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

lab report

Extracts from this document...

Introduction

Experiment 9 Aim A. To investigate the existence of hydrogen bonds between ethanol molecules. B. To measure the strength of hydrogen bond formed between ethanol molecules C. To investigate the formation of hydrogen bonds between molecules of ethyl ethanoate and trichloromethane. D. To measure the strength of hydrogen bond formed between molecules of ethyl ethanoate and trichloromethane. Procedure A. 1. 10 cm3 of ethanol was added into an insulated 50 cm3 beaker by using a measuring cylinder. The temperature of the liquid was measured. 2. 10 cm3 of cyclohexane was added to the ethanol in the beaker. It was then mixed well and the lowest temperature attained was recorded. ...read more.

Middle

The highest temperature attained was recorded. Result Temperature change of solution A B C D Initial(oC) 19.5 20.5 20 18 Final(oC) 16 16.5 27 26 Net(oC) -3.5 -4 7 8 Calculation Liquid Formula Relative Molecular mass Density /kg dm3 Specific heat capacity /kJ kg-1 K-1 Ethanol CH3CH2OH 46 0.81 2.44 Cyclohexane C6H12 84 0.78 1.83 Trichloromethane CHCl3 119.5 1.48 0.98 Ethyl ethanoate CH3CO2CH2CH3 88 0.9 1.92 B. Mass of Ethanol: 0.81?(10?10-6)=0.0000081kg Mass of Cyclohexane: 0.78?(20?10-6)=0.0000156kg Total heat absorbed: 4?(0.0000081?2.44+0.0000156?1.83) =0.000193248 kJ mole of limiting reactant (i.e. ethanol): 0.0000081?1000/46=0.000176086 mole The enthalpy change for one mole of ethanol that the hydrogen bond was broken is: 0.000193248/0.000176086 =1.09746 kJ/mole D. ...read more.

Conclusion

The mixing of the two liquid break the hydrogen bonds. As bonds are broken, energy is needed. Therefore, heat is absorbed and temperature drops. B. * Cyclohexane has to be used in excess in order to ensure that no hydrogen bond is presented. * The hydrogen bond strength obtained was not accurate because there is heat lost to surroundings and to the beaker, which was not considered in calculation. C. * The temperature rises. During mixing, the electropositive hydrogen atom in trichloromethane formed hydrogen bonds with the electronegative oxygen atom in ethyl ethanoate. As bonds are formed, energy is given out. Therefore the temperature rises. D. * It does not matter whether using trichloromethane or ethyl ethanoate in excess because using trichloromethane or ethyl ethanoate in excess does not affect the no. of hydrogen bonds per molecule. ...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 ...

    Electronic Balance 0.01g � 0.005g 0.20 = Average (%) error Thermometer 10C � 0.50C 2.5 Measuring cylinder 250 cm3 � 0.5 cm3 0.25 This table shows that the percentage errors for the instruments are very small. This means that my results were fairly accurate and reliable because the percentage errors have a low impact on my results.

  2. Enzyme catalysed decomposition of hydrogen peroxide

    to find out the effect of temperature on the rate of reaction. Plan: Temperatures used ranged from 20-60 degrees celsius in increments of 10 Variables: I will; Keep the volume and concentration of catalase (yeast) constant Keep the pH constant at pH 7 using a buffer Keep the volume and concentration of Hydrogen peroxide constant and the time.

  1. Comprehensive and Detailed Chemistry notes

    Longer chain alkanols produce soot and carbon dioxide upon combustion. C2H5OH(l) + 3O2(g)� 2CO2(g)+ 3H2O(l) -- The main sorces of ethanol are starch and sugar. C6H12O6 � 2C2H5OH + 2CO2 -- Ethanol is a renewable fuel, unlike fossil fuels which are non renewable -- Large area of arable land are

  2. Comparing the enthalpy changes of combustion of different alcohols

    In other words, the enthalpy change of combustion of an alcohol increases as the length of the carbon chain is increased, due to an addition of a CH2 group. Risk Assessment As during this experiment I will be handling potentially harmful chemicals, several safety precautions must be made to ensure the safety of myself and others around me.

  1. Compare the enthalpy changes of combustion of different alcohols

    This also makes the total enthalpy change higher as the number bonds that need to be broken and formed increases. I predict that as the carbon chain increases then the enthalpy change of combustion will also increase. I can use the enthalpy change of alkanes to find a relationship with the enthalpy change of alcohols.

  2. Investigating the Enthalpy Changes of Combustion of Alcohols.

    If we know which bonds are broken and which bonds are made while combusting an alcohol, we can calculate the energy needed to break the bonds and the energy released when bonds are made. Then we can calculate the overall energy difference (enthalpy) and therefore calculate the enthalpy of combustion.

  1. Chemistry Investigation - How does chain length affect: ∆Hcè for alcohols?

    will use draught proofing to see if my attempts to improve heat transfer efficiency are productive and also whether or not I should further my efforts to solve other problems. PRELIMINARY RESULTS: Controlled Substance Start mass (g) End mass (g)

  2. I am going to investigate the difference in enthalpy of combustion for a number ...

    The calorimeter has a mercury thermometer in it, which are very accurate, this will be used to measure the water temperature. I have decided that the calorimeter should be held 1cm above the top of the flame produced by the burning alcohols as so to keep the experiment fair, this being as apposed to having it at a random height.

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