6.2. Rate of reaction
A subsection of Chemistry, 0620, through 6. Chemical reactions
Listing 10 of 319 questions
Large pieces of solid sulfur burn in excess oxygen to produce sulfur dioxide gas. Complete the equation by adding the missing state symbol. S( ) + O2→ SO2 shows how the mass of sulfur changes as the reaction proceeds. time / seconds mass of sulfur / g Deduce the time taken for the reaction to finish. The experiment is repeated using powdered sulfur. Describe the effect on the rate of reaction of using powdered sulfur rather than large pieces of sulfur. Sulfur dioxide reacts with oxygen in a closed container. 2SO2+ O22SO3Describe the effect, if any, each of the following has on the rate of this reaction. All other conditions stay the same. ● The temperature is decreased. ● The pressure of the gases is increased.  Changing concentration changes the rate of a reaction. Choose the correct unit of concentration from the list. Draw a circle around your chosen answer. dm3 / mol mol / dm mol / dm2 mol / dm3 Sulfur dioxide is an air pollutant. State one adverse effect of sulfur dioxide. Emissions of sulfur dioxide can be reduced by using low-sulfur fossil fuels. State one other way of reducing sulfur dioxide emissions from fossil fuels. Aqueous sodium hydrogen sulfite releases sulfur dioxide gas at room temperature. Sulfur dioxide changes the colour of acidified potassium manganate(from purple to colourless. shows a sealed tube with a small volume of aqueous sodium hydrogen sulfite at the bottom. A piece of filter paper soaked in acidified potassium manganate(is attached to the top of the tube. filter paper soaked in acidified potassium manganate(aqueous sodium hydrogen sulfite The filter paper remains purple at first. The filter paper becomes colourless after a short time. Explain these results in terms of kinetic particle theory. 
0620_s24_qp_31
THEORY
2024
Paper 3, Variant 1
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Solid nitrogen pentoxide, N2O5, decomposes to produce nitrogen dioxide gas and oxygen gas. Complete the equation by adding the missing state symbols. 2N2O5→ 4NO2( ) + O2( ) shows how the mass of nitrogen pentoxide changes as the reaction proceeds. time / minutes mass of nitrogen pentoxide / g On , draw an X to show where the rate of reaction is fastest. Deduce the mass of nitrogen pentoxide 12 minutes from the start of the reaction. At 50 °C, the reactant and products are all gases. Describe the effect each of the following has on the rate of decomposition of nitrogen pentoxide. All other conditions stay the same. ● The pressure is decreased. ● A catalyst is added to the reaction mixture. Increasing the concentration of nitrogen pentoxide increases the rate of decomposition. Choose the correct unit of concentration from the list. Draw a circle around your chosen answer. dm3 / g g / dm g / dm2 g / dm3 Some oxides of nitrogen such as nitrogen dioxide are acidic air pollutants. Choose the pH value which is acidic. Draw a circle around your chosen answer. pH 1 pH 7 pH 8 pH 14 State one way of reducing the emissions of nitrogen dioxide in cars. Nitrogen dioxide is a yellow liquid which evaporates to form a brown gas at room temperature. A long glass tube is set up as shown in . glass tube small dish containing liquid nitrogen dioxide At first, the brown gas can only be seen above the small dish. After a short time, the brown gas has completely filled the tube. Explain these results in terms of kinetic particle theory. , ,
0620_s24_qp_32
THEORY
2024
Paper 3, Variant 2
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Dilute hydrochloric acid reacts with small pieces of calcium carbonate. 2HCl + CaCO3→ CaCl 2+ H2O+ CO2State the meaning of the state symbol . shows how the mass of small pieces of calcium carbonate changes as the reaction proceeds. The calcium carbonate is in excess. time / minutes mass of calcium carbonate / g Deduce the mass of calcium carbonate two minutes from the start of the reaction. Explain how the graph shows that the calcium carbonate is in excess. The experiment is repeated at a higher temperature. All other conditions stay the same. Draw a line on to show how the mass of calcium carbonate changes at a higher temperature as the time increases. Describe the effect, if any, on the rate of reaction when large pieces of calcium carbonate are used instead of small pieces of calcium carbonate. All other conditions stay the same. Increasing the concentration of dilute hydrochloric acid increases the rate of reaction of dilute hydrochloric acid with calcium carbonate. Choose the correct unit of concentration from the list. Draw a circle around your chosen answer. dm3 / g g / dm2 mol / dm mol / dm3 Concentrated hydrochloric acid gives off hydrogen chloride gas. Hydrogen chloride is an acidic gas that turns damp universal indicator paper red. A long glass tube is set up as shown in . concentrated hydrochloric acid universal indicator paper At first, the universal indicator paper does not change colour. The universal indicator paper turns red after a short time. Explain these results in terms of kinetic particle theory. Hydrogen chloride breaks down to form hydrogen and chlorine at 1500 °C. The reaction in endothermic. State the meaning of the term endothermic. 
