Chemistry Course Work: Combustion of Alcohols
CHEMISTRY COURSE WORK:
COMBUESTION OF ALCOHOLS
AIM:
My main aim in this assignment is to investigate the combustion of at least five alcohols:
Ethanol
Propan-1-ol
Butan-1-ol
Pentan-1-ol
Hexan-1-ol
In this investigation we will also concentrate on how much energy is exerted when burning these alcohols we will also compare the Molar Heat of Combustion.
Alcohols are also known as "A series of organic homologous compounds with a general formula 'Cn H2n + 1 OH' "
Alcohols also burn in air where they react with Oxygen (O) to form the products of Water (H20) and Carbon Dioxide (Co2).
"Cn H2n + 1OH + (n+n/2)-1O2 ? nH2O + nCO2"
The reaction that takes place when alcohols are burnt is 'Exothermic' as heat is being given out; also the Reactant energy is higher than that of the Product.
APPARATUS:
Copper Can, (Calorimeter)
Spirit Burner,
Stand, Boss and Clamp with Wide Jaws,
Measuring Cylinder (100 cm3),
Thermometer (-100c to +1100c),
Balance,
Spirits: Ethanol, Propan-1-ol, Butan-1-ol, Pentan-1-ol,
Hexan-1-ol,
100 cm3 of Water (H2O).
Weighing scale (g)
PLANNING:
To actually help me make a proper plan and assessment of this investigation I will need to research mainly up on 'Combustion of Alcohols' and matters relating to it.
The data obtained and collected shall hopefully help me make a sound and stable prediction; this can also assist me in making a simple, fair and safe test. Most of the aid will also come from the 'Preliminary Work' and 'Experiment' in which I will have the opportunity to get a better understanding of the aim in this experiment.
The preliminary experiments that will be carried out will mainly involve us comparing two types of spirits being: Methylated Spirits, and Propanone.
HYPOTHESIS:
Alcohols differ from other organic compounds as their molecules are based on chains of Carbon atoms.
Alcohol molecules contain 1 oxygen atom that is joined to a carbon atom; these two atoms are joined simply by a single bond.
The oxygen in the Alcohol is also joined to a hydrogen atom thus also to a carbon atom (C-OH). Names such as 'Propan-1-ol', which end in '-1-ol', refer to the position of the -OH group on the carbon chain.
In this experiment my Hypothesis is that the more carbon atoms in an alcohol more the heat of Combustion is produced.
The Molar Heat of Combustion produced will vary to the amount of Oxygen present. When organic compounds are burnt they produce CO2 and H2O.
Heat
Alcohol + Carbon Dioxide + Water Vapour
Excess Air
PREDICTION:
The heat produced per mole of alcohol molecules will be proportional to the number of carbons in the alcohol molecule.
Thus for this investigation I predict that 'Hexan-1-ol' which contains 6 Carbon Atoms in its structure there fore it should produce the greatest heat loss, as more energy is required to brake the bonds. The Chemical Formulas for the five alcohols that we will use in this experiment are listed bellow.
Hexan-1-ol = C6H13OH
Pentan-1-ol = C5H11OH
Butan-1-ol = C4H9OH
Propan-1-ol = C3H7OH
Ethanol = C2H5OH
From the above list as you go down the order the Carbon Atoms in each Alcohol decrease, as you also go down the list I believe that this would be the order (Highest heat produced to lowest heat produced) there fore I predict that Hexan-1-ol and Pentan-1-ol should relatively have the highest heat loss and rise in temperature.
As the more bonds holding the Carbon, Oxygen and Hydrogen atoms together more the energy required to break these bonds.
And of the 5 alcohols that we will be using, 'Hexan-1-ol' has the greatest number of bonds in its structural formula
The heat produced per mole of alcohol molecules will be proportional to the number of carbons in the alcohol molecule.
I predict that branched alcohol molecules will give out more heat than isomers with straight chains because branched alcohol molecules have lower boiling points so they vaporise more easily at room temperature and are likely to be more inflammable and having lower flash points.
SCIENCETIFIC EXPLANATION:
Alcohols are similar to 'Alkanes' and 'Alkenes', as alcohols are a family of related compounds. These are also part of the Homologous series as each member of the series has the O-H group in its structure.
