Answer:
The correct answer is 45.9 g O₂
Explanation:
The descomposition reaction is the following:
2 KClO₃ → 2 KCl + 3 O₂
From this,, we know that 2 mol KClO₃ produce 2 mol of KCl and 3 mol of O₂. Now, we can use the molar mass of the compounds and rewrite the equation with the mass of each compound:
MM KClO₃= 39 g/mol + 35.4 g/mol + (3 x 16 g/mol)= 122.4 g/mol
2 KClO₃ = 2 mol x 122.4 g/mol= 244.8 g
MM KCl= 39 g/mol + 35.4 g/mol= 74.4 g/mol
2 KCl= 2 mol x 74.4 g/mol= 148.8 g
MM O₂= 2 x 16 g/mol= 32 g/mol
3 O₂= 3 mol x 32 g/mol= 96 g
With this, we can write a recipe in mass:
2 KClO₃ → 2 KCl + 3 O₂
244.8 g → 148.8 g + 96 g
244.8 g of KClO₃ produce 148.8 g. If we have 71.1 g KCl, the mass of KClO₃ from which this mass of KCl is produced is:
244.8 g KClO₃ ---------------------- 148.8 g KCl
x ------------------------ 71.1 g KCl
x= 71.1 g KCl x 244.8 g KClO₃/148.8 g KCl= 116.97 g KClO₃
Finally, we calculate the mass of O₂ produced by 116.97 g of KClO₃ taking into account that the recipe says that 244.8 g of KClO₃ produce 96 g of O₂.
244.8 g KClO₃ ---------------------- 96 g O₂
116.97 g KClO₃----------------------- x= 116.97 g KClO₃ x 96 g O₂/244.8 g KClO₃
x= 45.87 g O₂= 45.9 g O₂
