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

Enthalpy. This experiment's aim is to find out, enthalpy change of a reaction, and to determine whether it is exothermic or endothermic.

Free essay example:

Lab report on Emthapy

Aim :

This experiment's aim is to find out, enthalpy change of a reaction, and to determine whether it is exothermic or endothermic.

Apparatus :

Measuring Trays                        

Weighing Scale

Citric acid

Sodium Carbonate

Polystyrene cup


Reaction beaker + lid

Copper Sulphate

Zinc (powdered)



  1. Pour 25 ml of Copper Sulphate into the reaction beaker.
  2. Place the reaction beaker in the polystyrene cup and put the thermometer in the cap.
  3. Record the temperature of the solution.
  4. Add the 0.5 grams of Zinc powder and close the lid immediately.
  5. Record Maximum change of temperature.
  6. Repeat steps 1 – 5 but this time use citric acid in place of Copper Sulphate and 3 grams of Sodium Carbonate instead of zinc.
  7. Calculate energy change for the amounts of substance used.
  8. Calculate the amount of the reactant in solution in the cup.
  9. For each reaction calculate energy change per mole of the reactant which was in solution at the start.
  10. Write a symbol equation for the first reaction and a word equation for the second one.
  11. Write the energy change per mole of citric acid.
  12.  Draw an energy level diagram for the enthalpy change of both reactions.

Diagram of Apparatus:


Starting temperature:



Trial 1

 Trial 2

Trial 3

Average temperature


Zinc Sulphate






Sodium Citrate




Final temperature:



Trial 1

Trial 2

Trial 3

Average temperature


Zinc Sulphate






Sodium Citrate





There were two different levels of reactions, The 1st reaction did not fizz to much, the 2nd  had a rather vigorous reaction, as soon as the reactants were mixed.


The results show that the first reaction, which gave out heat to its surroundings, was exothermic, and the second reaction, which took heat from its surroundings, was endothermic. After this has been established, a few more things may be noted.

Firstly, we know that the formula for energy evolved to be E = mc∆T, where m is mass of reactant, c is its specific heat capacity and T the temperature in Kelvin.

We disregard the use of Kelvin here as it does not change the result in any way. We also assume that the specific heat capacity of the reactant is 4.2 Joules/g cm, and the mass to be 25 grams.

Using the equation, the energy evolved from the first reaction is equal to 25 x 4.2 x 5, or 525 Joules. In the second reaction, we find the energy evolved to be 25 x 4.2 x 6, or 630 Joules. The copper sulphate was in a 1 mole/dm3 amount, and so 0.025 moles of it were used. Since the citric acid was in the same ratio, 0.025 moles of that was used as well.

525 Joules of energy was evolved from 0.025 moles of copper sulphate. Therefore from 1 mole, 525 x 1/0.025, or 21 Kilojoules would be its energy change per mole.

630 Joules of energy was evolved from 0.025 moles of citric acid. Therefore from 1 mole 630 x 1/0.025, or 25.2 Kilojoules would be its energy change per mole.

The equation for the reaction 1 is the following:

CuSO4(aq) + Zn(s) ZnSO4(aq) + Cu(s)

The equation for the second reaction is the following:

Sodium Carbonate(s) + Citric acid(aq) Sodium Citrate(aq) + Carbon Dioxide(g) + Water(l)

The enthalpy change for the first reaction is – 525 Joules, due to the reaction being exothermic, and the enthalpy change of the second reaction is 630 Joules, due to the reaction being endothermic.

This student written piece of work is one of many that can be found in our International Baccalaureate Chemistry section.

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

Related International Baccalaureate Chemistry Skills and Knowledge Essays

See our best essays

Related International Baccalaureate Chemistry essays

  1. Chemistry lab report, Exothermic and Endothermic Reactions

    Initial temp: 19 oC Final Temp: 36 oC Calculation: 36 oC - 19 oC = 17 oC * Zinc + Hydrochloric Acid (Zn + HCL) Initial temp: 18 oC Final Temp: 26 oC Calculation: 26oC - 18oC = 8 oC Formulas: Magnesium + Hydrochloric Acid --> Magnesium Chloride + Hydrogen

  2. The Enthalpy of Neutralization

    Calculating Percentage Error of Observed Enthalpy Value [(Observed Value - Expected Value) � Expected Value] x 100 = Percentage error [(-50.2 kJ�mol-1 H2O (� 5.17 kJ�mol-1 H2O) - -57.3 kJ�mol-1) � -57.3 kJ�mol-1] x 100 = 12.4% Experiment 3 - Enthalpy of neutralization for nitric acid and sodium hydroxide NaOH(aq)

  1. Determining an enthalpy change of reaction

    Temperature/?C Results Table 2.1 6. Perform 2 more trials, repeating steps 1-5 two more times. Data collection and processing Raw Data Table: Time/s 0 30 60 90 120 150 180* 210 240 Temperature/?C 22.5 22.5 22.5 22.5 22.5 22.5 26 31 32 Time/s 270 300 330 360 390 420 450 480 ?

  2. IA-Enthalpy Change of Reaction - Zinc and Copper Sulphate.

    This is a source of uncertainty because the temperature probe had to be isolated from the solution when the lid was opened, causing a sharp plummet in the temperature graph. * Some of the materials used, such as the temperature probe and the Styrofoam cup, had to be shared with many other students and were not always cleaned well.

  1. Chemistry Lab Report- Determining the Enthalpy of Enthalpy Change, H, for a Redox Reaction ...

    Also, as the temperature of the surroundings increased there was some lost in the energy from the system. We know that there was an excess in zinc, because there was some left overs with black powdery substance from the reaction.

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

    For 120 seconds, 24 readings were taken and noted in a pre-made data collection table. 9. Once 120 seconds were up, the calorimeter was emptied and cleaned so that another trial of the same experiment could be performed. Safety Precautions: 1.

  1. Electrolysis of copper sulphate

    The circuit should now look something like the schematic to the right (figure 1), check this, and continue if correctly assembled. Five electrolytic cells have now been connected in parallel and ready for electrolysis. Figure 1. 1. The Electrolysis 1.

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

    Calculate the average temperatures for every alcohol that has been used in the previous experimental process. 2. Use graphing techniques to represent your results. 3. Calculate the heat given out to the known sample of water in the boiling tube.

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