The energy produced of different alcohols.
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Planning My aim for this experiment is to see the energy produced of different alcohols. Variables involved: For this experiment I would expect to have 3 different variables, Independent, Dependent, and fixed variables, which all helps me to plan and explain the experiment thoroughly. The Independent variable (things you change), the thing that I will be changing in this experiment into the combustion of a range of alcohols, would be five different alcohols, Methanol, Ethanol, Propanol, Butanol, and Hexanol, which will help me to investigate combustion of different alcohols. I will measure these individual alcohols by mass which will be measured in grams, I'll be making two readings of each alcohol before the experiment and after, which would tell me the mass lost and how much heat in produces in 5 minutes. Dependent Variable (things that you measure) the things that I'll be measuring would be the temperature (oC) increase by every minute of each different alcohol being lit to heat the water in the copper calumeter, and the mass before and after the experiment of alcohols. Fixed Variables (Things that you keep the same) the things that I have chosen to keep the same in each individual experiment to keep it a fair test, is to keep the same amount of water being heated, the same copper calumeter (as it may very in conductivity), the height of the calumeter, and the same amount of time for each experiment. This would help me to compare and analyse the results of the individual experiments. Hypothesis: My prediction for this experiment on investigating the energy produced by different alcohols is that, the longer the hydrocarbons in the chain of the alcohols, the more heat it will produce. As the alcohols are being lit by the waxy splint that produces heat, it will also give out oxygen and water as well as heat energy to heat the water, which will crack the hydrocarbons into simpler molecules (smaller)
I will then light the sprit lamp with a wooden splint wearing my safety glasses, and making sure the tip of the flame reaches the calumeter flask at the same time will be starting the stop clock recording the temperature of the water every minute. I will then do the same thing for each alcohol and repetition, giving me the most reliable and accurate results. Looking at my preliminary results I decided to also change the time of when I will record the temperature gained by the water, from 2 minutes, to 1 minute, as the results I got in my preliminary results had a great change in temperature. This makes the experiment longer and harder as we only get one lesson to carry out the results and repetition of 5 different alcohols. When I record the readings of the temperature I will be plotting down 5 readings for each alcohol giving me enough results to carry out a graph. I will then repeat the experiment for each alcohol, which will give an average of the two, I can then draw a graph of all 5 alcohols showing the temperature gained each minute that I can compare to the each other helping me to explain the results. I will also work out how much heat went into the copper calumeter flask from the alcohol burning by using the following formula: Heat given out = mass of water x 4.2 x change in temperature The units I will be using for the formula are listed below: · Heat given out: Joule (J) · Mass of water: Grams (g) 1cm3 = 1 · Change in temperature oC I plan to record my results in the table seen below, which I also used in my preliminary work for each different alcohol. Temperature in oC Time (Min) Temperature 1st 2nd Results Average results Temp Gained 0 1 2 3 4 5 Mass before = 2nd results mass before = Mass after = 2ndresults mass after = Results Temperature of water heated by METHANOL sprit lamp.
The odd result of the Propanol alcohol could have been an anomalous result for a number of reasons. It could have been because the tip of the fame might have not been touching the bottom of the copper calumeter flask, making the alcohol produce less heat to the water in the calumeter flask. It could have also been because of the flame as it might have been too small, which might have also gave a low temperature reading to heat the 150ml of water. The procedure of the experiment was good enough of finding out the energy gained from the indivdual alcohols, but changes could have been made to make the reliability of the results more accurate. This could have been done by using a better and more accurate thermometer, such as an electric thermometer, which have gave me a much more pin point set of results. If I were to do this experiment again I would make a number of improvements or changes, one of my changes would have to be to use a Bunsen burner which would heat each alcohol and I could record its temperature gain every minute. This could be done by placing about 100ml of alcohol in a glass flask which would be heated with a Bunsen flame recording the results and comparing them to each other. I could also then measure the amount lost after recording the alcohol temperature after about 8 minutes, these results will be really high but we'll have a greater difference between each alcohol. Looking at the experiment I did I thought we could have extended the results we achieved by using different flame lengths, this would have told us how much the alcohol uses its energy when the flame is increased. I could have also changed the amount of water in the copper calumeter, or even change the metal of the calumeter to change the conductivity.
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