Question

A crucible containing potassium chlorate has a mass is 24.426 g. The crucible is heated according to the lab procedure for this week's experiment and is found to weigh 23.642 g. Write an equation for the reaction and, assuming that all the chlorate decomposed, calculate the mass of the potassium chlorate originally present in the crucible?

Answer 1

Here is a worked example of the exact problem you have (although the numbers are not the same). Just follow the steps.
http://www.jiskha.com/science/chemistry/stoichiometry.html

Answer 2

2.000 g