Answer : The mass of chemical species would remain the same. As potassium chloride does not contains oxygen in it.
The reaction that was supposed to be done would have turned to be opposite as reduction would occur instead of oxidation. Since, Potassium Chlorate is an oxidizing agent, and Potassium Chloride is a reducing agent, It is therefore assumed that if the student was trying to oxidize a particular species would undergo reduction instead.
The crucible when heated with potassium chloride in it would result in melting of the species.