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

Comparing the enthalpy changes of combustion of different alcohols.

Extracts from this document...

Introduction

COMPARING THE ENTHALPY CHANGES OF COMBUSTION OF DIFFERENT ALCOHOLS Analysis Results Table Alcohol Initial Temperature (c) Final Temperature (c) Initial Mass (g) Final Mass (g) Methanol 20 35 188.36 186.40 Ethanol 20 35 233.92 232.31 Propan-1-ol 20 35 244.67 243.24 Butan-1-ol 20 35 213.54 212.29 Pentan-1-ol 20 35 195.44 194.46 Hexonal 20 35 217.38 216.66 Alcohol Mass Loss (g) Relative Formula Mass Number of Carbon Atoms Methanol 1.96 32 1 Ethanol 1.61 46 2 Propan-1-ol 1.43 60 3 Butan-1-ol 1.25 74 4 Pentan-1-ol 0.98 88 5 Hexonal 0.72 102 6 Calculations The first step I need to take in calculating the amount of heat absorbed by the water in each experiment is to find out how much energy is transferred to the water to raise its temperature. ...read more.

Middle

= / 1000 for kJ = 205.71 kJ mol-1 (2.d.p) Table for all enthalpy changes Alcohol Moles Enthalpy Change (kJ mol-1) Methanol 0.06125 205.71 Ethanol 0.03500 360.00 Propan-1-ol 0.02383 528.75 Butan-1-ol 0.01689 746.00 Pentan-1-ol 0.01113 1132.08 Hexonal 0.00758 1662.27 Conclusion As my graph shows, as the number of carbon atoms in the alcohol molecules increase, so does the enthalpy change of combustion. This is because the more carbon atoms, and therefore hydrogen bonds, that the molecule possesses, the more energy is needed to break the larger amount of bonds. Evalutation I am pleased with my experiment as it returned results to confirm my prediction. I did not observe any anomalies which suggests that the results were accurate in relation to each other (suggesting that there were no human errors) ...read more.

Conclusion

9. The size of the wick. 10. Not all of the water was the same temperature. 11. The flame size changed due to the type of alcohol, hence it was a different distance away from the beaker each time. I could obtain a better picture of how the number of carbon atoms affects the heat of combustion in two ways. 1. I could extend my current experiment by testing other alcohols such as heptanol or octanol as well as by doing more repeats to increase the accuracy of my results. 2. I could conduct a similar experiment with other homologous series of hydrocarbons such as the alkanes or the alkenes. This would allow me to compare the results from each experiment and compare how the number of carbon atoms in the chain affects the heat of combustion. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level 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 AS and A Level Organic Chemistry essays

  1. Marked by a teacher

    Comparing the enthalpy changes of combustion of different alcohols

    3 star(s)

    15884/ 1000 = 15.884 KJ ?H�C = Q / mole = 15.884/0.019 = 836 kJmol-1 Methanol: Q = m x c x ?T = 200 x 4.18 x 16 = 13376J 13376/ 1000 = 13.376 KJ ?H�C = Q / mole = 13.376/0.0484 = 276 kJmol-1 Propan-1-ol: Q = m

  2. Find the enthalpy change of combustion of a number of alcohol's' so that you ...

    I have chosen to use a Aluminium calorimeter because Aluminium has a high thermal conduction value, which means that it is a good conductor of heat so the heat transferred in the reaction will all be transferred to the water and will enable me to measure the amount of energy transferred to the water more accurately.

  1. Investigating the Enthalpy Changes of Combustion of Alcohols.

    (Again think about how can reduce inaccuracies.) PRELIMINARY RESULTS Combustion of Ethanol Mass of Burner Before Exp : 172.25 g Mass of Burner After Exp : 170.30 g Mass of Ethanol Burnt : 001.95 g Mass of Water Used : 200 g (200 cm3)

  2. Comprehensive and Detailed Chemistry notes

    Table and outline the relationship between position of elements in the Periodic Table and acidity/basicity of oxides -- Metals of Groups I and II all form basic oxides. The basicity increases down each group -- Most non-metals form acidic oxides.

  1. The aim of this experiment is to investigate the enthalpy change of combustion for ...

    on the carbon atom this in turn means that the hydrogen atom and carbon atom become partially positively charged. The movement of electrons due to the electronegativity of one or more atoms creates a partial charge or .This is known as a dipole.

  2. Investigating factors affecting the heat of combustion of alcohols.

    Constants Throughout this experiment I am going to keep the following things constant: 1. The time that the alcohols are left to burn for. I have decided to keep this constant, as it means that I will be able to easily compare the heat of combustion having found the rise in temperature and change in mass.

  1. Comparing The Enthalpy Change OfCombustion Of Different Alcohols

    + 5H2O(l) Pentanol C5H11OH(l) + 7.5O2(g) 5CO2(g) + 6H2O(l) Below is a prediction table for the predicted enthalpy of combustion values for the other alcohols worked out in the same way as the one above: Alcohol Enthalpy change when bonds are broken (kJ mol-1)

  2. Comparing the enthalpy change of combustion of alcohols down a homologous series.

    Enthalpy is the total energy content of the reacting materials, in this case the alcohols, it is given the symbol H. Enthalpy itself cannot be measured, but it is possible to measure enthalpy changes, when energy is transferred to or from a reaction system and changes from one enthalpy to another.

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