1. A thermometric titration was carried out using 1.00moldm3 sodium hydroxide solution and dilute hydrochloric acid of unknown concentration. 50.0cm3 of the sodium hydroxide solution was placed in a suitable apparatus and 5.00cm3 portions of the hydrochloric acid were added. The mixture was stirred after each addition of acid and the temperature of the mixture was measured. Both solutions were initially at 20C. tha rocults obtained were as shown in the tahlo (a) Plot a grap", in moldm3, of the hydrochloric acid. (b) Calculate the enthalpy change of neutralisation, per mole of water formed, of the reaction. [Assume the specific heat capacity of the solution formed is 4.18Jg1K1 and that its density is 1gcm3.] (c) Suggest suitable apparatus for carrying out the above experiment. (d) In further experiments, the following enthalpy changes of neutralisation were determined, again using 1.00moldm3 solutions at 20C. HF(aq)andNaOH(aq)CH3COOH(aq)andNaOH(aq)neutH=68.6kJmol1neutH=55.2kJmol1 Suggest why each of these values is different from the values for HCl(aq) and NaOH(aq). Suggest why these values are different from one another. [Note: Part (d) of this question is beyond what is expected of you at IAS. However, if you do som research into what is meant by a weak acid, and also consider the energy changes involved whe acid molecules ionise in water and also when the ions are subsequently hydrated, you should b able to answer it.] In the experiment described in Question 1, a 50cm3 pipette was used to measure the volume of sodium hydroxide solution, and a 50cm3 burette was used to add the hydrochloric acid. The measurement uncertainty for the pipette is 0.10cm3. The measurement uncertainty for each read of the burette is 0.05cm3 and for the thermometer is 0.05C. (a) Calculate the total percentage measurement uncertainty in the use of: (i) the pipette, (ii) the burette and (iii) the thermometer. (b) Considering the description of how the experiment was carried out, suggest any possible procedural errors. State how you would carry out the experiment in order to minimise the e of these errors