What is the purpose of finding oxidation states in the half-reaction method for balancing equations?
to use as coefficients in the final equation
to identify the half reactions for the equation
to make sure the equation is balanced electrically
to find the electrons that are needed for each side of the equation

Consider a culture medium on which only gram-positive organisms such as staphylococcus aureus colonies can grow due to an elevated nacl level. a yellow halo surrounds the growth, indicating the bacterium fermented a sugar in the medium, decreasing the ph as a result and changing the color of a ph indicator chemical. this type of medium would be referred to as a differential and enrichment culture.