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

Experiment to measure the enthalpy change of combustion for hexane and methanol

Extracts from this document...

Introduction

TASK 1 (a) Carry out the activity on measuring the enthalpy change of combustion for hexane and methanol and calculate your result. In this experiment i will burn the fuel methanol (this is an alcohol which can be used as an alternative fuel) and arrange the apparatus to get most of the energy transferred to the water. Method * Firstly i will pour 200cm3 of cold water in a copper calorimeter then i will use a thermometer to record the temperature of the water. * By using clamp stands and bosses i will support the calorimeter over the spirit burner containing the methanol fuel * I will arrange a suitable system which will stop any heat from escaping to the surrounding by placing heat mats all around the apparatus. * Before starting the experiment i will record the weight of the spirit burner and record my results * Now i will place the burner under the calorimeter and light it, i will be stirring the water using the thermometer as its being heated * I will continue doing this until the temperature has risen about 15-20oC. ...read more.

Middle

= ?H-658 KJ/mol-1 Mass of 1 mole of methanol = 32g (C=12+H=(1x4)+O=16) Mass of fuel burned= Average/Mass --> 0.658 / 32 = 0.0205625 Energy Transferred by 1 Mole of Fuel = Mass of Water (g) x Change in Temperature x 4.18J (this is the energy required to raise the temperature of 1g of water by 1oC) = 50g x 8.32 x 4.18J = 1738.88J Heat given out by 1 mole of methanol = 1738.88 / 0.0205625= -84565.59J --> -84.5656 KJ/mol-1 Describe the terms endothermic and exothermic in terms of bond breaking and bond forming When a chemical reaction takes place bonds are broken in the reactants this is known as endothermic as energy is absorbed from the surroundings to break these bonds you can see this happening in the above ENDOTHERMIC REACTION the reactants are below the products meaning that the reactants need more energy from the surrounding the overcome the activation barrier and less energy is given out. The bonds of the products are weaker than those of the reactants and this is seen as a + (plus) ...read more.

Conclusion

The main error which could have given me invalid results was the calorimeter as when it gets heated it also gets covered in soot & heat loss 4. Also as the spirit burner is covered up there is another factor which could affect the experiment which is the oxygen levels as if they drop incomplete combustion. To improve the practical i could use a different copper calorimeter each time or rinse off the black soot. Procedural Errors: A Weighing balance was used to measure the mass of the spirit burner before and after the experiment the balance was to 2 decimal places Methanol before the experiment Percentage error = 0.005 x 100 = 0.0225% 22.83g Methanol after the experiment Percentage error = 0.005 x 100 = 0.0225% 22.212g I also used a measuring cylinder to measure the amount of water i used 2 x 100cm3 measuring cylinder to get 200cm3 i ensured lots of accuracy by looking at the bottom meniscus while measuring to produce more accurate reading i could have used pipette. ?? ?? ?? ?? ...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. Find the enthalpy change of combustion of a number of alcohol's' so that you ...

    error, which we are going to use later when we collect our results. It will help minimise the amount of error in the experiment. % Error: Electronic Balance It is set to 2 decimal places and therefore reads to the nearest 0.01g.

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

    Also although the calorimeter was lagged and it now had a plastic lid heat was also still being lost through holes in the lid which were made in order to allow for the thermometer and the plastic stirrer. As people walked past draughts were causing the flame to flicker and

  1. The aim of this experiment is to produce Aspirin. This is an estrification in ...

    1.5067g Mass of container = 0.0000g Number of moles present in 0.1 mol dm-3 HCL N = c x v = 0.1 x 8.50 1000 = 0.00085 moles (present in 25cm3 of NaOH) Number of moles present in 1.0 mol dm-3 NaOH N = c x v = 1.0 x

  2. Comprehensive and Detailed Chemistry notes

    same mass as an electron but possess a positive charge 12454Xe + 11p � 12355Cs + 2(10 n ) 12355Cs � 12354Xe + 01e 12354Xe � 12353I + 01e * identify instruments and processes that can be used to detect radiation GEIGER-MULLER PROBE AND COUNTER -- The GM probe and

  1. Investigating the Enthalpy Changes of Combustion of Alcohols.

    We can use the energy released from the reaction to heat up a particular surrounding that has a known specific heat capacity (SHC). The SHC of a substance is the amount of energy needed to raise gram of that substance by one degree Celsius, or by one degree Kelvin (the Kelvin scale is the standard temperature scale).

  2. Compare the enthalpy changes of combustion of different alcohols

    The reason for this is due to the added hydroxyl group (-OH), this means that one of the bonds of oxygen has already been made so there is less energy needed as there are less bonds to be broken. This is the same for both Propane/Propanol and Octane/Octanol.

  1. Determination of the Enthalpy Change of a Reaction

    / 177.8 = 60.4% Considering the scatter diagrams, they show the expected positive correlation. This is, the more reagents added, the more products there are. The amount of products formed is directly proportional to the temperature change since this is the amount of energy transferred as a result of the breaking and forming of intra-molecular bonds.

  2. Enthalpy - investigate the difference in enthalpy of combustion for a number of alcohols

    By looking at the equation for the reaction and more importantly looking at the bonds that are being broken and made, it is possible to work out an estimation for the amount of energy that will be released in the reaction.

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