Chemistry Coursework Essay Example

Chemistry Coursework Essay Example Chemistry Coursework Essay Chemistry Coursework Essay The reactivity series is a chart showing the order that metals react with other substances. This reactivity series was determined by carrying out experiments to see how each metal reacts. The reactions are done with air, water and dilute acid.The reactivity series:Potassium (k)Sodium (Na)Calcium (Cl)Magnesium (Mg)Aluminum (Al)(Carbon)Zinc (Zn)Iron (Fe)Lead (Pb)(Hydrogen)Copper (Cu)Silver (Ag)Gold (Au)Platinum (Pt)Metals extracted by electrolysis.Metals extracted by using reduction with carbon (carbon monoxide)These metals dont react with water or acid.Exothermic and Endothermic reactions:In an exothermic reaction heat is given OUT. An exothermic reaction is one which gives out energy to the surroundings, usually in the form of heat and usually shown by a rise in temperature. For example burning fuels obviously gives out heat making it exothermic.In an endothermic reaction heat is taken IN. An endothermic reaction is one which takes in energy from the surroundings, usually in the form of heat and usually shown in a fall of temperature. For example dissolving certain salts in water.During a chemical reaction old bonds are broken and new ones are made.Energy must be supplied to break bonds so this is an ENDOTHERMIC process.Energy releasedNa Cl Na + ClStrong bond Bond brokenEnergy is released when new bonds are formed so this is an EXOTHERMIC process.Mg + O Mg O + energyIf the energy released in bond formation is greater than the energy used in breaking old bonds, the reaction is EXOTHERMIC.If the energy required to break old bonds is greater than the energy released when the bonds are formed, the reaction is ENDOTHERMIC.Enthalpy profilesENDOTHERMICExothermicTheoryThe reactivity of a metal is related to how easily it can lose its outer shell electronsM-2e MThe more reactive the metal he easier this process is so it takes less energy. All of the displacement reactions are exothermic reactions so the Energy going out is larger than the energy coming in. The enthalpy profiles show the energy coming in (1), the energy out (2) and how exothermic/endothermic the overall reaction was (2)-(1)=(3).The energy being taken in is the energy required to break the bonds + the energy required to do: M-2e M .The energy coming out is the energy from the forming bonds + energy from: Cu +2e Cu.Most of these energies stay the same because the metals are displacing copper. The only significant change as I add the different metals will be the energy it takes to do M-2e M . Therefore the most reactive metal will need less energy to remove electrons.Key Factors/VariablesKey factors or variables can be changed that would make a difference to the reactions or results taking place. These are:; Amount of copper sulphate solution-use more or less. It needs to be in a certain amount as it could either be too dangerous or not cause a good reaction; Moles of metal-this might change the speed of the reaction or the amount of heat given off.; Type of solution-using a different solution could make the reactions stronger or weaker.; Type of metal-using different types of metals could show more results.; Different concentration of solution (stronger/weaker); Whether it is stirred- could change the speed of the reactionPredictionI think that given the information I know I would guess that magnesium would let out the most thermal energy because it is the most reactive metal I am experimenting with. The higher the metal in the reactivity series the higher the amount of thermal energy given out.PreliminaryMethod:A 50th of a mole of magnesium, iron, lead and zinc was measured out. The temperature of the copper sulphate was taken before any experiments were started. Then 10cm3 of solution was put into 3 different test tubes and the metals were added. The concentrations were stirred and a thermometer was placed in each test tube and the highest temperature was taken and recorded. The experiment was repeated 2 more times so an average could be taken for accuracy.Fa ir TestTo make sure that the experiments done are fair these things need to be