a piece of iron gain 10% mass due to partial rusting into fe2o3. what is the percentage of iron that has rusted

Question

cuanchi · Answer

I think you have to consider the relative percentage of mass of Fe and O in the Fe2O3
Fe=69.94%
O= 30.06%
100 x 30.06 /69.94=42.98%
That means a 42.98% change in mass from Fe -> Fe2O3 if 100% of the iron get rusted
But you have only a 10% increase in your mass
100 x10 /42.98 =23.27%
I am not sure about the calculations but I think it is a good approximation.

anonymous · Answer

well the solution seems right but i am not good with the percentage problems so i didn't quite got it well thanks though.