The formula for Alcohol is 'CnH2n + 1OH'
When Alcohols are burnt the number of Carbon a certain alcohol contains will relate to the amount of heat that is given out, this is known as the 'Enthalpy of Combustion'.
Enthalpy is defined as the energy of reaction, or the heat energy associated with a chemical change.
Combustion is the process in which bonds are broken. As heat is being given out the alcohols should have an exothermic reaction as heat is being exerted. When heat is given out the bonds of an alcohol are being broken this process is 'Endothermic' whilst the making of bonds is 'Exothermic'.
The Product in an Exothermic Reaction contains a lower energy level than that of the Reactants. Energy given out which in this case is transferred as Heat is given out when bonds are being formed between the water and Carbon Dioxide molecules (Co2).
A complete Combustion of an Alcohol is when the Alcohol reacts with Oxygen to form Water and Carbon Dioxide:
"Cn H2n + 1OH + (n+n/2)-1O2? nH2O + nCO2"
The molecular structure in this reaction is:
"H H || H - C - C - O- H + 3[O=O] ? 1/2[O=C=O] + 3[H-O-H] | | H H"
The above reaction is Exothermic as the 'Energy' used to break the bonds is given off or lost as 'Heat'.
'For any reaction carried out directly at a constant pressure, the heat flow is exactly equal to the difference between enthalpy of products and that of the reactants'
Bond formed in an Exothermic Reaction is forces attractions between the atom and ions in a substance, these types of attractions or bonds can only be:
Covalent Bond- These types of Bonds consist of atoms sharing electrons with other atoms in which both atoms will have a full outer shell, thus in these types of bonds provide 1 extra shared electron for each atom.
Ionic Bond- Atoms that are held together by Ionic Bond Lose or gain electrons to form charged particles (ions). In this bond electrons are transferred from 1 ion to another thus being an electrostatic force between the ions.
Longer the Structural Formula of an alcohol more the energy required to break its bonds, also the number of carbon, oxygen and hydrogen atoms in an alcohol will determine the energy required to break its bonds.
From the range of alcohols that we will be using 'Hexan-1-ol' has the highest number of Carbon, Oxygen and Hydrogen (C6H13OH) atoms present, than Ethanol (C2H5OH) thus the energy required to break the bonds present in 'Hexan-1-ol' will be more than that of 'Ethanol' there fore this will result in the energy produced by 'Hexan-1-ol' will be greater than that of ...
This is a preview of the whole essay
Longer the Structural Formula of an alcohol more the energy required to break its bonds, also the number of carbon, oxygen and hydrogen atoms in an alcohol will determine the energy required to break its bonds.
From the range of alcohols that we will be using 'Hexan-1-ol' has the highest number of Carbon, Oxygen and Hydrogen (C6H13OH) atoms present, than Ethanol (C2H5OH) thus the energy required to break the bonds present in 'Hexan-1-ol' will be more than that of 'Ethanol' there fore this will result in the energy produced by 'Hexan-1-ol' will be greater than that of 'Ethanol'.
VARIABLES:
This experiment also contains variables that must be controlled in order to validate this experiment; these Variables are also factors that can affect this experiment.
VARIABLES:
Type of Alcohol,
Temperature,
FIXED VARIABLES:
Apparatus,
Mass of Water,
Time,
Height of Calorimeter,
Type of Can (Copper Can),
PRELIMENARY EXPERIMENT:
The preliminary experiment that was carried out should give us the opportunity to familiarise our selves with the basis of the experiment
The aim of this preliminary experiment was to compare the combustion of 'Methylated Spirit' and 'Propanone' as fuels.
During this experiment we used the following apparatus and materials:
Copper Can,
Spirit Burner,
Stand, Boss and clamp with wide Jaws,
Measuring Cylinder 100 cm3,
Thermometer -10oC to + 110oC,
Balance,
Methylated,
Propanone.
Bellow the procedure that we followed in line to conduct this experiment:
PRELIMENARY METHOD:
Use a measuring cylinder to pour 100cm3 of water into the copper,
Measure the temperature of the water,
Half fill a spirit burner with Methylated spirits and weigh it.
