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

Determination of the enthalpy change of neutralization

Extracts from this document...

Introduction

Chemistry Laboratory Report 4 Date: 27th October, 2008 Topic: Determination of the enthalpy change of neutralization Objective: To determine the enthalpy change of neutralization between different pairs of acid-base used (thermometric titration) Introduction Two methods are used to determine the concentration of sodium hydroxide solution and the enthalpy change of neutralization. First method: Measure the temperature change of the solution when different volume ratios of acid and base are mixed and reacted. Second method: Measure the temperature change of the solution upon each addition of a specified volume of acid to the base. Results > Method 1: Initial temperature of the solutions = 27.1 oC Volume of NaOH (cm3) 5.0 10.0 15.0 20.0 25.0 30.0 35.0 Volume of acid (cm3) 35.0 30.0 25.0 20.0 15.0 10.0 5.0 1.00M Hydrochloric acid: Final Temperature (oC) 29.3 31.5 33.4 33.8 31.9 30.3 28.6 Temperature change (oC) 2.2 4.4 6.3 6.7 4.8 3.2 1.5 1.00M Ethanoic acid: Final Temperature (oC) 29.2 30.7 32.5 33.5 31.8 29.9 28.6 Temperature change (oC) 2.1 3.6 5.4 6.4 4.7 1.8 1.5 > Method 2: Initial temperature of the solutions = 27.0 oC 1.00M HCl Volume (cm3) ...read more.

Middle

The enthalpy change of neutralization of hydrochloric acid is greater than that of ethanoic acid. As ethanoic acid is a weak acid which partially ionizes in water, some energy given out by neutralization is absorbed to dissociate the unionized acid molecules. Therefore the enthalpy change is smaller than that of hydrochloric acid. > Method 2: a) b) The maximum temperature change is produced when 24cm3 of acid is mixed with 25cm3 of sodium hydroxide solution. no. of moles of acid reacted = 1 x 24/1000 = 0.024 mol concentration of sodium hydroxide solution = 0.02425/1000 = 0.96 M c) Energy change of hydrochloric acid = mc?T = (24+25) x 4.18 x (27.0 - 34.4) = -1.5157 kJ Enthalpy change of neutralization of hydrochloric acid = -1.12024(0.96 x 25/1000) = -63.15 kJmol-1 Energy change of ethanoic acid = mc?T = (24+25) x 4.18 x (27.0 - 34.3) = -1.4952 kJ Enthalpy change of neutralization of hydrochloric acid = -1.12024(0.96 x 25/1000) = -62.299 kJmol-1 d) Also, The heat given out by hydrochloric acid is higher than that of ethanoic acid because some energy is absorbed by the acid during the neutralization to ionize weak ethanoic acid molecule. ...read more.

Conclusion

The heat loss will be very significant as the ratio of acid added to the reaction mixture is small. In order to reduce the heat loss and the percentage error in calculations, the titration must be carried out quickly to obtain more accurate results. -Sources of error > Heat loss to surroundings Heat is lost due to evaporation, convection and conduction. The value of enthalpy change of neutralization calculated will be smaller than the actual value. Better insulation, such as wrapping the polystyrene cup with cotton wool, can be taken to reduce the error. > Some heat may be absorbed by thermometer, stirrer and the polystyrene cup In order to reduce the error, the heat capacities of apparatus should be taken into account in calculations. > The specific heat capacity of solutions is not equal to that of water > Density of the solutions is not equal to that of water Conclusion The enthalpy change of neutralization of HCl is -56.012 kJmol-1 whereas the enthalpy change of neutralization of CH3COOH is -53.504 kJmol-1. The objective of the experiment has been fulfilled as the enthalpy changes of neutralization between different pairs of acid-base were found. ?? ?? ?? ?? P. 1/5 ...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 Physical 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 Physical Chemistry essays

  1. Marked by a teacher

    Heat of Neutralization. Objective: To investigate the ...

    5 star(s)

    Polystyrene foam is a good insulator, even though some heat would be absorbed by the cups and some would be released to the surroundings, it is small enough as compared to the heat absorbed by the solution in the calorimeter.

  2. Marked by a teacher

    Finding out how much acid there is in a solution

    Between these points is orange. We shall use 2/3 droplets of methyl orange in the experiment. This is because, methyl orange is a weak acid. Therefore it will vary the pH of the solution if the indicator was added into the solution. If a large volume of indicator was added, it will affect the acidity

  1. Heat of Neutralization

    When an acid and a base react, the net result is the production of a salt and water. If the salt is water soluble, the net ionic equation for the reaction is Experimentally, a simple solution calorimeter constructed of polystyrene foam cup, a lid and a thermometer would be used.

  2. Lab Report. Objective: To determine the concentration of unknown standard sodium hydroxide solution ...

    Results: Method 1 Using nitric acid: (A graph is attached at page 6) Volume of HNO3(aq) (cm3) 35 30 25 20 15 10 5 Volume of NaOH(aq) (cm3) 5 10 15 20 25 30 35 Initial temp. of HNO3(aq) (?)

  1. The Determination of rate equation

    molarity of only one chemical at a time and keeping the other constant will allow us to determine the rate of reaction. To work out the molarity of different concentration used in the experiment I will be using the dilution equation.

  2. Aim: To determine the conecentrations of hychloric acid and ethanoic acis by thermometric ...

    - 25] E = 2926 J dm-1 K-1 ? Heat energy released = 2926 J dm-1 K-1 For CH3COOH: E = [(100)/1000](4180)[(24.5) - 23] E = 627 J dm-1 K-1 ? Heat energy released = 627 J dm-1 K-1 5. Standard enthaply change of neutralization: ?Hf o = ??E?no.of moles of water formed By the equation: 2NaOH + 2HCl ?

  1. Investigating the Rate of the Reaction between Bromide and Bromate Ions in Acid Solution

    Repeat steps 1-8 with each set of volumes of solutions as shown in the table below. Volumes of solutions required when varying the concentration of bromide solution: Beaker X Beaker Y Volume of 0.01M KBr /cm3 Volume of deionised water /cm3 Volume of 0.005M KBrO3 /cm3 Volume of solution C

  2. Investigating how concentration affects rate of reaction

    Breathing protection. Fresh air, rest. Refer for medical attention. Contact with skin Redness. Protective gloves. First rinse with plenty of water, then remove contaminated clothes and rinse again. Refer for medical attention. Contact with eyes Redness. Pain. Safety goggles, or eye protection in combination with breathing protection if powder.

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