Aristo Book 5 experiment answer Essay

HKDSE CHEMISTRY A Modern View (Chemistry) investigate Workbook 5Suggested answersChapter 52 Importance of industrial processesChapter 53 Rate comparabilityExperiment 53.1 Determining the browse equation of a chemical re profession victimization method of initial deem (A microscale taste) 1Chapter 54 energizing energyExperiment 54.1 Determining the activation energy of a chemical reaction 3Chapter 55 Catalysis and industrial processesExperiment 55.1 offerfulvas the action of a atom smasher6Experiment 55.2 Investigating homogeneous catalysis8Experiment 55.3Investigating ways to stir the rate of a reaction with a suitable throttle 9Experiment 55.3 Sample laboratory report13Experiment 55.4Preparing ethyl alcohol by fermentation16Chapter 56 Industrial processesChapter 57 Green chemistry for industrial processesChapter 53Rate equationExperiment 53.1Determining the rate equation of a reaction using method of initial rate (A microscale experiment)7. and 11.(a) wellspring numb er12345678 telephone number of drops of 0.5 M Na2S2O3(aq)109876543 measure, t (s)14.215.817.820.423.828.635.747.6(s1)0.0700.0630.0560.0490.0420.0350.0280.02110. and 12.(a)Well number12345678Number of drops of 1.0 M H2SO4(aq)109876543Time, t (s)59.459.760.060.759.960.061.060.5(s1)0.0170.0170.0170.0160.0170.0170.0160.01711.(a)inversely(b)(c)112.(b)0(c)From the results in Table 53.2, the readings of sequence atomic number 18 close, indicating that the reaction is of zeroth order with respect to H+(aq).13.Rate = kS2O32(aq)14.S2O32(aq) + 2H+(aq) S(s) + SO2(g) + H2O(l)15.In this experiment, the time for the formation of a fixed, solely small agreeity of indissoluble sulphur precipitate is measured. The shorter the time, the fast is the reaction. It is assumed that the extent of reaction is still small when the time is recorded, so that the time recorded can be used as a measurement of initial rate of the reaction. Chapter 54Activation EnergyExperiment 54.1Determining the activation energy of a chemical reaction5.Temperature of the reaction mixture (C)1525354555Time for the appearance of gloomful blue colour (s)679(at 11C)232(at 27C)112(at 37C)80(at 43C)33(at 56C)6.(a)rate constant activation energy Universal gas constant temperature(b) record ()2.832.372.051.901.523.523.333.233.163.04(c)(d)2750(e)slope = 2750 =Ea = 2750 2.3 8.314 J mol1= 52 586 J mol1= 52.6 kJ mol17.Arrhenius equation log k = log A8.straight line9.S2O82(aq) + 2I(aq) 2SO42(aq) + I2(aq)10.To monitor the formation of iodine from the reaction of S2O82(aq) ions and I(aq) ions.11.When all S2O82(aq) ions have reacted, any iodine formed entrust turn the starch resoluteness swart blue. The time for this colour change is a measure of the rate of reaction shown in question 9. (Note The reaction rate is inversely proportional to the time taken for the starch closure to turn dark blue.)12.The amount of reactants used in each experiment may not be exactly the similar.There may be an error in me asurement or reading the temperatures from the thermometers.As the colour change of the ascendant mixture is not a sudden one, especially at low temperatures, there may be an error in recording the time of colour change.Chapter 55Catalysis and industrial processesExperiment 55.1Investigating the action of catalyst1.(b)No.5.(b)Time (s)102030405060Volume of O2(g) released (cm3), with the entree of 0.5 g MnO2(s) 306085959696Time (s)708090 vitamin C110120Volume of O2(g) released (cm3), with the addition of 0.5 g MnO2(s) 966.(b)Time (s)102030405060Volume of O2(g) released (cm3), with the addition of 1.5 g MnO2(s) 7090959696Time (s)708090100110120Volume of O2(g) released (cm3), with the addition of 1.5 g MnO2(s)8.9.Manganese(IV) oxideMnO2(s)10.2H2O2(aq) 2H2O(l) + O2(g)11.(a)The addition of manganese(IV) oxide greatly increases the rate of decomposition of hydrogen peroxide.(b)(i)The initial rate of reaction is higher.(ii)The total time of reaction is shorter. (Note increasing the amoun t of catalyst would increase the reaction rate.)