Powder reactants react faster than lumps.

• A. True
• B. False
• C. Sometimes
• D. Not related

Answer: (A)

Surface area and collision frequency determine reaction rate. When a solid reacts with another substance, the reaction occurs at the surface where the particles meet. A powder has a much larger surface area exposed to the other reactant than a lump, so there are more opportunities for collisions to happen per second. More frequent successful collisions speed up the overall rate of reaction. If the solid needs to dissolve to react, the powder will also dissolve more quickly, exposing fresh surface sooner and accelerating the reaction. Under the same conditions, this means the powder reacts faster than the lump.