Given the amount of one reactant, students must use stoichiometry to find the ideal amount of the second reagent to use to create purple fireworks. The teacher ignites each groups' fireworks. Ideal mixture create little or no ash. Student assignment sheet with directions (and different initial amounts) plus teacher information and sample answers are included. This is an exciting and engaging activity that can be used as a stoichiometry quiz.
With one balance per table (two groups), the calculations should take about 10 minutes, the measures another 10 minutes. Ideally, students should be prepared to deliver their mixture to the teacher within 20 minutes. In practice, many students will take longer, particularly if the formula for potassium chlorate is not given and students are not familiar enough with ionic nomenclature.
The teacher will need about one minute per group to announce the group's mixture, ignite it, and wait for student responses. So if there are 15 groups, the teacher should allow about 15 minutes to ignite all the mixtures.