taken into consideration:; Same amount of moles of metal.; Same amount of concentration of copper sulphate.; Same amount of times stirred.; Same concentration (copper sulphate).; Same metals (zinc, magnesium, iron and lead); The temperature of the room where the experiments are taking place.; The starting temperature of the thermometers.Do more reactive metals give more exothermic reactions in their displacement reactions with copper sulphate solution less reactive metals?Aim: To investigate if the reactivity of a metal affects how exothermic its reaction with copper sulphate solution (displacement reaction).Apparatus; 12 boiling tubes; Scales; Spatula; Calculator; Powdered Lead (s), Magnesium (s), Zinc (s), Iron (s); 3 Thermometers; Copper sulphate (aq) solution.; Measuring cylinder.; Test tube rackMethod1/50th of a mole of each metal was measured out. 12 boiling tubes were put out in test tube racks eac h with 10cm3 of copper sulphate solution in. Before any of the experiments were taken out the temperature of the solutions were taken. Then 4.14g (1/50th of a mole) of lead were added to the copper sulphate solution. The solution was stirred 5 times. The highest temperature was taken. Then 0.48g (1/50th of a mole) of magnesium were added to the solution and stirred 5 times, the highest temperature was taken. Then 1.12g (1/50th of a mole) of iron were added and stirred 5 times, the highest temperature was taken. The same was done with 1.3g (1/50th of a mole) of zinc. All of the temperatures were recorded. All of the experiments were repeated two more times for accurate readings.Workings out:Lead: Iron:Mass number = 207 Mass number = 561/50th = 1?50 = 50 1/50th = 1?50 = 50207?50 = 4.14g 56?50 = 1.12gMagnesium: Zinc:Mass number = 24 Mass number = 651/50th = 1?50 = 50 1/50th = 1?50 = 5024?50 = 0.48g 65?50 = 1.3gResults:Lead:21 21 21 Starting temp22 25 23 Highest tempBoiling tube 1 Boi ling tube 2 Boiling tube 3Magnesium:21 21 21 Starting temp87 82 83 Highest tempBoiling tube 1 Boiling tube 2 Boiling tube 3Iron:21 22 21 Starting temp35 33 31 Highest tempBoiling tube 1 Boiling tube 2 Boiling tube 3Zinc:22 21 22 Starting temp56 55 58 Highest tempBoiling tube 1 Boiling tube 2 Boiling tube 3Results table:Start temperature?CTemperature after?CMetal123Avr?C123Avr?CMg21?C21?C21?C21?C87?C82?C83?C84?CPb21?C21?C21?C21?C22?C25?C23?C23?CFe21?C22?C21?C21?C35?C33?C31?C33?CZn22?C21?C22?C22?C56?C55?C58?C56?CChange of temperature?T = change in temperature?T = end of temperature start temperatureMg = 84-21 = ?T 63à ¯Ã‚ ¿Ã‚ ½cPb = 23 21 = ?T 2à ¯Ã‚ ¿Ã‚ ½cFe = 33 21 = ?T 12à ¯Ã‚ ¿Ã‚ ½cZn = 56 22 = ?T 34à ¯Ã‚ ¿Ã‚ ½cWorkings outMass of Mg = 0.48g à ¯Ã‚ ¿Ã‚ ½ 10g (mass of the copper sulphate) = 4.8gMass of Pb = 4.14g à ¯Ã‚ ¿Ã‚ ½ 10g (mass of the copper sulphate) = 41.4gMass of Zn = 1.3g à ¯Ã‚ ¿Ã‚ ½ 10g (mass of the copper sulphate) = 13.0gMass of Fe = 1.12g à ¯Ã‚ ¿Ã‚ ½ 10g (mass of the copper sulphate) = 11.2g?Q = m à ¯Ã‚ ¿Ã‚ ½ Cp à ¯Ã‚ ¿Ã‚ ½ ?TMg = 10.48g à ¯Ã‚ ¿Ã‚ ½ 4.2 à ¯Ã‚ ¿Ã‚ ½ 63à ¯Ã‚ ¿Ã‚ ½cPb = 14.14g à ¯Ã‚ ¿Ã‚ ½ 4.2 à ¯Ã‚ ¿Ã‚ ½ 2à ¯Ã‚ ¿Ã‚ ½cZn = 11.3g à ¯Ã‚ ¿Ã‚ ½ 4.2 à ¯Ã‚ ¿Ã‚ ½ 12à ¯Ã‚ ¿Ã‚ ½cFe = 11.12g à ¯Ã‚ ¿Ã‚ ½ 4.2 à ¯Ã‚ ¿Ã‚ ½ 34à ¯Ã‚ ¿Ã‚ ½cMetalQ (J)MgPbZnFe1270.08347.761856.4560.448AnalysisWhen doing my test there were some things that went wrong. When I poured in my metals, because I had already put the copper sulphate in the boiling tubes the metals stuck to the side, which may have ruined my results. If all of the metal was included in the experiment then a higher reading may have been taken. If I were to do this test again I would use a funnel to put the metals inside the boiling tubes or use bigger boiling tubes.The boiling tubes lose heat through the glass. To make it a fairer test next time I should use polystyrene or cotton wool to wrap around the test tube this way not much heat should escape.When doing my e xperiments I only repeated the tests 3 times to get a reading it would be better if I had dine the experiment about 5 times then I would have been able to get more of a accurate result.Luckily when I did my tests I didnt get any odd results. All of my results were about the same the only difference was a few degrees.