Potassium nitrate decomposes on heating, producing potassium oxide and gaseous nitrogen and oxygen:

4KNO3(s)--> 2K2O(s) + 2N2(g) + 5O2(g)
To produce 56.6 kg of oxygen, how many (a) moles of KNO3 must be heated? (b) Grams of KNO3 must must heated?

2 answers

I worked this same problem a day or so ago. Frankly, I don't think the equation is correct.
Convert 63.7 kg of oxygen to grams. Then use stoichiometry and convert the grams of Oxygen to moles of Oxygen, then moles of KNO3 using the equation.

Calculations: 63.7 kg ---> 63,700 g. Divide by 32 grams of O2, then multiply by (4 moles KNO3/5 moles O2).

For the second part, take your answer from part A, and multiply it by 101.11 grams/mol of KNO3.