Up
to now, at least one of the reactants has been in either the
liquid or gas state.
With the particles of one of the substances moving around,
it means there will be collisions with the particles of
the other substance.
If two substances in the solid state are mixed together, the
particles are stuck with their own kind in 'lumps’ –
they cannot get at each other very well.
A way to get round this is to dissolve the substances in water
first and then mix the solutions.