Clamp the copper can so that the bottom of the can remains 5 cm above the wick of the spirit burner,
Weigh the spirit that will be used,
Light the Spirit Burner and stir the water with the thermometer,
When the temperature of water reaches 40oC then that of the starting temperature extinguish the spirit lamp (Do not allow the wick to smoulder).
Reweigh the spirit burner as quickly as possible.
Repeat the above steps with a fresh supply of water and spirit burner containing Propanone; make sure the size of flame is about the same.
PRELIMENARY RESULTS:
Methylated Spirit:
Volume of Water Burnt= 100cm3C Starting Temperature of Water= 28oCFinal Temperature of Water= 51oCRise in Temperature= 24oCMass of Ethanol before burning= 211.65 gMass of Ethanol after Burning= 210.46 gMass of Ethanol spirit Burnt= 1.19 g
Methylated Spirit:
Mass of Methylated spirit burnt = 1.19g
Change in Temperature (?T) = 24oC
Heat Produced (MXSX?T) = 100 X 4.2 X 24= 10080J
.19g of ethanol produce 10080J of energy
M.MM (Mass/Molar Mass) of Ethanol (C2H5OH) = 46
Mass/Molar Mass = Moles = 1.19g/46= 0.025869565 moles
0.025869565 moles produce 10080J.
mole = 10080/0.025869565= 389647.0621J (Ans/1000)= 38.9KJ
Heat of Combustion of Ethanol = 38.9KJ
Propanone:
Volume of Water= 100cm3CStarting Temperature of Water=22 oCFinal Temperature of Water= 45 oC Rise in Temperature= 23 oC Mass of Propanone before burning = 173.72gMass of Propanone after burning= 172.23gMass of Propanone burnt= 1.49g
Propanone:
Mass of Propanone burnt = 1.49g
Change in Temperature (?T) = 23 oC
Heat Produced (MXSX?T) = 100 X 4.2 X 23= 9660J
.49g of Propanone produce 9660J of energy
M.MM (Mass/Molar Mass) of Propanone (C3H7OH) = 60
Mass/Molar Mass = Moles = 1.49g/60= 0.024833333 moles
0.024833333 moles produce 9660J
mole = 9660/0.024833333= 388993.2938J (Ans/1000) = 388.9KJ
Heat of Combustion of Propanone = 388.9KJ
Analysis of Preliminary Results:
From the above results you can tell that the heat of combustion of Propanone is 388.9KJ and the heated of combustion in Methylated Spirits 38.9KJ from this data not only does it back up my Hypothesis that the more number of carbons in a spirit (Alcohol) the more heat of combustion which should results in a higher temperature increase for the higher amount of energy that was exerted to break the bonds of Propanone (C3H7OH) which are much stronger than that of the Methylated Spirits (C2H5OH) thus resulting in the higher heat of combustion for Propanone.
This also backs up my prediction that alcohols with the more bonds holding the Carbon, Oxygen and Hydrogen atoms together more the energy required to break the bonds which was also proven by the Preliminary Work and results that were obtained.
This Preliminary Work and Experiment that I carried out also gave me a chance to be more prepared and when carrying out my actual experiment.
FAIR TEST:
If the above Fixed Variables are not kept the same this will not be fair or valid experiment. To keep this experiment valid, I need to make sure that
When measuring the weight of the alcohol after it was burnt that the units, which I'l be using, are the same through out the experiment.
I will also need to ensure that the weighing balance and any other equipment are in good working other, and also that none of the equipment, which I'll be using, is faulty or this experiment will not be successful.
When experimenting with a new alcohol I will need to make sure that the initial temperature on the thermostat is at room temperature (20oC - 25o C) or that the initial temperature stays the same throughout the experiment. One very important factor is the condition in which the experiment is conducted under, to validate the experiment I will also need to ensure that the conditions are the same throughout.
The distance between the 'Calorimeter' and the spirit lamps need to be the same without compromising the experiment as the distance between the flame and the copper can is not kept the same the temperature readings will not be valid, this is why the distance between the Calorimeter and the Spirit lamp need to remain 5 cm throughout.
The Time Span at which we observe and record the change in temperature needs to be the same, therefore I have decided to record the temperature over 5 minutes and recorded the data at every 30 second interval during the 5 minute time span.
