Potassium nitrate decomposes on heating, producing potassium oxide and gaseous nitrogen and oxygen: 4KNO3(s) → 2K2O(s) + 2N2(g) + 5O2(g) to produce 71.8 kg of O2, how many...
a) Moles of KNO3 must be heated?
b) Grams of KNO3 must be heated?
First, let's calculate how many moles of oxygen are produced. This can be obtained by converting kg to g then dividing by the molecular mass of O2, 71.08 kg x 1000 g / 32.0 = 2221 moles of O2. As the moles of KNO3 is related to the moles of O2 in the ratio of 4 to 5, The number of moles of KNO3 required is given by
4 moles KNO3/ 5 moles O2 x 2221 moles O2 = 1777 moles KNO3 must be heated. Now convert the moles KNO3 to grams by multiplying the moles of KNO3 by molecular mass of KNO3 (101 g). This gives
1777 moles KNO3 x 101 g/mole = 179777 g.
Check my math and report to the correct number of sig figs. which should be 3.