Investigation into temperature change Essay

Introduction. The following is an experiment into temperature change in an exothermic reaction taking place between Sodium hydroxide (NaOH) and Hydrochloric acid (HCl) and also how the concentration of the acid will vary these results. The characteristics of the reaction feature a neutralisation, an energy change (shown as a temperature change) that is usually exothermic (gives out heat). The reaction of neutralisation is exothermic because of the bonds being broken and made in the reaction. When bonds are broken, energy in those bonds are taken in, and in this case, are noted as a temperature change, the temperature increasing. If it were an endothermic reaction, the temperature would lower, because the reaction is using up more energy breaking the bonds, this is noted and a temperature change, this time, showing how temperature decreases. The acid and alkali compounds dissolve into water, acid into hydrogen ions, and alkali in hydroxide ions. Neutralisation with hydrogen and a hydroxide, at the end, the product is water (also with left over sodium chloride). There is energy released in kilojoules when a reaction takes place. The main aim is testing the effect of different concentrations and the effect it has on temperature. Variables. To make this test fair, we must only change one variable, that being the concentration of the hydrochloric acid, but we must also make sure, that the alkali concentration is constant. Also, for the sake of fair testing, the room temperature must stay the same, as is will vary results greatly on day to the next. Trial run. The trail run was to determine a number of details; The first, being the correct ratio of concentration, what I mean to say is, how many cubic centimetres the solution of acid and water will vary each time we do the experiment. We have decided to each time, keep the volume constant at 25cm cubed, but diluting the acid by 5cm cubed each time. Also, we decided that the use of polystyrene insulation was not needed as in the trail run; it had no real effect on the end temperature. Apparatus. The following is a list of apparatus we used with the experiment: 1) Burette 2) Measuring cylinder X 2 (0-50cm3) 3) Digital thermometer (with a temp range of -50 degrees Celsius to 150 degrees Celsius.) 4) Beaker Safety. Within safety, basic labs rules apply, these include, clear workstations and no loose clothing, but special safety rules must be out in place for this, as the use of acids and alkalis, safety goggles need to be worn. Step by step plan. First, gather up all equipment needed in experiment, then, measure volumes and concentrations that are needed in the experiment. Then, record the start temperature, after that, mix together the acid and alkali in the beaker, and wait until its peak temperature, then record it. Repeat this three times in order to check for reliability. Use exact guidelines on this to repeat experiment for different concentrations. Accuracy. In accuracy, we use the preset variables we also make sure that volumes and concentration are constant and accurate. Prediction. My prediction of what will happen is that when the acid is added to the alkali, the reaction will cause the temperature to go up, but with each concentration the temperature rise will go up, but not to the same extent of what is was beforehand. This prediction was come to with collision theory in mind; the double the temperature the double the amount of successful collisions, meaning double amount of heat being given off. Once the acid is in excess there will be no further temperature rise. Results Table Conclusion In conclusion, I conclude that my graph follows the directly proportional trend because the science in my prediction was correct (higher temperature, more collisions, more heat given off). This shows my prediction was correct, and that all the science within this experiment in. Evaluation My repeats in the experiment were close, and that would mean that they were, and still are reliable. Also, within these repeats there were no anomalous  results, this again showing a well carried out experiment. My method worked extremely well, and I feel it is the best possible method to use in further experiments. But if needs be to change the experiment in some way, perhaps difference in the concentration of the alkali instead of the acid, may alter the results in someway. Even the use of either more controlled conditions or different insulation is something to look into. Choosing another variable to control is also a feasible option.