Factors affecting the rate of a chemical reaction The kinetics of a Thiosulfate Solution - Lab Report Example

The first protonation occurs at the sulfur atom. (Holleman & Wiberg, 2001) Various approaches are used to study the kinetics of reactions. A usual procedure is to monitor some property, such as intensity of color due to a reactant or product, which changes during the course of a reaction. In the present experiment, the priority studied is the precipitation of a product, sulfur, which forms when solution of hydrochloric acid and Thiosulfate are mixed. On mixing a solution of acid, such as HCI, and a thiosulfate solution, there is an initial time-delay, then a precipitate of sulfur appears fairly sharply.

The time interval between initial mixing and sulfur precipitation is a measure of the initial rate of reaction (i.e. the amount of time for a given amount of product, sulfur, to form). Recall that a rate for a chemical reaction is expressed as an amount of product formed (or reactant used up) divided by the time interval of the change: The aim of my experiment is to determine the dependence of the initial rate of reaction on the initial concentration of thiosulfate ion. The concentration of the other reactant, H+, will be kept constant.

A higher initial concentration of thiosulfate will lead to faster rate of reaction, since an increase in the number of thiosulfate ions per unit volume will lead to higher probability for successful collision. (2) A solution of 1 M sodium thiosulfate, is available (center bench or hood). Add 70 mL of this solution to 210 mL of water to make a solution approximately 0.25 M in thiosulfate. We will refer to this as your "stock thiosulfate solution". (7) The experiment is now repeated four more times, using progressively more dilute thiosulfate solutions.

Note, however, that for each experiment, the disappearance of the "X" corresponds to formation of the same amount of precipitated sulfur in the reaction mixture. The diluted solutions are prepared as follows: Both