To study the effect of changes in concentration on the rate of a chemical
Chemistry can be defined as the science of matter, and its interaction with other
matter. In this experiment, the effect on concentration on the rate of a chemical reaction
is observed. A chemical reaction is defined as a change in the arrangement of atoms or
molecules to yield substances of different composition and properties. In this particular
case, different concentrations of potassium iodate solution are reacted with starch-sulfite
solution to observe the effect of changes in concentration on the chemical reaction rate. A
chemical reaction can be described using a chemical equation. A chemical equation is a
symbolic representation of the relationship between the reactants and products of a
chemical reaction. A net ionic equation, an equation that shows only ions that undergo
change during a chemical reaction, simplifies a chemical equation to simply what is
reacting, by providing a net reaction. In this particular lab, the net equation is represented
by the following:
In some reactions, when a reaction takes place, usually there is a physical change,
or something able to be observed. In this reaction, however, the change is not as evident.
Therefore, an indicator of starch must be used. The starch will react with I
formed, indicating the end of the chemical reaction. When I
and starch react, they form a
blue complex, physically indicating that the reaction is completed.
The rates of reaction are dependent upon several factors, such as concentration of
reactants, temperature, surface area, action of catalysts, and the nature of the reactants.
This lab primarily focuses on the effect of the concentration of the reactants on the rate of
the reaction. Concentration is a term used by scientists to designate the amount of solute
dissolved in a given quantity of solvent or solution. The greater the amount of solute
dissolved in a certain amount of solvent, the more concentrated the resulting solution.
The concentration of solutions can be expressed quantitatively through several ways, with
the two primary ways being molarity and molality.
, expresses the concentration of a solution as the number of
moles of solute in a liter of solution. Molality, symbol
, expresses the concentration of a
solution as the number of moles of solute in a kilogram of solvent. When an ionic
compound dissolves, it dissociates into its component parts, or its individual ion. Each
individual ion retains the concentration of the original compound, but once dissolved in a
liquid, changes the overall concentration. For example, a 1.0
solution of NaCl is 1.0
ions. In solution, it would be 2.0
Similarly, a 1.0
solution of Na