6.2. Rate of reaction
A subsection of Chemistry, 0620, through 6. Chemical reactions
Listing 10 of 319 questions
A student used the apparatus shown below to investigate the speed of reaction when large lumps of zinc reacted with excess sulfuric acid. zinc + sulfuric acid → zinc sulfate + hydrogen sulfuric acid zinc gas syringe As the reaction proceeds, describe what happens to the mass of the zinc lumps. the concentration of zinc sulfate in the solution in the fl ask. The student’s results are shown below. time / minutes volume of hydrogen / cm3 Plot a graph of volume of hydrogen against time. Use the axes below. time / minutes volume of hydrogen / cm3 Use your graph to calculate the volume of hydrogen given off after 25 minutes. volume of hydrogen Explain why no more hydrogen was given off after 50 minutes. Describe a test for hydrogen. test result What happens to the speed of the reaction when smaller pieces of zinc are used? some water is added to the sulfuric acid? The reaction between zinc and sulfuric acid is catalysed by copper(sulfate solution. What do you understand by the term catalyst ?
0620_w10_qp_22
THEORY
2010
Paper 2, Variant 2
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A student used the apparatus shown below to investigate the speed of reaction when large lumps of zinc reacted with excess sulfuric acid. zinc + sulfuric acid → zinc sulfate + hydrogen sulfuric acid zinc gas syringe As the reaction proceeds, describe what happens to the mass of the zinc lumps. the concentration of zinc sulfate in the solution in the fl ask. The student’s results are shown below. time / minutes volume of hydrogen / cm3 Plot a graph of volume of hydrogen against time. Use the axes below. time / minutes volume of hydrogen / cm3 Use your graph to calculate the volume of hydrogen given off after 25 minutes. volume of hydrogen Explain why no more hydrogen was given off after 50 minutes. Describe a test for hydrogen. test result What happens to the speed of the reaction when smaller pieces of zinc are used? some water is added to the sulfuric acid? The reaction between zinc and sulfuric acid is catalysed by copper(sulfate solution. What do you understand by the term catalyst ?
0620_w10_qp_23
THEORY
2010
Paper 2, Variant 3
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The decomposition of hydrogen peroxide is catalysed by manganese(oxide. 2H2O2→ 2H2O+ O2To 50 cm3 of aqueous hydrogen peroxide, 0.50 g of manganese(oxide was added. The volume of oxygen formed was measured every 20 seconds. The average reaction rate was calculated for each 20 second interval. time / s volume of oxygen / cm3 average reaction rate in cm3 / s 2.4 1.1 0.3 0.0 0.0 Explain how the average reaction rate, 2.4 cm3 / s, was calculated for the fi rst 20 seconds. Complete the table. Explain why the average reaction rate decreases with time. The experiment was repeated but 1.0 g of manganese(oxide was added. What effect, if any, would this have on the reaction rate and on the fi nal volume of oxygen? Give a reason for each answer. effect on rate reason effect on fi nal volume of oxygen reason
0620_w10_qp_32
THEORY
2010
Paper 3, Variant 2
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A pupil studied the effect of temperature on the speed of reaction of aqueous sodium thiosulfate with dilute hydrochloric acid. When he added hydrochloric acid to a solution of sodium thiosulfate, a precipitate of sulfur gradually formed. He recorded the time taken for some writing placed under the fl ask to disappear from view. experiment experiment sodium thiosulfate solution precipitate of sulfur add hydrochloric acid He repeated the experiment at different temperatures. The table shows his results. temperature / °C time taken for the writing to disappear from view / s On the grid below, plot a graph of the time taken against temperature. temperature / °C time taken / s At which temperature was the reaction the fastest? Describe how the temperature affects the speed of reaction. Suggest how the speed of this reaction at 30 °C will change when the concentration of hydrochloric acid is increased. The equation for the reaction is Na2S2O3+ 2HCl → 2NaCl + SO2+ S+ H2OState the name of the salt formed in this reaction. To which group in the Periodic Table does sulfur belong? Sulfur dioxide is formed when coal is burnt in power stations. State one harmful effect of sulfur dioxide on the environment. Sulfur dioxide can be removed in power stations by fl ue gas desulfurisation. Which one of these compounds is used to remove the sulfur dioxide in this process? Tick one box. calcium chloride calcium oxide nitrogen dioxide potassium nitrate Magnesium burns in sulfur dioxide. 2Mg + SO2 → 2MgO + S Refer to this equation to explain why this is a redox reaction.
0620_w11_qp_21
THEORY
2011
Paper 2, Variant 1
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