Iodine Clock Reaction
An investigation on the activation energy for the iodine clock reaction
Introduction:
The iodine clock reaction is a presentation of chemical kinetics, which are the elements that affect the rate of chemical reactions. When the two colorless solutions are incorporated together, no reaction can be spotted. But after a short period of time, the solution turns into a dark blue solution. The term rate of reaction is stated as the decrease in the concentration of one of the reactions or the increase in the concentration of one of the products per unit time, measured by the mol dm-3s-1 . The iodine clock reaction shows that not all reactions are quick and unidirectional proceeds to completion.
Iodine Clock Reaction:
This reaction has many alterations, the alteration used in this investigation is hydrogen peroxide and includes the use of, sodium thiosulfate, potassium iodide, and hydrogen peroxide. The use of starch solution is essential in this experiment as it acts as an indicator for the experiment turning the color of the solution dark blue in the appearance of iodine ions. This allows the end of the reaction to be determined. The clock reaction is shaped by two different reactions. The first reaction is the slow reaction which is: …show more content…
H2O2(aq)+ 2H+(aq)+ 2I-(aq)2H2O(l)+ I2(aq)
This slow reaction is the rate determining step of the reaction and therefore determined as first order.
This is used as a delay mechanism in the reaction, without this, the solution will immediately turn blue/black. When the iodine is formed, it reacts with the sodium thiosulfate, where it gets reduced and forms tetrathionate ions and iodide
ions.
The second reaction which is the fast reaction is presented as:
2S2O32-(aq)+ I2(aq) S4O62-(aq)+ 2I-(aq)
When all the thiosulfate has been used up, the remaining free iodine ion in the solution reacts with the starch to form a complex, which creates a blue/black color. The rate determining step of reactions, suggests that the activation energy for the step will be the greatest between the two steps. The rate determining step will be used to calculate the activation energy.
Collision Theory: There are a few requirements the particles must fulfil for the reaction to occur. Firstly, the particles must collide with adequate energy for this reaction to happen. The energy is referred to as kinetic energy. Secondly, the particles are required to collide with each other at the applicable orientation. By them being in the correct geometry this will allow the reactive parts of particles to have contact with one another.
Activation energy is defined as the minimum amount of energy required to start the reaction. Factors that increases either the frequency of the collisions between the reactants or increases the energy at which the reactants collide will cause the reaction to happen faster. This can help construct the prediction for this experiment as increasing the temperature of the iodine clock reaction means more energy, thus there will be more collisions of particles. Hence, the reaction will occur at an accelerated rate at a higher temperature.
Maxwell-Boltzmann Distribution:
The particles in a liquid are constantly moving. The particles do not travel at the same velocity. They all move at a different speed, the faster the particles are moving the more kinetic energy they contain. The Maxwell-Boltzmann curve show the distribution of kinetic energies in a solution. (Brown &Ford, 280)
Introduction:
The iodine clock reaction is a presentation of chemical kinetics, which are the elements that affect the rate of chemical reactions. When the two colorless solutions are incorporated together, no reaction can be spotted. But after a short period of time, the solution turns into a dark blue solution. The term rate of reaction is stated as the decrease in the concentration of one of the reactions or the increase in the concentration of one of the products per unit time, measured by the mol dm-3s-1 . The iodine clock reaction shows that not all reactions are quick and unidirectional proceeds to completion.
Iodine Clock Reaction:
This reaction has many alterations, the alteration used in this investigation is hydrogen peroxide and includes the use of, sodium thiosulfate, potassium iodide, and hydrogen peroxide. The use of starch solution is essential in this experiment as it acts as an indicator for the experiment turning the color of the solution dark blue in the appearance of iodine ions. This allows the end of the reaction to be determined. The clock reaction is shaped by two different reactions. The first reaction is the slow reaction which is: …show more content…
H2O2(aq)+ 2H+(aq)+ 2I-(aq)2H2O(l)+ I2(aq)
This slow reaction is the rate determining step of the reaction and therefore determined as first order.
This is used as a delay mechanism in the reaction, without this, the solution will immediately turn blue/black. When the iodine is formed, it reacts with the sodium thiosulfate, where it gets reduced and forms tetrathionate ions and iodide
ions.
The second reaction which is the fast reaction is presented as:
2S2O32-(aq)+ I2(aq) S4O62-(aq)+ 2I-(aq)
When all the thiosulfate has been used up, the remaining free iodine ion in the solution reacts with the starch to form a complex, which creates a blue/black color. The rate determining step of reactions, suggests that the activation energy for the step will be the greatest between the two steps. The rate determining step will be used to calculate the activation energy.
Collision Theory: There are a few requirements the particles must fulfil for the reaction to occur. Firstly, the particles must collide with adequate energy for this reaction to happen. The energy is referred to as kinetic energy. Secondly, the particles are required to collide with each other at the applicable orientation. By them being in the correct geometry this will allow the reactive parts of particles to have contact with one another.
Activation energy is defined as the minimum amount of energy required to start the reaction. Factors that increases either the frequency of the collisions between the reactants or increases the energy at which the reactants collide will cause the reaction to happen faster. This can help construct the prediction for this experiment as increasing the temperature of the iodine clock reaction means more energy, thus there will be more collisions of particles. Hence, the reaction will occur at an accelerated rate at a higher temperature.
Maxwell-Boltzmann Distribution:
The particles in a liquid are constantly moving. The particles do not travel at the same velocity. They all move at a different speed, the faster the particles are moving the more kinetic energy they contain. The Maxwell-Boltzmann curve show the distribution of kinetic energies in a solution. (Brown &Ford, 280)