It is possible to remove some impurities from liquids by adding to the liquid colloidal particles that will react with the impurities, then removing the colloidal particles.

a. Assuming that the reaction between colloidal particles and impurities is fast when they come in contact, write down an expression for reaction rate in terms of the appropriate concentrations.

b. If the colloidal particles can react with any number of impurity molecules (in other words, they are not consumed), derive an expression that could be used to estimate the concentration of colloidal particles that would be required to remove 99% of the impurity molecules in a given time, .

Clearly state any assumptions you make. The colloidal particles may be considered to be small enough to assume they diffuse like a molecule and have a concentration given in particles per volume.