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

Investigating the enthalpy of combustion

Extracts from this document...

Introduction

Chemistry Lab report - Enthalpy of combustion Aim: To see the trend in the combustion of the first five alkanols. Introduction: The standard enthalpy of combustion is the enthalpy change when one mole of a substance completely reacts with oxygen under standard thermodynamic conditions (although experimental values are usually obtained under different conditions and subsequently adjusted). E.g. The standard enthalpy of combustion of ethane is the energy released when one mole of ethane is completely burned in excess oxygen under standard conditions. i.e. the energy change for the reaction: C2H6 + 3.5 O2 --> 2CO2 + 3H2O By definition, combustion reactions are generally strongly exothermic and so enthalpies of combustion are generally strongly negative. It is commonly denoted as or Enthalpies of combustion are typically measured using bond calorimetry, and have units of energy (typically kJ); strictly speaking, the enthalpy change per mole of substance combusted is the standard molar enthalpy of combustion (which typically would have units of kJ mol-1). ...read more.

Middle

Dependent variable > The dependant variable is the amount of fuel burnt after the 20oC rise in temperature. This can be measured using the Digital balance. Constant > The constant variables in this experiment are the conditions in which the trials were performed. The equipment used is also constant since a change in instrument could cause a variation in the data being recorded. RESULTS MASS - Trial 1 Name of fuel Weight of fuel (g) [�0.01] START-END= Change of mass (g) START END Methanol 257.85 257.02 0.83 Ethanol 233.76 232.96 0.80 Propanol 252.24 251.70 0.54 Butanol 282.14 281.51 0.63 Pentanol 268.10 267.48 0.62 MASS - Trial 2 Name of fuel Weight of fuel (g) [�0.01] START-END= Change of mass (g) START END Methanol 253.85 253.04 0.81 Ethanol 287.72 287.12 0.60 Propanol 269.36 269.00 0.36 Butanol 272.24 271.80 0.44 Pentanol 265.16 264.71 0.45 Name of fuel Calculation for Average mass (T1 + T2)/2 (g) Average mass of fuel burnt (g) ...read more.

Conclusion

From the graph we can see a positive correlation between the length of the hydrocarbon chain and the Heat evolved per mole. Evaluation The experiment was fair and safe since all the safety measure were taken e.g. wearing goggles, handling fuels with care etc. The results were fairly accurate but showed some difference between the two trials due to the following sources of errors. Sources of Errors 1. There was a lot of heat lost to the surrounding and so we could not account for all of the ?H. 2. While measuring the gas after the experiment was over, the weight kept on decreasing the longer you kept on the weighing scale. This is because of the capillary action of the wick of the alcohol container (spirit lamp). 3. The time was not stopped on an exact rise of 200C because the temperature does not rise exactly 200C. 4. There was a slight time lapse between the time of setting up the trial, lighting the spirit lamp, and starting the stop watch ?? ?? ?? ?? Prashant Pradhan YR 11 Chemistry HL - Enthalpy 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 International Baccalaureate 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 International Baccalaureate Chemistry essays

  1. Enthalpy of Combustion Lab Report

    Some black soot was formed on the bottom of the calorimeter after the spirit lamp was placed underneath it in the experimental procedure. 3. It was noted that when the mass of the spirit lamp was noted in the beginning of the experiment, the lamp was not warm.

  2. Enthalpy of Combustion of Alcohols Lab

    This was due to the huge uncertainties and errors in the experiment. First and foremost, the biggest problem in the lab which was the largest uncertainty was the wastage of heat to the air. We heated the water in the beaker using the spirit lamps; however, the issue with this

  1. IB chemistry revision notes

    o If the reactant isn't in the r.d.s then you get a linear relation between conc. and rate of rxn. o Reaction order: the order of reaction with respect to a particular reagent. * Temperature o As T increases the particles will move faster to give more collisions per second.

  2. Determining the effect of carbon chain length of an alcohol on its fuel efficiency

    * Record all results on a suitable table and repeat this procedure for the other alcohols. * Controlling Variable: * Mass of the calorimeter: This variable shall be controlled by using the same calorimeter for all experiments. * Mass of water and Mass of the Spirit Burner: These shall be

  1. Hesss Law Lab, use Hesss law to find the enthalpy change of combustion of ...

    Temp.0C (�0.50C ) HCl 0 21 30 21 60 21 90 21 120 21 150 21 180 21 HCl+MgO 190 21 200 21 210 22 220 22 230 23 240 23 250 24 260 24 270 24 280 25 290 25 300 26 330 26 360 25 390 25 420 24 450 24 480 24 EXPERIMENT 2 C time/s(�1sec)

  2. The aim of this experiment is to examine the enthalpy of combustion of the ...

    At the end of the combustion process, weigh out the mass of the alcohol burner and the remaining methanol. 6. Repeat the process using other alcohols (ethanol, propan-1-ol, butan-1-ol and pentan-1-ol). To collect and present the data do the following : 1.

  1. To determine the standard enthalpy of formation of Magnesium Oxide using Hess Law.

    = 15 × 4.2 × 1.95 = 122.85J Number of moles of MgCl2 produced = 0.0012moles Std. Enthalpy of reaction for this trial = ΔHY (Trial 2) = 102375J = 102.38kJ.mol-1. To find the average value for ΔHY, the average of ΔHY (Trial 1) and ΔHY (Trial 2) was taken.

  2. Bomb calorimetry. The goal of this experiment was to use temperature data over ...

    no inflow or outflow of heat and its insulated jacket serves as an ideal environment for the bomb. All the conditions surrounding the bomb and its calorimeter, allow for an adiabatic reaction to take place. Hence, the ΔU is equal to the work (w = -pâV)

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