How Concentration affects the rate of reaction :: GCSE Chemistry Coursework Investigation

How Concentration affects the rate of reaction I am investigating the rates of reaction and how the different variables can affect it. I know that the temperature, a catalyst, concentration, the surface area, light and pressure of a gas can affect the rate of reaction. In this particular experiment I am going to investigate on how the concentration of one of the reactants affects the rate of reaction. To show that the concentration does affect the rate of reaction I am going to carry out the reaction of sodium thiosulphate and hydrochloric acid. The reactant I am going to change in concentration for each experiment/reading is sodium thiosulphate. Word Equation Sodium + Hydrochloric Sodium + Sulphur + water + Sulphur Thiosulphate acid Chloride dioxide Chemical Equation ================= Na2S2O3(aq) + 2HCl(aq) -> 2NaCl(aq) + S(s) + H2O(l) + SO2(g) Equipment ========= Sodium Thiosulphate (NaSO) of different concentrations and volumes 5cm Hydrochloric acid (HCl) Water of different volumes Paper marked with a cross 2 Measuring cylinders Conical Flask Stopclock I will set the equipment up as shown in the diagram below Method I am going to measure out the right amount (50cmÂÂ ³) and concentrations of the sodium thiosulphate and hydrochloric acid. I will vary the concentration of the sodium thiosulphate but will still keep the volume of the acid the same. I will keep the volume (5cmÂÂ ³) and concentration (2.0 moi/dmÂÂ ³) of the hydrochloric acid the same. The table below shows the amount of water I will add to the sodium thiosulphate to vary the concentration in each experiment. --------------------------------------------------------------------------------- Experiment Volume of 0.15 mol/dm (cm) Volume of water Concentration sodium Number sodium thiosulphate (cm (Cm) thiosulphate solution (mol/dm) 1 50 0 0.15 2 40 10 0.