3. Potassium chlorate, KC103, decomposes when heated to produce potassium
chloride and oxygen gas.
If 6.50 grams of KClO3 were heated in a test tube, how many grams of oxygen
gas should be given off?

oxygen=2.547g

Explanation:

Based on the question,it was observed that the reaction is reversible

2 moles of KClO3 gives 2 moles of KCl and three moles of O2

Molar mass for KClO3 is 245 g/mol

Molar mass for O2 is 96 g/mol

We are to find the mass of O2 and we Are given the mass KCLO3 is 6.50g

245g of KClO3 gives 96g of O2

6.50g of KClO3 gives xg of O2

Cross multiply

245x=624

X=624/245

X=2.547g

Therefore the gram of oxygen is 2.547g