In the spacecrafts of NASA the oxygen required for the astronauts is obtained from the chemical reaction $$\text{KClO}_3(s) + \text{Fe}(s) \rightarrow \text{O}_2(g) + \text{KCl}(s) + \text{FeO}(s)$$. The requirement of $$\text{O}_2$$ per astronaut per day is 500 L as measured at 1 atm and 300 K. The minimum mass of $$\text{KClO}_3$$, whose molar mass is 122.5 g per $$mol^-1$$, needed for two astronauts to be in the spacecraft for ten days in a space mission is