Final answer:
The effect of doubling the hydroxide concentration on the reaction rate depends on the rate law and order of the reaction with respect to hydroxide; it could double or quadruple the rate if the reaction is first-order or second-order with respect to hydroxide, respectively.
Step-by-step explanation:
To understand how the rate of a reaction will be affected if the concentration of hydroxide is doubled, we need to look at the rate law of the reaction. If the reaction follows an elementary rate law with respect to hydroxide, then doubling the hydroxide concentration would double the reaction rate. This is because the rate of an elementary reaction is directly proportional to the concentration of the reactants. However, without the exact rate law, we can't be sure of the effect, as different reactions have different rate orders with respect to their reactants.
For example, if the rate law is rate = k[OH-] then the reaction is first-order with respect to hydroxide, and doubling [OH-] would indeed double the reaction rate. If the rate law was rate = k[OH-]², a second-order reaction with respect to hydroxide, doubling [OH-] would quadruple the rate. The specific impact depends on the rate law and reaction order with respect to hydroxide.