(c)No.12.Add more H2O2(aq) to the reaction mixture, fast effervescence shows that manganese(IV) oxide has not been used up in the reaction. The catalytic property of manganese(IV) oxide is still present. Experiment 55.2Investigating homogeneous catalysis5.Mixture y.It has a characteristic sweet smell like certain glues or pillory polish removers.6.ethyl ethanoate concentrated sulphuric acid7.CH3COOH(l) + CH3CH2OH(l) CH3COOCH2CH3(l) + H2O(l)8.Homogeneous catalyst. This is because all species are in the same manikin in the reaction, i.e. the liquid phase.9.Sodium carbonate solution reacts with any unreacted ethanoic acid left in the reaction mixture. The loaded vinegar smell of ethanoic acid is thus removed. The salt atomic number 11 ethanoate formed has no smell. Besides, the ester is insoluble in water and floats on the water surface. This makes us easier to detect the smell of ester. Experiment 55.3Investigating ways to change t he rate of a reaction with a suitable catalyst1.ApparatusSafety spectaclesProtective glovesconic flask (100 cm3)5 measuring cylinders (10 cm3)Dropper stop watchBoiling furnishWhite tileChemicals ammonium ion peroxodisulphate solution (0.020 M)Potassium iodide solution (0.50 M)Sodium thiosulphate solution (0.010 M)0.2% starch solutionIron(II) chloride solution (0.010 M)Distilled water2.What you will keep constant(Controlled variable)What you will change(Independent variable)What you will measure(Dependent variable) raft of ammonium peroxodisulphate solutionvolume of potassium iodide solutionvolume of sodium thiosulphate solutionamount of 0.2% starch solutionwith or without using iron(II) solutionthe time for the appearance of the dark blue colour3.Figure 14.(1)Using a measuring cylinder, add 10 cm3 of ammonium peroxodisulphate solution to a conelike flask. (2)Using different measuring cylinders, add 5 cm3 of potassium iodide solution, 5 cm3 of sodium thiosulphate solution, 1cm3 of iron(II) chloride solution and 2.5 cm3 of starch solution to a boiling tube. (3)Pour the content in the boiling tube into the conical flask. (4)Immediately start the stopwatch.(5)When a dark blue colour of the starch-iodine multifactorial appears in the solution, stop the stopwatch. (6)Record the time for the appearance of the dark blue colour in Table 1. (7)Repeat stairs (1) to (6), but replace iron(II) chloride solution with 1 cm3 of distilled water.5.Risk assessment form6.Time for the appearance of the dark blue colourWith Fe2+(aq) ions (as a catalyst) added59 sWithout any catalyst added3 mins and 52 sTable 17.The reaction involves the collision of two negatively charged ions, S2O82(aq) ions and I(aq) ions, which actually fight off each other.8.S2O82(aq) + 2Fe2+(aq) 2SO42(aq) + 2Fe3+(aq)2Fe3+(aq) + 2I(aq) 2Fe2+(aq) + I2(aq)9.Referring to the two equations in question 8, the S2O82(aq) ions oxidize the Fe2+(aq) ions to Fe3+(aq) ions. At the same time, the S2O82(aq) ions are re duced to SO42(aq) ions. The Fe3+(aq) ions are strong oxidizing agents that oxidize I(aq) ions to I2(aq). At the same time, Fe3+(aq) ions are reduced back to Fe2+(aq) ions (i.e. the catalyst is regenerated). some(prenominal) the equations shown in question 8 involve the collision between positive and negative ions. This will be much more likely to be successfulthan the collision between two negative ions in the uncatalysed reaction. Thus, the activation energy of this pathway will be lower and the reaction rate will alike be higher.10.The chemical reaction can be speeded up by the addition of iron(II) ions, which act as a homogeneous catalyst of this reaction.11.It can be regenerated after the reaction. OR It is specific in action. OR A small amount of catalyst is usually enough for the catalytic action.12.Homogeneous catalyst is one which has the same phase as the reactants and products. Sample laboratory reportTitle Investigating ways to change the rate of a reaction with a suitab le catalystObjectiveTo design and carry out an experiment to investigate ways to change the rate of a reaction by the use of a suitable catalyst.Apparatus and materialsSafety spectaclesProtective glovesConical flask (100 cm3)5 measuring cylinders (10 cm3)DropperStopwatchBoiling tubeWhite tileAmmonium peroxodisulphate solution (0.020 M)Potassium iodide solution (0.50 M)Sodium thiosulphate solution (0.010 M)0.2% starch solutionIron(II) chloride solution (0.010 M)Distilled waterChemical reactions involvedS2O82(aq) + 2Fe2+(aq) 2SO42(aq) + 2Fe3+(aq)2Fe3+(aq) + 2I(aq) 2Fe2+(aq) + I2(aq)Procedure1.Using a measuring cylinder, 10 cm3 of ammonium peroxodisulphate solution was added to a conical flask. 