products of the electrolysis of molten lead(bromide at: the negative electrode the positive electrode.  Lead(bromide is insoluble in cold water. Sodium bromide is soluble in cold water. Describe how you could obtain crystals of sodium bromide from a mixture of solid lead(bromide and solid sodiumbromide. When chlorine is bubbled through a colourless aqueous solution of sodium bromide, the solution turns orange‑brown. Name the orange-brown substance. Suggest, using ideas about reactivity of the halogens, why the reaction occurs. orange-brown substance why the reaction occurs  What is the colour of the precipitate formed when aqueous silver nitrate is added to aqueous sodium bromide? Complete the sentence about the formation of a chloride ion from a chlorine atom. A chloride ion is formed when a chlorine atom gains one . 
4. Electrochemistry  →  4.1. Electrolysis
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This question is about isotopes. An atom of an isotope of oxygen is represented by the symbol shown. 17O Describe the structure of an atom of this isotope of oxygen. In your answer, include: ● ● the position of the protons, neutrons and electrons in the atom ● ● the number of protons, neutrons and electrons present in the atom. Which two statements about isotopes are correct? Tick two boxes. Isotopes of the same element have different numbers of protons. Isotopes of the same element have different numbers of neutrons. Isotopes are always radioactive. The isotope 235U 92 is a source of energy. 14C 6 and 14N 7 are isotopes of each other.  What is meant by the term nucleon number? 
2. Atoms, elements and compounds  →  2.3. Isotopes
2. Atoms, elements and compounds  →  2.2. Atomic structure and the Periodic Table
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This question is about GroupI elements and their compounds. The properties of some GroupI elements are shown in the table. element melting point / °C relative hardness observations when it reacts with cold water lithium sodium rapid bubbling but does not burst into flame potassium very rapid bubbling and bursts into flame rubidium bursts into flame and explodes Complete the table to estimate: ● ● the relative hardness of potassium ● ● the melting point of rubidium.  Use the information in the table to predict what you would observe when lithium reacts with cold water. Write the electronic structure of a sodium atom. When sodium reacts with water, an alkaline solution is formed. 2Na + 2H2O 2NaOH + H2 Use the information in the equation to explain why the solution formed is alkaline. Describe how you could use a named indicator solution to show that the solution is alkaline. Sodium tetrahydridoborate, NaBH4, is an ionic compound. Calculate the relative formula mass of NaBH4. Show all your working. Use your Periodic Table to help you.  relative formula mass = 
8. The Periodic Table  →  8.2. Group I properties
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
9. Metals  →  9.4. Reactivity series
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8
The apparatus shown is used to investigate the rate of reaction between calciumcarbonate and hydrochloricacid at 30 °C. water hydrochloric acid A calcium carbonate Name the piece of apparatus labelled A in the diagram. Describe how this apparatus can be used to find the rate of reaction. The experiment is repeated at 20 °C. All other conditions are kept the same. How does the decrease in temperature affect the rate of reaction? The experiment is repeated using the same mass of different size pieces of calciumcarbonate. All other conditions are kept the same. The sizes of the pieces of calciumcarbonate are: ● ● large pieces ● ● small pieces ● ● powder Complete the table by writing the sizes of the pieces in the first column. size of the pieces of calcium carbonate initial rate of reaction in cm3 gas / s  Give the names of the three products formed when calcium carbonate reacts with hydrochloricacid.  
6. Chemical reactions  →  6.2. Rate of reaction
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