Formal Report- Kinetics of Reaction: the Iodine Clock Reaction

In reference to the collision theory, molecules act as small spheres that collide and bounce off each other, transferring energy among themselves when the collide. In order for a reaction to occur, there must be collisions between molecules. Through experimentation, factors are discovered that influence the reaction rates of chemical reactions include the concentration of reactants, temperature, surface area, the physical state of reactants, and a catalyst. This experiment regarding the factors that affect reaction rate tests the effects of increased concentration and

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

Then the disk should be placed into the hydrogen peroxide solution and times for a reaction. Then another disk is placed into a beaker labeled potato extract for 5 seconds, then placed into the hydrogen peroxide solution and timed for a reaction. The hypothesis for the pH test were correct because the reactions did slow down as the pH got higher. In the data, the average rate of reaction for the highest pH level was 180 seconds or higher. The lowest pH level had the fastest reaction of them all at about 61 seconds.

“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 ).

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.

A chemical reaction is when substances (reactants) change into other substances (products). The five general types of chemical reactions are synthesis (also known as direct combination), decomposition, single replacement (also known as single displacement), double replacement (also known as double displacement), and combustion. In this lab, the five general types of chemical reactions were conducted and observations were taken before, during, and after the reaction. Then the reactants and observations were used to determine the products to form a balanced chemical equation. The purpose of this lab was to learn and answer the question: How can observations be used to determine the identity of substances produced in a chemical reaction?

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

This experiment will measure the rate of oxidation of iodide ions by persulphate ions to derive the rate law for the reaction. Starch will be added to the reaction to facilitate the measure of time during the reaction. The reactant solutions will contain (NH4)2SO4 and KI, represented as:

This paper is about chemical reactions and chemical reaction types. All the data gathered was from conducting multiple experiments. Each experiment was performed carefully and analyzed to obtain the necessary information for the paper. That information included the four signs of a chemical change, the rnx type, and more.

The purpose of this experimentation is to find the differences of the concentration of the enzyme amylase to determine what outcome of the changes will have on the rate of the reaction between starch and amylase. We hypothesizes that as the reaction temperature of amylase solution and starch solution rises the pH reaction rate of both solutions will rise. Materials: 6 test tubes Marker

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

4) Try and propose a mechanism for the reaction using the orders of reaction taking into account the iodine, propanone and sulphuric acid.

Two catalyst reactants are used in the experiment, thiosulfate and starch, to dictate the time of reactions.

The equation of the line in run 1 between the two points is y – y1 = m(x – x1)