Potassium nitrate on strong heating decomposes as under:
2KNO3 2KNO2 + O2
(i) weight of potassium nitrite formed.
(ii) weight of oxygen formed when 5.05 g of potassium nitrate decomposes completely.
(K = 39, O = 16, N = 14)
Molar mass of KNO3 = [39 + 14 + (3 16)] g = 101 g mol−1
Molar mass of KNO2 = [39 + 14 + (2 16)] g = 85 g mol−1
According to balanced chemical reaction, two moles of KNO3 decomposes to form two moles of KNO2 and one mole of oxygen gas.
Number of moles of KNO3 decomposed = Number of moles of KNO2 formed = Number of moles of O2 formed
It is given that mass of KNO2 taken for the reaction is 5.054 grams.
(i) Weight of potassium nitrite formed = Number of moles Molecular weight of KNO2 =
(ii) Weight of oxygen formed = Number of moles Molecular weight of oxygen =