A sample of pure iron powder (100.00 g) was put in a 1000-mL beaker and exposed to air. Half a year later, the beaker together with the partially rusted iron in it weighed 282.30 g. Soon afterwards, 500.00 g dilute sulfuric acid (2.00 M) was added to the beaker.
After 1 hour, all the solid disappeared, and the mixture cooled to room temperature, the beaker together with its content weighed 781.00g.
What percentage of the original iron had turned into rust?
Atomic mass of Fe: 55.85