Reaction Conditions and Rate

synopsis

You will examine these factors in detail in subsequent sections. Concentration of reactants, temperature, and the presence of a catalyst will all affect reaction rates. We can also affect the rate of a reaction by increasing the surface area of the reactants.

Review Questions

Go to the grocery store and buy some hydrogen peroxide, a potato, red cabbage, vinegar, and baking soda. Chop up the red cabbage and add an equal amount of water. Simmer the water cabbage mixture for a few minutes and then pour off the liquid into a suitable container. The cabbage juice makes an acceptable acid/base indicator that will be red for acid, blue/green for a base, and purple for a neutral solution. [Go to this site to learn more about using such indicators.] Now put a half-cup of vinegar in each of three containers and add some of the cabbage juice to each. Now add one tablespoon of baking soda to one of the containers and time the change of color of the solution until the color stabilizes. Also note the rate of production of carbon dioxide. Now add two tablespoons of baking soda to another of the containers and make the same measurements. Finally add three tablespoons of baking soda to the last container and repeat the measurements. What is the effect of increasing the concentration of one of the reactants? Post your observations on the bulletin board of WebCT.
Pour about 50 ml of your hydrogen peroxide into each of three containers. In one of them add a piece of potato. In the second container add the same amount of potato but cut it up into small pieces. In the third container put in a penny. Compare the rate of production of oxygen in each of them and post your observations on the bulletin board of WebCT.
Repeat the hydrogen peroxide experiment except now put the hydrogen peroxide in the freezer for 30 minutes before doing the experiment and set up six containers so that you can repeat the above experiment with each container at room temperature and at whatever temperature the hydrogen peroxide is when it comes out of the freezer (measure the temperature). Post any conclusions on the bulletin board of WebCT.