0620_s24_qp_33
THEORY
2024
Paper 3, Variant 3
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Use Hydrogen peroxide solution, H2O2, decomposes slowly in the absence of a catalyst. Oxygen and water are formed. 2H2O22H2O+ O2Draw a diagram of the apparatus you could use to investigate the speed of this reaction. You must label your diagram. Catalyst X was added to 50cm3 of hydrogen peroxide solution at 20oC and the amount of oxygen given off was recorded over a two minute period. The experiment was repeated with the same amounts of catalyst Y and catalyst Z. Apart from the type of catalyst, all conditions were kept the same in the three experiments. A graph of the results is shown below. time / seconds volume of oxygen gas / cm3 X Y Z What is a catalyst? Examiner's Use Which catalyst, X, Y or Z, produced oxygen gas the fastest? Explain your answer. Why is the final amount of oxygen gas the same in each experiment? Many transition metals and their oxides are good catalysts. State two other properties of transition metals which are not shown by other metals. The experiment with catalyst Z was repeated at 40oC. All other conditions were kept the same. The speed of the reaction increased. Explain why, using ideas about particles. Some enzymes also catalyse the decomposition of hydrogen peroxide. State one difference between an enzyme and an inorganic catalyst such as a transition metal. Enzymes are also responsible for fermentation reactions. Which one of the following equations A, B, C or D describes fermentation? C6H12O6 + 6O2 A 6CO2 + 6H2O C2H4 + H2O B C2H5OH C6H12O6 C 6C + 6H2O C6H12O6 D 2C2H5OH + 2CO2
0620_w05_qp_2
THEORY
2005
Paper 2, Variant 0
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Use The table gives some information about the properties of some metals. metal melting point /°C colour of chloride A pink B white C white D brownish-black Which two of the metals A to D are transition metals? Give a reason for your answer. metals reason When iron powder reacts with warm sulphuric acid, hydrogen is given off. Fe + H2SO4 FeSO4 + H2 State the name of the salt made in this reaction. Examiner's Use A student used the apparatus shown below for investigating the speed of the reaction between iron and sulphuric acid. water sulphuric acid iron powder Describe how this apparatus can be used to investigate the speed of this reaction. The student repeated the experiment with different concentrations of sulphuric acid. In each experiment the mass of iron powder was the same and the temperature was kept at 30°C. The results are shown in the table. concentration of sulphuric acid / moles per dm3 speed of reaction /cm3 hydrogen per second 0.4 4.2 0.8 8.5 1.6 17.0 Use the information in the table to help you work out how the speed of the reaction is affected by the concentration of sulphuric acid. What will happen to the speed of the reaction if lumps of iron are used instead of iron powder? Examiner's Use What will happen to the speed of the reaction if it is carried out at 20°C rather than at 30°C?
0620_w06_qp_2
THEORY
2006
Paper 2, Variant 0
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Questions Discovered
319