1515L - Percentage of Potassium Chlorate in a Mixture
The third experiment (from page 53 in Catalyst) involves carefully heating a mixture of KClO3 and NaCl in which the amount of each salt in the given mixture is unknown. You will not be doing the initial test of the unknown that is suggested in the text. You will carry out the larger scale version in the large Pyrex test tube from your kit. Be very careful to have the opening of the test tube pointing back towards the bench, not at yourself or your neighbor.
Your Pyrex test tube needs to be as clean as possible and dry in order for this experiment to work well. Wash the tube with soap and water and drain off as much liquid as possible. You then heat tthe test tube over a low flame in order to dry it for use. Be careful here. If you heat it too quickly with too hot of a flame the tube will crack.
Heating the Sample
Weigh your clean, dry test tube then add the unknown sample that is made up of KClO3 and NaCl. Reweigh the tube then clamp it near the top of the tube as shown on the left. Heat the sample from the top down and not from the bottom of the tube to avoid any rapid buildup of gas and a possible explosion.
You may have to use one of the available Meeker burners to ensure that all of your sample melts. These burn hotter than regular Bunsen burners so "waft" the burner past the sample as shown in the video below, i.e. do not simply place the burner under the sample directly as the tube may crack.