Research questionHow does altering the concentration of potassium iodide ion affect the time of its rate of reaction with hydrogen peroxide measured in the time taken for the formation of a blue-black solution, using the iodine clock method?IntroductionChemical reaction is a process in which the successful reaction between particles result in changes in one or more molecules into other molecules . We actually encounter chemical reactions in our everyday life, more than we think. Batteries, combustion, and even our digestion require some sort of chemical reaction in order to work. One method that we use in order to get a better understanding of chemical reactions are through experiments using chemical clocks. Chemical clocks are a mixture of reacting chemical compounds that results in periodic changes due to their concentration. They usually serve as an example of non-equilibrium thermodynamics. One of the most famous chemical clock reactions is the iodine clock reaction, which this paper will be investigating. The iodine clock reaction was discovered by Hans Heinrich Landolt in 1886. It serves as a demonstration to display chemical kinetics in action. There are several factors that affect the rate of reaction such as temperature, pressure, presence of catalysts and concentration of the reactant. In this experiment, the concentration will be the independent variable, and it will be manipulated in order to test the effect it has on the rate of reaction in the reaction between potassium iodide (Kl) and hydrogen peroxide (H2O2). In this case, if only the concentration of the reactant (Kl) is changed and the concentration of the hydrogen peroxide is unchanged, the rate of reaction can be found. It can be deduced by measuring the time taken for the formation of a blue-black color starch. This is the result of the two colorless solutions mixing, and it indicates the formation of products. There are two reactions occurring in the solution when potassium iodide and hydrogen peroxide are mixed. First, in a slow reaction, iodine is produced: H2O2 + 2I? + 2H+ ? I2 + 2H2O(where potassium and sodium ions are spectator ions) However, as the formation of the blue-black starch complex is instantaneous, a delaying mechanism is used in order to delay the formation of products. Therefore, in a fast reaction, sodium thiosulphate is added to the potassium iodide and sodium peroxodisulphate, and iodine gets converted to 2 iodide ions: 2S2O32? + I2 ? S4O62? + 2I?Following this reaction, the solution changes color to a blue-black solution. HypothesisBased on the collision theory, for a reaction to happen, the two reacting particles involved must collide with one another, the collision must be energetic enough to overcome the activation energy of the reaction, and the collision must occur with the correct geometrical alignment. The reaction will also be affected by the number of particles, as the more there are, the more frequently will collision occur and the more often will reactions happen in order to form products. Consequently, an increase in the reactant concentration will increase the rate of reaction, which will be reflected by the time it will take for the blue-black solution to occur.