2.Using different measuring cylinders, 5 cm3 of potassium iodide solution, 5 cm3 of sodium thiosulphate solution, 1 cm3 of iron(II) chloride solution and 2.5 cm3 of starch solution were added to a boiling tube. 3.The contents in the boiling tube were poured into the conical flask. 4.The stopw atch was started immediately.5.When a dark blue colour of the starch-iodine complex appeared in the solution, the stopwatch was stopped. 6.The time for the appearance of the dark blue colour was recorded in Table 1. 7.Steps (1) to (6) were repeated, but iron(II) chloride solution was replaced with 1 cm3 of distilled water.ResultsTime for the appearance of the dark blue colourWith Fe2+(aq) ions (as a catalyst) added59 sWithout any catalyst added3 mins and 52 sTable 1After mixing all the chemicals in the conical flask, the reaction mixture with Fe2+(aq) ions will take a shorter time for the dark blue colour to appear.depth psychology1. In the absence of Fe2+(aq) ions, the reaction between S2O82(aq) ions and I(aq) ions is slow. As both reactant ions are negatively charged, they lean to repel each other. However, when Fe2+(aq) ions are added, thereaction becomes faster. Fe2+(aq) ions have the same phase (i.e. aqueous phase) as the reactants and products, so they are homogeneous catalys t of this reaction. 2. Fe2+(aq) ions is a reducing agent which can reduce S2O82(aq) ions to SO42(aq) ions. The Fe3+(aq) ions formed act as an oxidizing agent, which oxidize I(aq) ions to I2(aq) ions and regenerate Fe2+(aq) ions again. Being a catalyst, Fe2+(aq) ions are not consumed in the catalytic process.Discussion1.Either Fe2+(aq) ions are Fe3+(aq) ions is a good choice of catalyst for this reaction because the interconversion between Fe2+ and Fe3+ facilitates the reaction between S2O82(aq) ions and I(aq) ions to occur. 2.The catalytic property of Fe2+(aq) ions may be due to the fact that it is easier for the negatively charged S2O82(aq) ions to appeal the positively charged Fe2+(aq) ions. The same is true when the positively charged Fe3+(aq) ions formed can approach the negatively charged I(aq) ions easier. 3.The experiment is just a simple test tube experiment but the result (colour change) is quite obvious and easy to detect.ConclusionThe chemical reaction can be speeded up by the addition of Fe2+(aq) ions, which act as a homogeneous catalyst of this reaction.Answers to questions for further thought11.It can be regenerated after the reaction. OR It is specific in action. OR A small amount of catalyst is usually enough for the catalytic action.12.Homogeneous catalyst is one which has the same phase as the reactants and products. Experiment 55.4Preparing ethanol by fermentation3.(b)Glucose solutionwith yeastGlucose solutionwithout yeastAppearance of the glucose solutiona blanch brown faulta clear solutionObservations in the limewaterclear and neutralclear and colourless6.(d)Acidified potassium dichromate solution changes colour from orange to green.(f)No colour change for the acidified potassium dichromate solution.7.Glucose solutionwith yeastGlucose solutionwithout yeastAppearance of the glucose solutioncloudy a pale brown suspensionclear, no visible changeObservations in the limewatermilkyremains clear and colourlessSmell of the glucose solutiona sm ell of alcoholno characteristic smell8.catalyst9.ethanol carbon dioxide10.The solution turns milky. It indicates that carbon dioxide is produced during fermentation.11.In the heading of yeast, glucose is converted to ethanol. The presence of ethanol is indicated by the colour change of the reaction with acidified potassium dichromate solution. fermentation alcohol is a reducing agent. It reduces dichromate ions to chromium(III) ions.