A sample of KClO3 on decomposition yielded 448 mL of oxygen gas at NTP. Calculate (i) Weight of oxygen product (ii) Weight of KClO3 originally taken (iii) Weight of KCl produced.
2KClO3Δ−→2KCl+3O2
[K=39,C=25.5 and O=16]
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Solution
2KClO3Δ−→3O2+2KCl2mole3mole2mole
Number of moles of O2 at S.T.P.=V(ml)22400=44822400=0.02mole
Mass of 1 mole of O2 = 32 grams
Mass of 0.02 mole of O2=32× 0.02 = 0.64 grams
Mass of KClO3=moles(n)×molecular weight=2× 122.5 = 245 grams
Weight of KClO3 to produce 3 moles of O2 = 245 grams
Weight of KClO3 to produce 0.02 moles of O2=245×0.023= 1.63 grams
Mass of KCl produced = Mass of KClO3-Mass of O2 produced =1.63−0.64=0.993 grams