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Determine the Enthalpy of Neutralisation for the following there Acids, H2SO4, HNO3 and H2SO4

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Introduction

A level coursework Determine the Enthalpy of Neutralisation for the following there Acids, H2SO4, HNO3 andH2SO4 Introduction Acid and bases have a very important property that is that they are able to cancel each other out when mixed together in the right proportions, this reaction is called a neutralisation reaction, which can be an exothermic reaction . The standard enthalpy of neutralisation is the heat absorbed per mole when an acid and a base react to form water under standard conditions. In this experiment I will be investigating the values for enthalpy of neutralisation of the three strong acids (HCl, HNO3 andH2SO4) Scientific Background information As explained before, neutralisation happens between an acid and a base. Neutralisation is the formation of water from hydrogen and hydroxide ions H30+(aq) + OH-(aq) --> 2H20(aq) According to Arrhenius' theory 'neutralisation occurs because equal mols of hydrogen ions in the acid are equal to the mols of hydroxide ions in the base so the two react completely to form water'*1. Neutralisation of HCl and NaOH: NaOH(aq) + HCl(aq) --> NaCl(aq) + H2O(l). Neutralisation of HNO3 and NaOH NaOH(aq) + HNO3(aq) --> NaNO3(aq) + H20(l). Neutralization of H2SO4 NaOH(aq) + H2SO4 --> Na2SO4(aq) + H20(l) The enthalpy of neutralisation for strong acids are similar, because 'strong acids fully disassociate in water therefore all hydrogen ions and all hydroxide ions react to from water ...read more.

Middle

First of all I will be careful in pouring the acid so that It does not go onto my skin when in contact with acids the skin will irritate * If the acid gets into contact with the eyes it will be difficult to remove the acid, which would then cause serious damage to the eyes. So for this reason I will wear safety goggles at all times during the experiment, or if any explosions occur I will not damage my eyes. Using the results * Plot the temperature(�C) -vs- time(min) graph. * Use the diagram to draw a line of best fit for the temperature of the solution before addition of alkali and draw the line of Best Fit after addition of alkali as shown in the diagram below * Use this to find the initial temperature and the maxixmum temperature, hence the temperature achange Obtaining Results: Results Tables HCl Conc: 1 moldm-3 Amount of acid added: 25cm3 Final temperature: 27.4�C ?T : 5.9�C Time (min) Temperature of Solution / �C 0 21.0 1 21.5 2 21.5 3 21.5 4 22.0 5 24 6 25.0 7 26.5 8 27.0 9 26.5 10 25.5 11 24.5 12 24 13 23 HNO3 Conc: 1 moldm-3 Amount of acid added: 25.5 Final temperature:25.9�C ?T : 5.9�C Time (min) ...read more.

Conclusion

Firstly the low values of Enthalpy of neutralisation which are result of heat being lost the surroundings before the temperature rise has been recorded. This is probably due to the fact that I didn't use a lid on the polystyrene cup. If I was to repeat the experiment I will make sure I do this to keep in as much heat energy in the cup. 2) Secondly my stirring for the diff acid experiment was not consistence. I may of stirred it differently for all the others, this would mean that more or less heat would of escaped, then required, which affect my thermometer readings. There are 3) Thirdly In my attempt to reduce the time needed to complete my experiment I didn't rinse the measuring cylinder which I was using to measure out the volumes of Acid. Of course this must have led to some contamination of different acids with the acid I was measuring. Next time I will ensure that I wash all apparatus and rinse in appropriate solutions each time I repeat the experiment for different acid. Lastly the thermometer I was using was inaccurate by o.5C. The faulty thermometer would have no effect on the calculated enthalpy of neutralization because the thermometer read 0.50 degrees low consistently so it would have had no effect of the ?T, however next time I will make sure I use a thermometer which is correct to avoid any confusion. ...read more.

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