• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

An investigation into the heat of combustion of alcohol's

Extracts from this document...

Introduction

Wednesday 19th June 2002 / Jonathan Hayes / 10T An investigation into the heat of combustion of alcohol's AN INVESTIGATION INTO THE HEAT OF COMBUSTION OF ALCOHOL'S 1 PLANNING 1 INTRODUCTION 1 APPARATUS 1 METHOD 2 DIAGRAM 2 HOW I WILL MAKE MY EXPERIMENT A FAIR TEST 2 SAFETY 2 PRELIMINARY WORK 2 RESULTS 3 WHAT I HAVE FOUND OUT FROM MY PRELIMINARY WORK 3 MY RESULTS TO MY EXPERIMENT 3 RESULT AVERAGES 4 ANALYSIS OF RESULTS 4 THE ENERGY TRANSFERRED TO THE WATER. 4 ENERGY TRANSFER PER GRAM OF ALCOHOL 5 THE HEAT OF COMBUSTION PER MOLE 5 MY GRAPH 6 CONCLUSION 7 EVALUATION 7 HOW I COULD MAKE MY EXPERIMENT MORE RELIABLE. 7 ARE MY RESULTS ACCURATE? 8 WHAT I WOULD CHANGE IF I REPEATED THIS EXPERIMENT. 8 Planning Introduction I am trying to determine the heat of combustion for the first five alcohols, which are; ethanol, propanol, butanol, pentanol and hexanol. I am trying to determine whether the amount of Carbon atoms on the molecule affects the heat energy given out by the molecule when burned. I believe that as the size of the molecule increases and the chain of carbons grows longer, then the heat energy given out will increase. I think that this is because when the molecule bonds are broken then they take in energy and then when the bonds are being made they give out energy. In a large molecule, more bonds are made so more energy is given out. Apparatus * Clamp stand * Clamp * Copper calorimeter * Spirit burner * Matches * Thermometer * Ruler * Metal safety tray * Top pan balance (digital scales) ...read more.

Middle

I now have my results and I now need to calculate the energy transferred to the water by each alcohol. And also the energy transferred per gram of each alcohol. The energy transferred to the water can be calculated using the equation; Energy transferred = mass of water (g) X Specific Heat Capacity X Rise in Temperature (?C) This means that all of the results will be exactly the same because in each experiment I used the same mass of water (100g), the specific heat capacity of water which is always 4.2J/g and the temperature rise in each experiment which is always 60?C. If I now put these numbers into the formula I get: Energy transferred = 100g x 4.2J/g x 60?C = 25 200J The answer is 25 200 joules but that number is a little big to work with so I can turn it into 25.2KJ instead. Energy Transfer per gram of alcohol I am now ready to work out my energy transfer per gram of alcohol. This is done by dividing the energy transferred to the water (25.2KJ) by the average mass of alcohol used to give the answer of the energy transfer per gram of alcohol in KJ/g. Alcohol: Energy transferred to water (kJ) Energy transfer, Average Mass of alcohol used Energy transfer per gram of alcohol (kJ/g) Ethanol 25.2 7.91 3.19 Propanol 25.2 6.24 4.04 Butanol 25.2 5.285 4.77 Pentanol 25.2 5.425 4.65 Hexanol 25.2 3.555 7.09 The Heat of combustion per mole I now need to calculate the heat of combustion per mole. ...read more.

Conclusion

There is one anomalous result and that is Hexanol. I think that the wick could have been slightly higher on the Hexanol spirit burner, which could have meant that less heat was lost to the surroundings and it was more efficient than the others. As more energy was out into the water in a shorter space of time, it reached the desired temperature rise of 60?C more quickly and used a lower mass to do this. Therefore giving a higher result. I think that Hexanol should have been at around the 500-kJ/mole mark for its heat of combustion. That is only an estimate and further results would have to be taken to support this. I think that the evidence is definitely reliable enough to support the conclusion that, the more Carbon atoms in an alcohol, the higher the heat of combustion. What I would change if I repeated this experiment. This experiment could be improved but it would take better apparatus. I could try to eliminate most of the factors that I described that were disrupting my results. To do this I would need a large bell jar that I could set my experiment up in. The bell jar would stop draughts getting to the flame and prevent energy loss to the surroundings. I could also pump air into the bell jar, which would provide a constant supply of oxygen. This would encourage a more efficient burning process and prevent soot forming on the calorimeter and preventing heat conduction by being an insulator. I could also weigh my water to be more accurate and cut my wicks to the same size. All of this would improve the quality and reliability of my results and my experiment in general. 1 1 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Organic Chemistry section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Organic Chemistry essays

  1. Investigating the Combustion of Alcohols

    I found the experiment straightforward and simple to follow. I had previously read up about calorimeters in other textbooks to inform myself of the procedure and having carried it out in my preliminary, I was confident with the use of the equipment.

  2. Molar Heat of Combustion of Alcohols

    (This is shown in detail a little later. Safety The experiment we are going to carry out is relatively safe but obvious precautions such as not standing whilst doing the experiment will have to be followed. Goggles and gloves will be worn at all times both when conducting and following the test.

  1. Comparing the heat energy produced by combustion of various alcohols

    Any molecule will conduct heat, radiation happens and can be reduced but not completely halts. I feel that the most limiting factor of the experiment is the convection of air and to a lesser extent, of water. Also during the experiment, some of the water will have evaporated, thus the water mass/temp reading will be altered.

  2. An experiment to investigate the factors that determine the amount of energy released when ...

    I will take my temperature measurements by keeping a thermometer in the beaker of water for the duration of the experiment; when the alcohol has stopped burning totally, I will quickly stir the water with the thermometer and take the final temperature before the water begins to cool down.

  1. Combustion of Alcohols Investigation.

    = 16720 2.27 = 7365Jg-1 =7.365kJ-1 Heat output per mole of methanol = 7.365 x 32 kJmol-1 = 236 Enthalpy = -236kJmol-1 ETHANOL: Heat per gram of ethanol = 16720 1.8 =9289Jg-1 =9.289kJg-1 Heat output per mole of ethanol = 9.289 x 46 kJmol-1 = 427 Enthalpy = -427kJmol-1 PROPANOL:

  2. Comparing the enthalpy changes of combustion of different alcohols.

    = (12x1) + (4x1) + (1 x 16) = 32g 3.15g is the first reading for the replicate one of methanol for the change in mass of the fuel. 3.15g 32g = 0.0984375 moles A mole is 6.02 x 1023 atoms of the chemical. It is also known as Avogadro's constant.

  1. Esters. Esters are formed from an alcohol and carboxylic acid; this is an ...

    Method We did two practices in school seeing the reactions of dilute ethanoic acid, we also did another test where we were making an ester and seeing what it smelt like. I also made a questionnaire asking people on their thought of animal testing.

  2. GCSE Chemistry Revision Notes - everything!

    The salts of carbonic acid are carbonates. Carbonic acid decomposes if you warm the solution, and carbon dioxide is released. So the reaction is reversible. If carbon dioxide is bubbled into an alkali, such as sodium hydroxide, it forms the salt sodium carbonate.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work