Question

A 5.0-gram sample of Fe(s) is to be placed in 100. milliliters of HCl(aq). Which changes will result in the fastest rate of reaction? 1. increasing the surface area of Fe(s) and increasing the concentration of HCl(aq) 2. increasing the surface area of Fe(s) and decreasing the concentration of HCl(aq) 3. decreasing the surface area of Fe(s) and increasing the concentration of HCl(aq) 4. decreasing the surface area of Fe(s) and decreasing the concentration of HCl(aq)

Answer 1

The answer is increasing the surface area of Fe(s) and increasing the concentration of HCl(aq). 

the rate of reaction can be increased if the interaction between the reactants in better. by increasing the surface area of a solid, such as Fe, you make more possible each molecule of Fe to interact with HCl. Also, by increasing the concentration of HCl, it mean there is more molecule of HCl to interact with Fe.