Question

Moist iron wool was inverted over water. The set up was left to stand for 2 days

1. Explain whether rusting is a physical or chemical reaction
2. Write an expression using X and Y to show the percentage of Oxygen 
3. What would be the effect of using a larger piece of iron wool? Explain.

Answer 1

1. Chemical change /new substance formed
2. Oxygen = ^{(Y – X) x 100}/_Y
3. No change  since % of oxygen is the same OR Vol. of O2 is fixed