How Temperature Affects the Reaction between Sodium Thiosulphate and Hydrochloric Acid

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How Temperature Affects the Reaction between Sodium Thiosulphate and Hydrochloric Acid Aim I am going to investigate the reaction between sodium thiosulphate and hydrochloric acid. The main aim is to find out how temperature affects the reaction; if it speeds it up, slows it down or changes it in any way. I will test the effects of temperature by timing how long it takes for a black cross to become non-visible underneath a beaker containing the reactants. I will consider what effect the temperature has on the number of collisions and explain my findings. Background Science The reaction between thiosulphate and hydrochloric acid produces a yellow precipitate of solid sulphur. This makes the solution cloudy and prevents us from seeing clearly through it. The cross below the flask will slowly disappear as the sulphur is produced. When substances react it is due to their particles colliding. Reacting particles must collide with enough energy in order to react. Collisions are needed for any substances to chemically react. There are four main factors that increase the number of successful collisions and therefore speed up a reaction. These are… concentration, catalysts, surface area and temperature. Temperature is important when considering rates of reactions. At low temperatures, particles of the reactants do not have much energy, but when the reactants are heated the particles are given energy which causes them to move faster and collide more often. Not only will more collisions happen, but the collisions will also have more energy and so more of them are successful. This links back to the theory that the more successful collisions there are, the faster the reaction. Preliminary Work I did not do a preliminary experiment for this investigation, but I used my knowledge from investigating a thermos flask to help me plan my work. From the thermos flask investigation I knew that it would take about 30 minutes for the water to cool down 20ºC, which is why I am going to do the first part of this experiment at a high temperature

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