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

Enthalpy Change - Alcohols

Extracts from this document...

Introduction

In this experiment, I will be investigating the levels of energy found in alcohols. Fuels like petrol and diesel come from non-renewable fossil fuels, that power machines like cars. However, these are running out fast, and an alternative fuel must be found as soon as possible. Alcohols could be used as fuels and also it's from a renewable source, as they can be grown and fermented. For this experiment I will need to calculate Enthalpy change (?H). Change Enthalpy Mass of Water Change Temperature Specific heat Capacity (4.2 j/g) Firstly, I will need a calorimeter - A calorimeter is a device used for measuring the heat of chemical reactions or physical changes as well as heat capacity. To find the enthalpy change per mole of a substance I will need to burn the alcohol underneath the calorimeter and during this process temperatures are noted. To hold the burner closer to the calorimeter I will use wooden blocks to support it. Attached to the top of this calorimeter will be a water pump, to suck up as much as possible of the hot air. The alcohol burners I will use will be 3x Ethanol, 3x Methanol, 3x Propanol & 3x Butanol, I will do the experiment three times for each to get a 'fair' result. ...read more.

Middle

22.55�c. After my preliminary testing, I found that the burner could easily be affected by heat loss via the calorimeter; if the gap between the burner and the calorimeter is too much then too much heat will be lost. If it's too close, the burner will not produce the full potential of heat. This is why I am using wooden blocks to firmly hold it in the correct place. Another way of preventing heat loss is a simple water pump, this quite simply attaches to the top if the calorimeter and sucks up the hot air through the calorimeter. Finally, the calorimeter could produce hotspots in the water, so a stirrer will be necessary. I am not expecting perfect results every time, but if an anomalous result occurs I will still include it but show the anomaly either in my results tables or on my graph. Time (seconds) Temp (�c) Alcohol 0 30 60 90 120 150 180 Weight Before (g) Weight after (g) Ethanol 22.5 25.6 25.8 26.3 27.4 28.5 29.5 31.49 30.94 Methanol 21.4 21.5 21.9 22.4 23 23.7 24.6 29.37 28.80 Propanol 21.2 21.5 21.9 22.3 22.8 23.4 23.9 32.62 32.34 Butanol 20.5 22 21.1 21.5 21.8 22.2 22.5 30.41 30.13 Time (seconds) ...read more.

Conclusion

The relative mass: Methanol is 32 Ethanol is 46 Butanol is 60 Propanol is 74 Following this, I need to divide the energy by mol; this will give me my result in J mol-1, the final stage will be to divide this number by 1,000 to get my final result in KJ mol-1. The correlation between the Mr and energy of combustion is as one gets higher, so does the other. Although you need more energy per Mr to break the bonds, the higher the Mr the higher the energy you get back out of it. I believe that my evidence is fairly reliable, but obviously not perfect. My results to follow a trend but enthalpies of combustion are not even half way close. Techniques should be improved to receive better results, for example; the way we equilibrate the calorimeter and check the temperature. The calorimeter should be properly equilibrated before we even touch it, but also every time we touch the calorimeter the temperature of the water could be affected, it may only be 1� or so but the results will be effected. Also the temperature needs to be checked throughout the calorimeter as hotspots are produced. The results - energy of combustion - we received compared to the actual results are quite different, e.g. Methanol; my result is 221.21 KJ mol-1 whereas the actual results are 726 KJ mol-1. ?? ?? ?? ?? Chemistry Coursework Page ...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. Comparing the enthalpy changes of combustion of different alcohols.

    * Stirring the water using a stirring rod and NOT a thermometer. Some different aspects of fair testing cannot be done. One such example is measuring the amount of water to fill the copper can with. If you use a measuring cylinder there will always be some water droplets left

  2. Investigate the enthalpy change of different alcohol

    (correct to 2 d.p.) Original 1st trial Original 2nd trial Original 3rd trial I have decided to repeat my experiment three times on each of the alcoholic fuel so as to increase the reliability the results. I would then use the average on the increase of water temperature to calculate the energy transferred using the equation mentioned earlier on.

  1. "Could Sainsbury's add value to their business by using an alternative fuel for their ...

    When there are such negative externalities, marginal social cost is higher than marginal private cost; and social optimum occurs at a lower level of output. If a firm will continue to produce at the level of its private optimum, this will ultimately result in the welfare loss to the society (shaded area on the diagram).

  2. Molar Heat of Combustion of Alcohols

    I have constructed the following graphs to help me with the formulae: This is to show me the energy absorbed by each container for 1g of alcohol each. Test 1 Test 2 Test 3 Average Propanol 10080 9240 17017 12112 Butanol 24500 21375 18000 21292 Ethanol 13233 13919 10613 12588

  1. This is a mini-project on fuel - topics include petrol and fossil fuels.

    Factories use these chemicals to make plastics, textiles and other products. Polythene, for example, is made from a gas that comes from oil. Chemicals from oil are also used to make drugs, fertilisers, detergents and dyes and paints in all colours.

  2. Comparing the Enthalpy Changes of Combustion of Different Alcohols

    The alcohols that I am using in my experiment are: -Methanol CH3 -OH -Ethanol CH3 -CH2 -OH -Propan-1-ol CH3 -CH2 -CH2 -OH -Propan-2-ol CH3 -CH2 (-OH)-CH2 -Butan-1-ol CH3 -CH2 -CH2 -CH2 -OH When an alcohol contains more than two carbon atoms, as is often the case, isomeric alcohols are possible (same number of molecules but different structure).

  1. Comparing the enthalpy changes of different alcohols

    * Draft shielding (heat proof mats) Method 1) Put 200cm3 of cold water into a copper calorimeter (or equivalent) and measure and record its temperature. 2) Support the calorimeter over the spirit burner (10cm above the top of the spirit burner), containing either methanol or hexane, using a clamp and stand.

  2. GCSE Chemistry Revision Notes - everything!

    Sodium carbonate is sold as washing soda and is effective as a degreasing agent. Metal Hydroxide Chloride Sulphate Nitrate Carbonate Lithium LiOH LiCl Li2SO4 LiNO3 Li2CO3 Sodium NaOH NaCl Na2SO4 NaNO3 Na2CO3 Potassium KOH KCl K2SO4 KNO3 K2CO3 Group 2 Group 2 are all metals with low melting points and densities.

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