Question

If .50 grams of oxygen were lost during the thermal decomposition of a sample of KClO_3, how many grams of KClO₃ decomposed?

2 KClO₃ --->(2 KCl decomposed) + 3O₂

Answer 1

Hi,

If we know the quantity of grams of oxygen that decomposes from the compound KClO3, through the stoichiometric coefficients of the reaction we can make a relationship and consider that 2 moles of KClO3 produced 6 moles of oxygen (3 by sub-index 2) to obtain the moles of KClO3. To know the grams from the moles, multiply by the molecular weight of KClO3 set at a value of 122.55 g / mol.


First to be able to make the relationship between moles, you must pass 50 grams of oxygen to moles. Molecular weight O, 16 g/mol: 





Finally, the necessary grams of the KClO3 reagent are known, to produce 3,125 mol of O:



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