During this experiment the volume of water that will be used for every alcohol should remain the same and when weighing the Spirit Burner I need to ensure not only that the data is recorded but that that I weigh the mass of the spirit burner before the experiment and after the experiment using the same units in this case grams. One main procedure that I took in the preliminary experiment was to place a hard board draught excluder around the spirit burner and the experiment so that no excess air can reach or disturb the wick of the spirit burner that would render the validity of this investigation and experiment and also reduce the amount of heat loss.
SAFETY:
Thus this experiment may seem vary simple and straight forward, this experiment also its own hazards and measures must also be taken when conducting this experiment that no one is hurt or any damage is caused as we will be handling glass in which the spirit burner is found in.
As we will be handling Alcohols which are flammable I need to ensure that I don't accidentally drop the spirit burner as it is made up of glass and if broken the alcohol could pour and cause a lot of damages and also could easily catch a fire this is why I will need to be very gentle and conscious when handling it and also ensure that I am wearing a 'Lab Coat' so that my clothes are not damaged or any of the alcohol is spilled on it as it could also again catch fire and cause severe injuries.
In the event of an accident I will require to contact a teacher or who ever is in charge before I can continue with my experiment.
The Glass bottle for the spirits which is made up of glass isn't the only equipment which can be fragile, as also the thermometer can easily be broken especially when stirring the water using the Thermometer, to avoid breaking the equipment I have decided that when conducting the actual experiment I shall not stir the water in the 'Calorimeter' With the 'Lab Coat' I will also need to ware Goggles for eye protection in the case of glass breaking to ensure that none of the glass part go into my eye and cause any other injury
PLANNED METHOD:
During this experiment it will literally be impossible for me to control the temperature of the water over the 5 minutes in which its temperature will be taken as it will vary for every alcohol that will be used, but I can reduce the amount of heat loss from the spirit burner by placing a hard board draught excluder around the experiment.
During my Preliminary Work there were certain problems that I had come across such as 'Heat Loss', to avoid these problems again in the actual experiment I have taken certain measures, which hopefully will help me in obtaining sound and reliable data.
As stated earlier in this experiment I will be using the following alcohols:
Hexan-1-ol (C6H13OH)
Pentan-1-ol (C5H11OH)
Butan-1-ol (C4H9OH)
Propan-1-ol (C3H7OH)
Ethanol (C2H5OH)
If I can at the end of my experiment after taking one set of readings for every alcohol, I shall try to take repeat readings for at least 1 alcohol if not for all.
Whilst carrying out the Preliminary Work I did not time the experiment though this experiment will be timed, after a certain amount of time I shall stop taking readings for one type of alcohol and change to another thus I decided the time span at which I shall stop taking the readings for every range of alcohol will be 5 minutes. I will a
APPARATUS
Copper Can, (Calorimeter)
Spirit Burner,
Stand, Boss and Clamp with Wide Jaws,
Measuring Cylinder (100 cm3),
Thermometer (-100c to +1100c),
Spirits:
Ethanol, Propan-1-ol, Butan-1-ol, Pentan-1-ol,
Hexan-1-ol,
100 cm3 of Water (H2O),
Weighing scale (g),
Stop Watch,
Hard Board Draught Excluder,
Bellow is a step-by-step procedure of what I did in the experiment:
I firstly begun by collecting the required apparatus and setting it out for the experiment,
I then measured 100 cm3 of water in the Measuring Cylinder from which I then poured into the Calorimeter,
Then took the alcohol which I'd be using and weighed the initial mass
in grams and took down the data,
I also then took the initial temperature of the water and wrote down the result,
Later I clamped the Calorimeter and made certain that the distance between the Wick of the Spirit Burner was 5 cm from the Calorimeter,
I then lighted the spirit and at 30 seconds intervals for 5 minutes I took the temperature of the water,
After taking the temperature for 5 minutes I then extinguished the spirit lamp,
Afterwards I reweighed the alcohol, and noted down the final mass,
After this I repeated the above steps with a fresh supply of water and a different type of alcohol.
