To determine which options are NOT ways to speed up a chemical reaction, let's analyze each one:
a. Increasing the temperature of one of the reactants - This generally speeds up a reaction because higher temperatures provide reactant molecules with more kinetic energy, leading to more frequent and successful collisions. (This DOES speed up a reaction.)
b. Increasing the concentration of one of the reactants - Increasing concentration results in more reactant particles in a given volume, leading to more collisions and thus speeding up the reaction. (This DOES speed up a reaction.)
c. Decreasing the surface area of one of the reactants - A smaller surface area reduces the number of collisions between reactant particles, which can slow down the reaction. (This does NOT speed up a reaction.)
d. Decreasing the temperature of one of the reactants - Lowering the temperature generally slows down molecules, reducing the frequency and energy of collisions, which decreases the rate of reaction. (This does NOT speed up a reaction.)
Thus, the correct selections for options that are NOT ways to speed up a chemical reaction are:
c. decreasing the surface area of one of the reactants
d. decreasing the temperature of one of the reactants
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