• 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 = (0.5/Change in temperature) x 100 E.g. Temperature change of H2O is 20oC calculated as (0.5/20) x 100 = 2.5% Measuring Cylinder Measures up to 250cm3 and is accurate to � 0.5cm3 % Error = (0.5/Volume) x 100 E.g.

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

    it was not always the size it should have been and did not always point in the correct direction. I also noticed that a black substance was building up on the under side of the calorimeter. This substance was soot this meant that the carbon was not fully combusting to

  1. Comparing The Enthalpy Change OfCombustion Of Different Alcohols

    Evaluation The greatest error in the experiments was heat loss (energy transferred to the atmosphere and equipment). Improvements I could make to my experiment to make it more accurate would be to use a draft excluder as well as insulation using glass wool.

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

    The solution in the volumetric flask was then made up to 250 cm3 using distilled water. * 25cm3 of the hydrolyzed solution was then pipetted into a conical flask. * 4 drops of methyl red indicator was added to the 25cm3 hydrolyzed solution.

  1. Comprehensive and Detailed Chemistry notes

    explain galvanic cells in terms of oxidation/reduction reactions -- A galvanic cell is a device which makes a chemical reaction occur in such a way that it produces electricity. -- The reductant and oxidant are physically separated -- The reductant and oxidant are connected by external circuit made of a conductor to carry electrons.

  2. Salters AS Chemistry Assessed Practical - Enthalpy of Combustion

    Alcohols are a series of organic compounds. They all contain a -OH group. They are different from each other as the length and structure of the carbon chain varies as does the position of the -OH group. All of the alcohols that I am going to be testing are in a liquid state.

  1. producing electricity through wind power.

    Fig 1; illustrates a comparison between renewable and non-renewable energy sources. It is complicated to compare the cost of generating electricity from different energy sources because many of the benefits of renewable energy are for example no pollution and never-ending supply. These benefits do not have a generally acknowledged price.

  2. Comparing the enthalpy change of combustion

    Prediction In a larger molecule, there are more bonds to be broken and made, so the enthalpy change of combustion will increase in comparison with a shorter molecule. Each extra carbon in the molecule introduces one more C-C bond, 2 more C-H bonds, and 2 more O=O bonds to be

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