56°31°Heat of Combustion:
Ethanol,
Mass of Ethanol burnt = 1.5g
Change in Temperature (?T) = 25 oC
Heat Produced (MXSX?T) = 100 X 4.2 X 25= 10500J
.5g of Ethanol produce 10500J of energy
M.MM (Mass/Molar Mass) of Ethanol (C2H5OH) = 46
Mass/Molar Mass = Moles = 1.5g/25= 0.06
0.06 produce 10500J
mole = 10500/0.006=1750000J (Ans/1000) = 1750KJ
Heat of Combustion of Ethanol = 1750KJ
Moles of Ethanol Burnt (n. M/MM) = 1.5/46 = 0.003
Propan-1-ol,
Mass of Propanol burnt = -0.1g
Change in Temperature (?T) = 26oC
Heat Produced (MXSX?T) = 100 X 4.2 X 26= 10920J
-0.1g of Propanol produce 10920J of energy
M.MM (Mass/Molar Mass) of Propanol (C3H7OH) = 60
Mass/Molar Mass = Moles = -0.1/26 = -3.846153246
-3.846153846 produce 10920J
mole produce= 10920/-3.846153846 = -2,839.2J (Ans/1000) = -2839.2KJ
Heat of Combustion of Propanol = 2839.2KJ
Moles of Propanol Burnt (n. M/MM) = -0.1/60= -1.6
Butan-1-ol,
Mass of Butanol burnt = 1.1g
Change in Temperature (?T) = 27oC
Heat Produced (MXSX?T) = 100 X 4.2 X 27=11340J
.1g of Butanol produce 11.340J of energy
M.MM (Mass/Molar Mass) of Butanol (C4H9OH) = 74
Mass/Molar Mass = Moles = 1.1/27 = 0.04074074
0.04074074 produce 11340J
mole produce = 11340/0.04074074 = 278.345.4596J
(Ans/1000) =278.3454596KJ
Heat of Combustion of Butanol = 278.34KJ
Moles of Butanol Burnt (n. M/MM) =1.1/74 = 0.14
Pentan-1-ol,
Mass of Pentanol burnt = 0.3g
Change in Temperature (?T) = 18oC
Heat Produced (MXSX?T) = 100 X 4.2 X 18= 7560J
0.3g of Pentanol produce 7560J of energy
M.MM (Mass/Molar Mass) of Pentanol (C5H11OH) = 88
Mass/Molar Mass = Moles = 0.3/18 = 0.016666666
0.016666666 produce 7560J
mole produce = 7560/0.016666666 = 453.600.0181J
(Ans/1000) =453.6000181KJ
Heat of Combustion of Pentanol = 453.6 KJ
Moles of Pentanol Burnt (n. M/MM) = 0.3/88 = 3.40
Hexan-1-ol,
Mass of Hexanol burnt = 0.6g
Change in Temperature (?T) = 27 oC
Heat Produced (MXSX?T) = 100 X 4.2 X 27=11340J
0.6 of Hexanol produce 11340J of energy
M.MM (Mass/Molar Mass) of Hexanol (C6H13OH) = 102
Mass/Molar Mass = Moles = 0.6/27 = 0.022222222
0.022222222 produce 11340J
mole produce = 11340/0.022222222= 510.300.0051J
(Ans/1000) = 510.3000051KJ
Heat of Combustion of Hexanol = 510.30KJ
Moles of Hexanol Burnt (n. M/MM) = 0.6/102= 5.8
Repeat of Hexan-1-ol,
Mass of Hexanol burnt = 0.6g
Change in Temperature (?T) = 31 oC
Heat Produced (MXSX?T) = 100 X 4.2 X 31=13020J
0.6 of Hexanol produce 13020J of energy
M.MM (Mass/Molar Mass) of Hexanol (C6H13OH) = 102
Mass/Molar Mass = Moles = 0.6/31 = 0.019354838
0.019354838 produce 13020J
mole produce = 13020/0.019354838= 672.700.0247J
(Ans/1000) = 672.7000247KJ
Heat of Combustion of Hexanol = 672.70KJ
Moles of Hexanol Burnt (n. M/MM) = 0.6/102= 5.8
ANALYSIS:
When obtaining the 'Heat of Combustion' for each alcohol I also worked out the amount of energy involved by using a simple formula:
Energy evolved = Mass x Rise in temperature x SHC
The graph shows a Line graph of the 'Heat of Combustion' for every alcohol, on the graph there are two lines, the first line in pencil shows the Heat of Combustion and the second line represents a line of best fit.
