A number laboratory experiments exist using chemical reactions that allow students to measure the reaction rate. These experiments use both traditional equipment and the new generation of interfaced probeware.

• Determination of a Rate Law
• Bromphenol Blue

Doing Chemistry Experiments

048, Combustible Powders
A combustible powder is injected into a closed vessel that contains a burning candle. An explosion ensues.

051, Hot Penny Catalysis
A piece of copper metal heated to red heat, when placed in the vapor of an oxidizable alcohol, continues to glow red as the result of continuing oxidation and the attendant release of heat.

052, Catalyzed Burning of Sucrose
A cube of ordinary table sugar (sucrose) does not burn readily. When ashes (a source of alkali) are rubbed on the surface of the cube, however, it burns easily.

112, First Order Reaction Analogy
A known number of pennies is placed in a box. The box is covered and shaken. All of the pennies with tails up are removed and the number counted. The box is reclosed, reshaken, and all of the tails-up pennies removed and counted. This process is repeated until very few pennies remain in the box. The data is used to illustrate a first order reaction.

113, Temperature and Reaction Rate
Light sticks that use chemiluminescent reactions to glow in the dark are placed in reaction baths at different temperatures. Sticks in the hot bath give off much more light than those in room temperature baths. Sticks in cold baths give off the least light.

114, MicroScale Iodine Clock Reaction
A kinetics experiment is performed in such a way that a fixed amount of a reagent is consumed by a product of a slow chemical reaction. The time required for a fixed amount of thiosulfate to be used up is measured and related to the concentration of one of the reactants, hydrogen peroxide. From this information, the order of hydrogen peroxide in the reaction is determined.

130, Kinetic Study of Thiosulfate in Acid
The acidification of thiosulfate solutions leads to the formation of colloidal sulfur. This sulfur scatters light in the Blocktronic colorimeter, and permits a quantitative study of the reaction. A hands-on "microscale" chemical version of this experiment is included.

132, Kinetics of Crystal Violet/Hydroxide Ion Reaction
Crystal violet undergoes a reaction in which the dye molecules are converted into a colorless substance. This reaction is first order in dye and in hydroxide ion. Crystal violet is a cation and the resulting product is neutral. As a result, the reaction rate is very sensitive to changes in ionic strength.

LABS Experiments

Kinetics: A Study of Reaction Rates
Have you ever wondered how chemists slow down reactions that are potentially explosive or speed up reactions to synthesize a product in a shorter period of time? In this laboratory activity, we will use a familiar reaction:

Mg(s) + 2 HCl(aq) --> MgCl₂(aq) + H₂(g)

to investigate this problem. The rate may be measured in several different ways. For example, it may be expressed as the volume of H₂ gas produced per second or as the mass of magnesium metal used per second.

To design a procedure to measure the rate or speed of the Mg/HCl reaction. You will then identify two factors other than catalysis to alter the speed of this reaction and examine each factor quantitatively.