How Does Temperature Affect The Rate Of A Landolt Iodine Clock Reaction

Changes in the rate of reaction can be described in terms of chemical equilibrium. “Chemical equilibrium is a state in which the forward and reverse reactions take place at the same rate” (Wilbraham et al, 2002). The

“The iodine clock reaction was discovered by the Swiss chemist Hans Heinrich Landolt in 1886.” (Scilearn, 2017). There are many variations of the iodine clock reaction but they all involve two colourless solutions being mixed and after a specific period of time, the mixed solutions turn dark blue. The iodate variation of the clock reaction involves the reaction between iodate ions. These being, IO3-, hydrogen sulfite ions, HSO3-, and hydronium ions, H+. To ensure the blue colour change, starch is needed to be added to the solution, reacting with I2. The delay in colour change occurs because as soon as I2 is formed, it immediately reacts with any HSO3- still present and is converted into colourless I-. After all the HSO3- has been consumed, the concentration of the I2 increases and begins reacting with the starch. This is why the dark blue colour is suddenly present. The reaction of the starch reacting to turn the solution a deep blue colour. The reaction occurs in two steps. The first step generates iodide ion (I in Equation 2, which occurs slowly and is the rate determining step. “A rate determining reaction is the slowest step in a reaction mechanism and is assumed to be equal to the overall reaction rate because the reaction cannot go faster than the slowest step.”(Webcache.googleusercontent.com, 2017 ).

If the concentration of the solution is increased the particles have less room to move around which creates a greater chance of collisions. The surface area of the reactant greatly affects the speed of which it reacts because if the reactant is grinded up or cut up the solution has more room to get to it. The reaction rate can be calculated by the formulae; rate of reaction = total amount of reactant used or product made ÷ time taken. (Collision theory and rates of reaction, 2013)

From the results that were collect throughout the experimental investigation has proved the hypothesis to only be partially right. Multiple tests were made when conducting the experiment, two clear solutions were combined at various temperatures and concentrations. The hypothesis states that by adjusting the concentration of the reactants will cause the reaction to either speed up at a higher concentration or slow down at a lower concentration. In the reaction temperature should have a similar effect on the experiment, in that increasing the temperature will cause an increase of particle movement and cause more collision, thus increasing the reaction rate. Therefore decreasing the temperature will decrease the rate of the reaction. From the results given in Tables 2 and 3 it shown that every time the concentration is halved the time is increased. When the concentrations of both KIO3 and NaHSO3 are decreased the time has increased, some concentrations having a higher increase than others. In each concentration decrease the time is at least doubled from the previous concentration time, which is therefore increasing the rate of the reaction.

Clock reactions are among the most visually entertaining demonstrations of chemistry. Simply put, a clock reaction is one where two substances are mixed and there is a time delay where there is no visually discernable change in the system. During this delay, one of the chemical species, the clock chemical, has a very low concentration. The end of this induction period is marked by a rapid increase in concentration of the clock chemical (S.J. Preece et al., 1999). This rapid increase in concentration is what triggers effects such as a sudden colour change.

Three factors that can affect the rate of reaction are temperature, pH and the salinity.

Many factors effect reaction rates, two shown above include temperature and concentration. Concentration affects the rate of reactions because the more concentrated a solution the more likely collisions between particles will be. This is simply because there are more particles present to collide with each other. When the temperature is higher, particles will

The rate of a chemical reaction often depends on reactant concentrations, temperature, and if there’s presence of a catalyst. The rate of reaction for this experiment can be determined by analyzing the amount of iodine (I2) formed. Two chemical reactions are useful to determining

In this experiment it was observed that not all chemical reactions occur at the same rate. Chemical reactions occur when one or more substances are changed into other substances. The properties of a chemical reaction require three things. First, they need a source of energy for molecules to encounter each other. Second, they require to proceed at a steady rate. Third, they must proceed in a particular direction until they reach equilibrium. There are two types of chemical reactions that can occur: endergonic and exergonic reactions. In these reactions there are both reactants and products. In exergonic reactions the reactants (starting materials of a reaction) are higher than the products (results of a reaction). This is opposite for endergonic

To determine what factors influence the rate of a chemical reaction and to make predictions based on these

9. Does temperature have any effect on reaction rate? If so, why does it occur?

The reaction rate for this is slow at room temperature. The definition of reaction rate is the rate of change in concentration of either reactants or products. It is dependent on the concentration of the reactants and on the temperature. In a rate law, a mathematical expression, the relationship between the reaction rate and the concentrations of reactants can be demonstrated. For example, the rate law for the rate of decrease in concentration of bromate ion would be:

Many things can affect the rate of reaction. One being the natural reactivity of the reactants themselves given their bonds and ionization energies. Also, the concentration

Objective: This lab was performed to help students understand what enzymes do, what they are, and how they are effected by temperature, pH, and concentration. This lab write up only contains information based on the temperature portion of the lab. Introduction: In lab 5; enzyme activity, yeast solution was used as an enzyme to test the rate that oxygen was produced.

Chemical kinetics involving reaction rates and mechanisms is an essential part of our daily life in the modern world. It helps us understand whether particular reactions are favorable and how to save time or prolong time during each reaction. Experiment demonstrated the how concentration, temperature and presence of a catalyst can change the rate of a reaction. 5 runs of dilution and reaction were made to show the effect of concentration on chemical reactions. A certain run from the previous task was twice duplicated to for a “hot and cold” test for reaction rate. The prior run was again duplicated for a test with