6.2. Rate of reaction
A subsection of Chemistry, 0620, through 6. Chemical reactions
Listing 10 of 319 questions
The rate of decomposition of aqueous hydrogenperoxide, H2O2, is increased by an enzyme. 2H2O2 → 2H2O + O2 The rate of reaction is found by measuring the volume of oxygen gas given off as the reaction proceeds. The results are shown on the graph. time / s volume of oxygen gas / cm3 Deduce the volume of oxygen gas released when the reaction is complete.  volume = cm3 Deduce the volume of oxygen gas produced 50seconds from the start of the reaction.  volume = cm3 The experiment was repeated using hydrogenperoxide of a higher concentration. All other conditions stayed the same. Draw a line on the grid to show how the volume of oxygen changes with time when hydrogenperoxide of a higher concentration is used. Describe the effect each of the following has on the rate of decomposition of hydrogen peroxide. ● The reaction is carried out at a lower temperature. All other conditions stay the same. ● The reaction is carried out without an enzyme. All other conditions stay the same.  Some metal oxides catalyse the decomposition of hydrogenperoxide. The table shows the time taken to produce 20 cm3 of oxygen gas using three different metal oxide powders as catalysts. All other conditions stay the same. metal oxide time taken to produce 20 cm3 of oxygen gas / s iron(oxide lead(oxide manganese(oxide Put the three oxides in order of their ability to catalyse the reaction. Put the best catalyst first. best catalyst worst catalyst  The experiments with the metal oxide catalysts used powdered oxide. Describe the effect on the rate of decomposition of hydrogenperoxide when large pieces of catalyst are used instead of powdered catalyst. All other conditions stay the same. 
0620_w21_qp_31
THEORY
2021
Paper 3, Variant 1
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A student investigated the reaction of small pieces of calciumcarbonate with dilute hydrochloricacid. The hydrochloric acid was in excess. CaCO3 + 2HCl → CaCl 2 + CO2 + H2O The rate of reaction is found by measuring the decrease in the mass of the reaction mixture with time. The results are shown on the graph. time / s mass of reaction mixture / g Deduce the time taken from the beginning of the experiment for the mass of the reaction mixture to decrease by 1.0 g.  time = s The experiment was repeated using dilute hydrochloricacid of a higher concentration. All other conditions stayed the same. Draw a line on the grid to show how the mass of the reaction mixture changes with time using acid of a higher concentration. Describe the effect each of the following has on the rate of reaction of calciumcarbonate with hydrochloricacid. All other conditions stay the same. ● The reaction is carried out at a higher temperature. ● The reaction is carried out using large pieces of calciumcarbonate instead of small pieces of calciumcarbonate.  When 0.44 g of calciumcarbonate is used, 100 cm3 of carbondioxide gas is formed. Calculate the mass of calciumcarbonate needed to produce 25 cm3 of carbondioxide gas.  mass of calcium carbonate = g The table compares the reaction of four metals with dilute hydrochloricacid. metal observations iron bubbles produced slowly magnesium bubbles produced very rapidly nickel bubbles produced very slowly silver no bubbles produced Put the four metals in order of their reactivity. Put the least reactive metal first. least reactive most reactive  
0620_w21_qp_32
THEORY
2021
Paper 3, Variant 2
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A student investigated the reaction of small pieces of zinc with dilute hydrochloric acid. The hydrochloric acid was in excess. Zn + 2HCl → ZnCl 2 + H2 The rate of reaction is found by measuring the increase in volume of hydrogen gas with time. The results are shown on the graph. time / s volume of hydrogen gas / cm3 Deduce the time taken from the beginning of the experiment to collect 30 cm3 of hydrogen gas.  time = s The experiment was repeated using dilute hydrochloricacid of a higher concentration. All other conditions stayed the same. Draw a line on the grid to show how the volume of hydrogen gas changes with time. Describe the effect each of the following has on the rate of reaction of zinc with dilute hydrochloricacid.  All other conditions stay the same. ● The reaction is carried out at a lower temperature. ● The reaction is carried out using zinc powder instead of small pieces of zinc.  When 0.065 g of zinc is used, 24 cm3 of hydrogen gas is formed. Calculate the mass of zinc needed to produce 96 cm3 of hydrogen gas.  mass of zinc = g Aqueous ammonia is added to aqueous zincchloride. Describe the observations when a few drops of aqueous ammonia are added and when excess aqueous ammonia is added. a few drops of aqueous ammonia excess aqueous ammonia  
0620_w21_qp_33
THEORY
2021
Paper 3, Variant 3
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A student investigates the decomposition of hydrogenperoxide in the presence of a catalyst of manganese(oxide. 2H2O2→ 2H2O+ O2State the meaning of the term catalyst. The diagram shows the equipment the student uses. aqueous hydrogen peroxide cotton wool balance catalyst of manganese(oxide The student uses this method: ● the catalyst is added to the aqueous hydrogen peroxide ● the stop-clock is started ● the mass of the flask and contents is recorded at regular time intervals. A graph of the mass of the flask and contents against time is shown. mass of the flask and contents / g time / s Suggest why the mass of the flask and contents decreases as time increases. Describe what happens to the rate of the reaction as time increases. The student repeats the experiment at a higher temperature. All other conditions stay the same. The rate of reaction increases. Explain, in terms of collisions between particles, why the rate of reaction increases at a higher temperature. Draw a line on the graph in for the experiment at a higher temperature. 
0620_w21_qp_43
THEORY
2021
Paper 4, Variant 3
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319