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

Enthalpy changes

Extracts from this document...

Introduction

Enthalpy Changes Analysis Results Recording Test 1 Test 2 Test 3 Units Mass of CaCO3 + weighing bottle 3.50 3.52 3.50 g Mass of empty weighing bottle 1.04 1.01 1.00 g Mass of CaCO3 used 2.50 2.50 2.50 g Temperature of acid initially 21.50 22.00 21.00 �C Temperature of solution after mixing 24.00 24.00 23.00 �C Temperature change during reaction 2.50 2.00 2.00 �C Mass of CaO + weighing bottle 2.52 2.30 2.40 g Mass of empty weighing bottle 1.12 0.90 1.00 g Mass of CaO used 1.40 1.40 1.40 g Temperature of acid initially 22.00 22.50 21.00 �C Temperature of solution after mixing 32.50 32.50 30.00 �C Temperature change during reaction 10.50 10.00 9.00 �C ?H1 The Reaction between CaCO3 + HCL J = m.c. ?T is used to calculate the energy produced using heat capacity of HCL, and 50ml of HCL with the temperature change in the reaction. J = m.c. ?T 50 x 4.2 x 2.5 = -525 J 50 x 4.2 x 2 = -420 J 50 x 4.2 x 2 ...read more.

Middle

If, say 1�C of heat loss was saved lost on each of the above reactions then the resultant enthalpy change would have been very different as we can see by doing the calculations below ?H1 J = m.c. ?T 50 x 4.2 x 3.5 = -735 J 50 x 4.2 x 3 = -630 J 50 x 4.2 x 3 = -630 J AVG = -665 J 665 = -26.6 kJ/mole 0.025 If we do the same for the ?H2 reaction then we get -91 kJ/mole. If we then use Hess's cycle to find ?H3 then we get 117.6 kJ/mole. This shows just how 1�C of heat loss can affect the results of the reaction. To combat this next time I will conceal the experiment in a polystyrene cup. Polystyrene has excellent heat absorbing qualities, and would ensure that little heat is lost during the reaction. I could also put a lid on the beaker during the reaction. ...read more.

Conclusion

?H1 J = m.c. ?T 53 x 4.2 x 2.5 = -556.5 J 53 x 4.2 x 2 = -445.2 J 53 x 4.2 x 2 = -445.2 J AVG = -482.3 J 482 = -19.28kJ/mole 0.025 If we do the same for the ?H2 reaction then we get -87.5 kJ/mole. If we then use Hess's cycle to find ?H3 then we get 68.22kJ/mole. This shows just how 3ml more of HCL could affect the reaction. It could affect it even more as well. If there was a =3ml error on the first reaction and a -3ml on the second then we get 77.6kJ/mole. To stop this from happening again I could use a 50ml pipette to measure the solution to a much smaller resolution Another error in measurements was that the thermometer's resolution wasn't small enough. We could only detect a 0.5�C change in temperature. As we have seen before a temperature error can drastically change the results. To avert this problem next time, I cold use a loggit temperature probe. This is an electronic device that measure temperature to 2 d.p. This would make my results much more reliable. ...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 ...

    16.8 0.066956521 250.91 Propan-1-ol (1) 16.8 0.034333333 489.32 Propan-1-ol (2) 16.8 0.035 480.00 Propan-1-ol (3) 16.8 0.0405 414.81 Butan-1-ol (1) 16.8 0.020675675 812.55 Butan-1-ol (2) 16.8 0.040405405 415.79 Butan-1-ol (3) 16.8 0.023783783 706.36 The table shows the average enthalpy change of combustion Name of Alcohol Average mass of fuel used (g)

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

    These were just a few of the problems discovered. This method was therefore modified with the use of spirit burners, a lagged copper calorimeter and draught shields to reduce heat loss and also a smaller volume of water was used.

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

    Reliability and precision There is a source of uncertainty in the precision of the apparatus which was used. Each measuring instrument is designed to measure to a certain level of precision. To compare the importance of the precision errors for different measuring instruments, a percentage error calculation was carried out

  2. investigating the amount of ascorbic acid present in fruit

    that is the amount of fruit sample I used in the titration. Orange: 0.64 = 0.064mg of vitamin C in the orange sample 10.00 So here I divided the mg of vitamin C in the orange sample (that was found to be 0.64mg)

  1. Comprehensive and Detailed Chemistry notes

    or compost. A soil sample is saturated in a dish with distilled water. Bariu sulfate powder is added to the surface, and soil water soaks into the barium sulfate. Drops of indicator are added to wet barium sulphate, and the colour change is observed.

  2. Investigating the Enthalpy Changes of Combustion of Alcohols.

    The heat capacity of water actually varies at different temperatures (see table and graph below). See (3) Because of the variations in the heat capacity of water, the actual heat capacity used in my equations will depend on the where the temperature rise occurs.

  1. Compare the enthalpy changes of combustion of different alcohols

    List of Alcohols to choose from: * Methan-1-ol * Ethan-1-ol * Propan-1-ol * Propan-2-ol (I will not use this because it is not a primary alcohol. It has different chemical properties to the other alcohols although it has the same molecular formula as propan-1-ol.

  2. Determination of the Enthalpy Change of a Reaction

    This can described in the form y = mx, m being the gradient of the rate of temperature increase in respect to mass of reagents present. Standard deviation will give us an indication as to the accuracy of the results.

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