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

Enthalpies of combustion.

Extracts from this document...


Enthalpies of combustion In this experiment we are trying to see how the enthalpies of combustion change with 4 different alcohols. The alcohols we will be using are. ?Methanol (CH3OH) ?Ethanol (C2H5OH) ?Propanol (C3H7OH) ?Butanol (C4H9OH) As you can see all of these alcohols are made out of the same compounds. What we want to know is how the number of Carbon atoms (C) affects the enthalpy of combustion. We set up the apparatus as shown above. We put a thermometer in and measured the temperature of the water. The alcohol was weighed and put under the beaker. The wick was set alight and we watched until the temperature had gone up approximately 10oC, extinguished the alcohol with the lid of the spirit lamp, took it to the front and weighed it again. ...read more.


29.09090909 Propanol 20 33 13 191.63 191.42 0.21 61.9047619 Propanol 20 32 12 191.42 191.21 0.21 57.14285714 Butanol 20 34 14 174.98 174.68 0.3 46.66666667 Butanol 20 34 14 174.68 174.52 0.16 87.5 We then did a table which showed the averages of all the alcohols. It looked like this: Alcohol Initial Temp. (oC) Final temp. (oC) Temp. Change (oC) Initial weight (g) Final weight (g) Mass used (g) Temp. rise/gm used Methanol 20 34 14 182.285 181.74 0.545 25.71186441 Ethanol 19.5 34 14.5 193.025 192.635 0.39 42.80632411 Propanol 20 32.5 12.5 191.525 191.315 0.21 59.52380952 Butanol 20 34 14 174.83 174.6 0.23 67.08333333 Next we worked out the heat absorbed by the H2O. To do this we had to calculate it using this method: (Mass of H2O*4.2*temp. ...read more.


This is because it takes more of the heat to break down the carbon atoms. We also found that the butanol left a sooty residue on the beaker. This happens because there is not enough oxygen in the air to react with the carbon and break it down. This could also explain why the graph stops sloping in a straight line after propanol, because there aren't enough oxygen atoms to react with the carbon atoms therefore slowing the reaction down and causing the dip in the graph. If we had done it in a controlled environment the graph might have looked like this: As you can see the graph has a constant slope now. This would be how it would look if the experiment was done in a controlled environment. Philip Pearson 11WG ...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.

    This is because the distance between the bonds increases. So in summary the longer the hydrocarbon the greater the enthalpy change of combustion due to the low volatility. If we compare the average values obtained by my experiment to the average values from a data book and work out the error this pattern can be further proven.

  2. 'Enthalpy of Combustion'.

    The best-fit line is straight with a positive correlation and shows that the results are also proportional and increase by 123 kJ per carbon atom. The graph does not go through 0 and this is because if there were no carbon atoms, the hydrogen and oxygen remaining would still produced

  1. An Investigation into the Enthalpies of the Combustion of Alcohols.

    This is where electrons are transferred from one ion to another, so there is an electrostatic force between the ions. 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.

  2. Molar Heat of Combustion of Alcohols

    Equipment: Burners for all three alcohols A copper calorimeter A test-tube A beaker A clamp stand Heatproof mats (draft excluder) Heatproof gloves Goggles Digital Thermometer A stopwatch Matches/ Lighter Electronic Scales Prediction: I think that the alcohols with the most carbon atoms will have higher amounts of energy released from them.

  1. The Combustion of Alchohols

    2 carbon atoms * Propanol (C3H7OH) 3 carbon atoms * Butanol (C4H9OH) 4 carbon atoms * Pentanol (C5H11OH) 5 carbon atoms most carbon atoms These are the first five basic alcohols that share common properties such as being colourless, non-conductors and have a neutral pH. They are exclusively linked together by the pattern in the number of carbon atoms in each of the alcohols' molecules.

  2. Comparing the Enthalpy Changes of Combustion of Different Alcohols

    The only difference between the alcohols in this series is their length and the structure of their hydrocarbon chains. This causes change in their physical properties for example their boiling point and viscosity. Alcohols are named from the parent alkane, for example: Ethanol is an alcohol derived from Ethane but with an -OH group replacing an -H atom.

  1. Comparing the enthalpy changes of combustion ofdifferent alcohols.

    4C - H | | | | OH H H H Butan-2-ol H H H H | | | | H - 1C - 2C - 3C - 4C - H | | | | H OH H H Pentan-1-ol H H H H H | | | | |

  2. GCSE Chemistry Revision Notes - everything!

    + OH- (aq) ? NH3 (g) + H2O (l) Carbonates Most carbonates split up to give a metal oxide and carbon dioxide when you heat them. You can test the carbon dioxide given off using limewater and there may be some helpful colour changes as well. If you add a dilute acid to a solid carbonate, carbon dioxide is produced in the cold.

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