1) The area of contact between reacting solids
To maximize the contact between reactants we want to use starting reagents with large surface area. Consider the numbers for a 1 cm3 volume of a reactant
Edge Length = 1 cm
# of Crystallites = 1
Surface Area = 6 cm2
Edge Length = 10 mm
# of Crystallites = 109
Surface Area = 6 x103 cm2
Edge Length = 100
# of Crystallites = 1018
Surface Area = 6 x 106 cm2
Pelletize to encourage intimate contact between crystallites.