Rate of Reaction Coursework :: GCSE Chemistry Coursework Investigation

An experiment to find the rate of reaction between two liquids Introduction This is an experiment to determine the effect of changing the concentration of sodium thiosluphate (Na S O (aq)) on the rate of reaction between sodium thiosulphate and hydrochloric acid (HCL (aq)). HCl+sodium thiosulphatearrowsodium chloride+sulphur dioxide+sulphur+water. HCl(aq) + Na2S2O3(aq) arrow NaCl(aq) + SO2(g) + S(s) + H2O(l) If one were to place hydrochloric acid and sodium thiosulphate into a beaker a white cloudy solution is left in the beaker. The rate of the reaction can be controlled by concentrating one of the liquids, or one could add water to dilute the mixture to slow the reaction. Method Apparatus Two beakers of 50cm3 Sodium Thiosulphate Hydrochloric acid Conical flask Measuring tube-10cm3 Measuring tube-50cm3 The apparatus is set up as shown above. I will place 50cm3 of Sodium Thiosulphate; I will keep Hydrochloric acid at a constant rate of 5cm3. Then I will reduce the sodium thiosulphate and increase the water, for example: 50cm3: 0cm3 40cm3: 10cm3 30cm3: 20cm3 20cm3: 30cm3 10cm3: 40cm3 When the reaction is complete the solution left should be white and cloudy, to test this; I will place a piece of paper with a cross on it. If I cannot see the cross on the paper then the reaction has finished. Constants * Hydrochloric acid * Temperature * Length of X on paper * Room temperature Variables  · Sodium thiosulphate  · Water Hydrochloric acid will be kept at a constant rate because the experiment is about changing the concentration of sodium thiosulphate. The temperature will be kept constant with a precise thermometer in the solution. The paper with the X on it will always be the same piece of paper. The room temperature will be kept constant because I will make sure the windows are closed. Sodium thiosulphate will be varied because that is the point of the experiment. The water will be varied to dilute the reaction. Scientific explanation In order for the sodium thiosulphate and Hydrochloric acid to react their particles must: * Collide with each other * The collision must have enough energy This is shown by the explanation below: The particles in the liquid If the collision has enough If the collision move around continually. energy, a reaction takes place does not have here an acid particle is enough energy about to collide with a no reaction sodium atom occurs. The acid particle bounces away again. If there are a lot of collisions then the rate of the reaction is fast. If there are not many, the rate is low. The rate of a reaction depends on how many successful collisions there are in a given unit of time. There are three main ways of speeding up a reaction: * Changing the concentration