Rate of Reaction Experiment - Sodium Thiosulphate and Hydrochloric Acid :: GCSE Chemistry Coursework Investigation

Rate of Reaction Experiment - Sodium Thiosulphate and Hydrochloric Acid To investigate the effect, of changing the concentration of a reactant, in a chemical reaction on it rate. The equation used for the experiment was: Sodium + Hydrochloric Sulphur + Sulphur + Sodium + water Thiosulphate acid dioxide chloride Na2S2O3 + 2HCl(aq) S(s) + SO(g) + NaCL(aq) + H2O The Collision Theory can explain reaction rates perfectly. A chemical reaction can only occur between particle when they hit or collide at a minimal amount of energy need for them to react this is called the activation energy. The rates of a reaction depends on how hard and often the reacting particles collide. Basically, particles have to collide in order to react 1) They must also collide hard enough to give a reaction. 2) Pressure can also affect reaction rates between gases, an increase in pressure pushes the molecules closer together making them collide more often, which in turn increases the reaction rate. 3) A presence of a Catalyst could affect the result, as it is a substance that alters the rate of the reaction. without itself appearing in the final result. When a solution becomes more concentrated it means there are more particles of reactant knocking between the water molecules, this means collisions between important particles more likely. In a gas, increasing the pressure means the molecules are more squashed together, there will then be lots more collisions. Higher temperature also increases the energy of the collisions, it makes particles move faster. Faster collisions can only b caused by increasing the temperature. enzymeThis is shown in the diagram opposite. The Maxwell-Boltzmann Distribution and activation energy For a reaction to take place particles have got to collide with energies greater than or equal to the activation energy for the reaction, this can be marked on Maxwell-Boltzmann Distribution. I have chosen to investigate the effect concentration has on a reaction. I chose this because it is the easier to prepare and will provide the most accurate set of results. Equipment --------- Hydrochloric acid (5cm3) Sodium thiosulphate Paper with black cross on Conical flasks Goggles Water Pipette Measuring cylinder Method To provide fair accurate results it is important to ensure that the same printed cross is used for each experiment. In this the experiment the amount of Sodium Thiosulphate is varied each time in comparison to the amount of water used, the solution will always add up to 45cm3. There will always be 5cm3 of hydrochloric acid used. The experiment was performed at room temperature as this made the experiment easy to perform, as no heating or cooling devises were necessary.