A common laboratory preparation of oxygen gas is the thermal decomposition of potassium chlorate (KClO3). Assuming complete decomposition, calculate the number of grams of O2 gas that can be obtained from 24.82 g KClO3. (The products are KCl and O2).

9.72 g of O₂ are obtained in the decomposition

Explanation:

Reaction of decomposition is:

2KClO₃ → 2KCl + 3O₂

Ratio is 2:3. First, we determine the moles of chlorate

24.82 g. 1mol / 122.55g = 0.202 moles

2 moles of chlorate can decompose into 3 moles of oxgen

Therefore, 0.202 moles of chlorate will decompose into (0.202.3) / 2 = 0.303 moles of O₂

We determine the mass of formed oxygen:

0.303 mol. 32g / 1mol = 9.72 g