From the data obtained and also by looking at the graph it shows that
Propan-1-ol has the highest Heat Of Combustion that totally contradicts what I have predicted in my Hypothesis there fore leading me to believe that my results are totally unreliable.
Looking at the graph you can see that Butan-1-ol has the lowest Heat of Combustion, which again shows how unreliable the results are because in my Hypothesis I had predicted that the Alcohol with the most bonds and Carbon atoms in its structure will have the highest Heat of Combustion in this case Butan-1-ol and Hexan-1-ol should respectively have the Highest Heat of Combustion instead the graph shows that Propan-1-ol and Ethan-1-ol have the highest heat of combustion even though they have lees bonds and a shorter structural formula with the relatively the lowest number of Carbons.
I believe that when I conducted this experiment despite the preparation that I took still there were mistakes and errors or my prediction was proven wrong, as the alcohol with the shortest molecular structure seemed to produce more heat.
From the results that I obtained the one result, which merely proves that my Hypothesis was right is the Rise in Temperature as the alcohols with the highest number of Carbons present being Hexan-1-olhad the highest change from the initial to final temperature.
EVALUTAION:
The resutls obtained turned out to be anomalous and are very confusing. Heat of combustion results went from high to low starting with Ethanol which has the least amount of bonds to Heaxanol which has the most for moles burnt the reuslts went from low to high then went back down again (pentanol) and back up (heaxanol).
A downwards curve was produced for the neat of combustion and a downards curve with a hill and the curve reproducing was the line sustained for moles burnt.
The proceedure to followed for this experiemnt seemed fine but obviously was not. I can only come to the conclusion that human errors and carelesness occured.
I did not repeat the experiemnt to find an average due tio there not being any time to do so and also it would take a lot of attention and alertness to achieve accurate results.
The alcohols did not weight the same due to lack of them. I blelieve this is the variable which greatly affect my results. If the mass for the alcohol was all the same results would be clearer.
The amount of water in the copper may have been different for each aslchol. The temperature at the beginning of the experiemnt may have been for each alcohol especailly if as soon as I finished one test I would quickly move on to the other.
Even with a card board box to block the draught the flame still increased and at one point when I was testing the pentanol and alcohols beyond I was able to control the flame.
The procedure for this experiemnt was straight forward. it did not really give a detailed explanation of what you should do I.e make sure the masses weigh the same flame was the same etc. The procedure lacked common sense details whcih I would correct next time. So the procedure from the beginning was not suitbale to porduce decnt reuslts meaning the porcedure was not a good one.The Combustion the alcohols was not finished productiing Carbon Monoxide gas, Carbon soot, excreting little exothermic energy. A good supply of air is necessary for complete combustion, so there must not be any formof air, flowing around the equipment.
The results obtained were unreilable and anomolous and did not support my prediction.
If I could make improvements I would. Use a wider mixture of alchols so I could get a 'CHAIN OF RESULTS' and support a frim conclusion
I would have aslo used a newer scales as this could have had an affect on the weight of the mass.
I would have complelely covered the falme as I notcie the birds eye view section of the flame could be seen respectivly and this could have effected my reuslts.
The clamp was touching the copper can.This would have some of the heat could have been transferred into the clamp and stand, causing more heat loss form the experiment. In order for improve ont his I would have to insulate the can and the clamps, completely exclude all draughts use a better conductor other than water to heat, and use a thinner can, made of a better heat conducting material.
Heat Could not have been absorbed by the copper, as convection currents will have absorbed heat air up and round the apparatus without it being measured. This error will give a lower reading than expected. To improve upon this will better draught shielding
to stop air escaping.
Factors:
) Energy given off through sound and light.
2) Heat conducted and convected away through the air.
3) Radiation of heat out into the atmosphere.
4) The fact that the beaker gets hot.
5) The rubber clamp transferred heat way.
6) Heat may be taken away through guts of wind.
7) The fact that at higher temperatures, heat is lost faster to the air and out of the beaker, due to the bigger heat difference, making the higher temperatures more inaccurate, and making a shallower gradient on the graph.
8) By incomplete combustion
9) The amount of energy you give the alcohol originally.
