Molar mass KClO₃ = 122.5 g/mol and O₂ = 32.0 g/mol
2 KClO₃ ----------------> 2 KCl + 3 O₂
2 122.5 g KClO₃ ---------> 3 32 g O₂
250.0 g KClO₃ ------------> ?
mass of O₂ = 250.0 3 32 / 2 122.5
mass of O₂ = 24000 / 245
mass of O₂ = 97.959 g
number of moles O₂ :
1 mole --------- 32.0 g
? mole -------- 97.959 g
moles = 97.959 1 / 32.0
= 97.959 / 32.0
= 3.061 moles of O₂
hope this helps!
