A large piece of iron was reacted with an acid. What would happen to the rate of the reaction had the large piece been finely divided into smaller pieces?

For a reaction to occur there must be effective collision between the reactant molecules. When the iron or the reactant particles are finely divided that increases the surface area exposing more reactant particles on the surface and increase the rate of intermoleculer collision. The greater effective collision between the reactant molecules the faster will the reaction occur.

The reaction occurs in a similar way as magnesium does, but much less vigorous. Strong heating is required to make iron powder burn in oxygen. The reaction gives out a yellow showery sparks and produces a black solid. iron reacts with dilute hydrocloric acid to give iron chloride and hydrogen gas.