0) The availability of alcohol for the wick to burn, if not enough then the wick would burn not the alcohol that would give an inaccurate result.
1) Evaporation of water so there will be less water to heat, making the water hotter.
2) The size of the wick.
3) Not all of the water was the same temperature.
4) The flame size changed due to the type of alcohol; hence it was a different distance away from the beaker each time.
Reasons 1-10 would cause the reading to decrease whilst Reasons 11-14 would cause the reading to increase
Whilst conducting this experiment controlling the heat loss was very hard if not impossible, as heat is an unreliable way of transferring energy without any loss. One limiting factor in this experiment I feel was convection of air and water.
Thus in this experiment a small amount of water would have evaporated as it is being heated, there fore the water's temperature reading would have been altered. One other down fall in my experiment was that I had not been able to conduct any repeat experiments for all the alcohol instead of just 'Hean-1-ol', this was due to the miss timing of my experiment, thus with these reading not allowing me to draw up a firm and accurate 'Conclusion'.
In this experiment some of the equipment that we had used at times could have been a liability to the experiment, such as the 'Calorimeter' that we had used it would not have transferred all the heat across, as some of the heat would have been lost heating up the Copper Can (Calorimeter).
Despite having taken certain measures to stop the reduce the loss of Heat, I had only covered the sides of the Spirit Burner leaving the top opened, meaning there was still huge amounts of heat that could have escaped.
This experiment could have been improved in many ways for instance using a wider range of alcohols such as 'Methanol'.
The more range of Alcohols should give a better graph and a wider range of results to support a firm conclusion. If I were to repeat this experiment I would concentrate more in finding ways to reduce Heat Lost and insuring that all of the above factors and possible sources of error are counteracted and controlled, so that hopefully no anomalous readings or unreliable data would be collected. I feel that in this experiment we should have heated different substances other than water.
Evaluation
Overall my results for my experiment were reliable. The readings increased as the length increased and current. The readings producing roughly straight line showing my results were reliable.
The procedure use to conduct the experiment appeared to work well. I eventually took out the reisistor from the experiment as when I did my pilot experiment it was not needed. My results were not 'dented' in any way by it's absecne.
Looking at the results obtained they seem to be valid. When I was testing the resistance of a wire when the current was at 0.1, the resistance was increasing roughly by 0.3 which was excellent.
altough on the 50cm reading the reuslt did not follow the pattern of going down in intervals of 0.3 but 0.4
It could be that I did not accurately place the point on to the wire, it could be the point was not place on the 50cm mark or it could be the current may have been tampered with.
The rest of the currents did create a pattern of the way the resistance increased but then at the same time some results were out of place. It could be for the reasons above.
0.2A made the resistance go down (roughly) by 0.45 but not all. the 20cm length went down by 0.55A. 0.5A made the first to length move down by 0.38 and the last three by 0.36.
The results did a produce a sraight line but it does bend but not very much. but anomalous results still are produced.
The procedure is suitiable to use. In my opinion it is possible to get good concrete results as I. I think that the way the pointer was placed is what may have cost my anomoulas result in places.
A few changes can be made to make this expeiment to be more accurate and reliable and that is to use equipment to measure out the length of the wire rather then by hand.as our vision is not good enough to get the measurement 100% right also when the pointer is placed on the wire it could have jerked slightly away from the measurement without notice.
My resuls in my opinion are anomonous or at least some even tough I did the experiment again I reproduced the same results but still the prefect sraight line waas not produced.
I look at the results from scientific point of view: if you produce the same results twice that means the results are reliable.
The results do support a firm conculsion and my prediction as the resistance increases when the length does and the fact a straight line is made and the line goes through the original means the length and resistance are poportional to each other.
To make improvements to my experiment I would use newer equipment especially the voltmeter as It did tend to flicker to and fro numbers when trying to find the voltage.
I could next time use a ohmmeter to produce the exact resistance
I would find a mechanism to locate the measurement of the wire as the rulers used are
not exact, and it is difficult to get an accurate reading of length by eye vision, as
the wire might not be completely straight, it may be of different thicknesses
throughout the length.
I would also investigate other factors, such as temperature, voltage and
current, and see how these effect the resistance. I would also do the
experiments under different conditions such as temperature and pressure to see
if it makes any difference to resistance.
