6.2. Rate of reaction
A subsection of Chemistry, 0620, through 6. Chemical reactions
Listing 10 of 319 questions
Carboxylic acids react with alcohols to form esters. The reaction is reversible. The equation for the reaction between ethanoic acid and ethanol is shown. CH3COOH + CH3CH2OH CH3COOCH2CH3 + H2O What is the name of the ester formed in this reaction? Draw the structure of the ester formed. Show all of the atoms and all of the bonds.  The reaction between ethanoic acid and ethanol is exothermic. Draw an energy level diagram for this reaction. On your diagram label: ● ● the reactants and products ● ● the energy change of the reaction, ∆H. energy progress of reaction  Concentrated sulfuricacid is a catalyst for this reaction. What is meant by the term catalyst ? The rate of reaction can be increased by increasing the temperature. Explain why increasing the temperature increases the rate of reaction. The reaction between ethanoicacid and ethanol reaches equilibrium. The reaction between ethanoic acid and ethanol is exothermic. State and explain the effect, if any, of increasing the temperature on the amount of ester at equilibrium. State and explain the effect, if any, of removing water from the mixture on the amount of ester at equilibrium. 
0620_s19_qp_43
THEORY
2019
Paper 4, Variant 3
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Acids have characteristic properties. Hydrochloricacid reacts with magnesium. Name the products of this reaction and give the observations. The rate of reaction of iron(carbonate with hydrochloricacid can be determined by measuring the time taken to produce 20 cm3 of carbondioxide. A student measured the time taken to produce 20 cm3 of carbon dioxide at three different temperatures. In each experiment the student used: ● ● 1 g of large pieces of iron(carbonate ● ● dilute hydrochloric acid of the same concentration and volume. The results are shown in the table. temperature / °C time / s Use the information in the table to describe how the rate of reaction changes with temperature. Describe the effect of each of the following on the rate of this reaction at constant temperature. ● ● Smaller pieces of iron(carbonate are used. All other conditions stay the same. ● ● The concentration of hydrochloricacid is decreased. All other conditions stay the same.  The reaction of iron(carbonate with hydrochloricacid is exothermic. What is meant by the term exothermic? Rust contains compounds of iron. State two conditions needed for iron to rust. Iron and magnesium are both used in alloys. Which one of these diagrams, A, B, C or D, best represents an alloy? A B C D 
0620_s20_qp_31
THEORY
2020
Paper 3, Variant 1
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Acids have characteristic properties. Hydrochloric acid reacts with magnesiumcarbonate. Name the products of this reaction and give the observations. The rate of reaction of iron with sulfuricacid can be determined by measuring the time taken to produce 20 cm3 of hydrogen. A student measured the time taken to produce 20 cm3 of hydrogen using three different concentrations of sulfuricacid. In each experiment the student used: ● ● 1 g of iron powder ● ● the same temperature ● ● the same volume of sulfuric acid. The results are shown in the table. concentration of acid in mol / dm3 time / s 0.1 0.2 0.5 Use the information in the table to describe how the rate of reaction changes with the concentration of sulfuricacid. Describe the effect of each of the following on the rate of this reaction with 0.5 mol / dm3 of sulfuricacid. ● ● Larger pieces of iron are used. All other conditions stay the same. ● ● The temperature is increased. All other conditions stay the same.  Heat is given out when iron reacts with sulfuricacid. What term describes a reaction which gives out heat? The reaction of iron with steam is shown. 3Fe + 4H2O → Fe3O4 + 4H2 How does this equation show that iron gets oxidised? Rust contains hydrated iron(oxide. Describe and explain one method of preventing iron from rusting. 
0620_s20_qp_32
THEORY
2020
Paper 3, Variant 2
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Oxygen is produced by the decomposition of hydrogen peroxide. Manganese(oxide is the catalyst for this reaction. What is meant by the term catalyst ? A student measures the volume of oxygen produced at regular time intervals using the apparatus shown. Large lumps of manganese(oxide are used. aqueous hydrogen peroxide gas syringe manganese(oxide catalyst A graph of the results is shown. volume of oxygen produced / cm3 time / s What happens to the rate of this reaction as time increases? In your answer, explain why the rate changes in this way. The experiment is repeated using the same mass of manganese(oxide. Powdered manganese(oxide is used instead of large lumps. All other conditions stay the same. Sketch a graph on the axes in to show how the volume of oxygen changes with time. In terms of particles, explain what happens to the rate of this reaction when the temperature is increased. The equation for the decomposition of hydrogen peroxide is shown. 2H2O2→ 2H2O+ O225.0 cm3 of aqueous hydrogenperoxide forms 48.0 cm3 of oxygen at room temperature and pressure (r.t.p.). Calculate the concentration of aqueous hydrogenperoxide at the start of the experiment using the following steps. ● ● Calculate the number of moles of oxygen formed.  mol ● ● Deduce the number of moles of hydrogen peroxide that decomposed.  mol ● ● Calculate the concentration of hydrogen peroxide in mol / dm3.  mol / dm3  Oxygen can also be produced by the decomposition of potassiumchlorate(, KCl O3. The only products of this decomposition are potassiumchloride and oxygen. Write a chemical equation for this decomposition. 
0620_s20_qp_42
THEORY
2020
Paper 4, Variant 2
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