The Effect of Concentration on the Rate of Reaction :: GCSE Chemistry Coursework Investigation

The effect of concentration on the gait of reaction amongst sodium thiosulphate and dilute hydrochloric ditThis investigation is about rates of reaction and what affects them.In this case I am going to look at hydrochloric acid and sodiumthiosulphate which is a precipitation reaction causing the solution togo cloudy. They react as in the equations belowsodium thiosulphate + hydrochloric acid - sodium chloride + siemens +sulphur dioxide + waterNa2S2O3(aq) + 2HCl(aq) - 2NaCl(aq) + S(s) + SO2(g) + H2O(l)A reaction leave behind only occur where the particles of the reactants meetand combine. This is called the collision theory. For a reaction tooccur particles have to clash with each(prenominal) other. Only a small percentresult in a reaction. This is due to the energy hindrance to overcome.Only particles with enough energy to overcome the barrier will reactafter colliding. The minimum energy that a particle must have toovercome the barrier is called the activation energy, or Ea . The sizeof this activation energy is different for different reactions. If thefrequency of collisions is increased the rate of reaction willincrease. However the percent of successful collisions remains thesame. An increase in the rate of reaction can be achieved byincreasing the frequency of collisions. Therefore to increase the rateof reaction it is necessary to cause more particles to collide harderand collide more often. There are several ways to do this and thesemake up the factors for this experiment. They are listed below alongwith predictions as to their affect on the reaction. possible FactorsTo make sure I carry out a fair test I will only change theconcentration of sodium thiosulphate. I will keep the followingfactors the same.Increasing the pressure. By reducing the volume in which the sameamount of particles exist the pressure is increased. Once the same get along of particles are in a smaller area there is less space in whichto move and so the particles are more like ly to gibe each other. It istherefore possible to predict that increasing the pressure will resultin an increase in the rate of reaction. I will not test this variablebecause we dont have the facilities to test it. However pressure is acontinuous variable.Catalyst. A catalyst is a separate substance that speeds up areaction. After the reaction has happened it gets left behind. Thismakes this variable unsuitable for the type of experiment I am goingto do.Temperature. By giving the particles extra energy they will movefaster. This means that they cover more ground and are therefore more