Which of the following is NOT a way to speed up a chemical reaction? (Select all that apply)
a
decreasing the temperature of one of the reactants
b
increasing the concentration of one of the reactants
c
decreasing the surface area of one of the reactants
d
increasing the temperature of one of the reactants
a and c are not ways to speed up a chemical reaction.
The answer to the question is:
c) decreasing the surface area of one of the reactants.
To determine which of the given options is NOT a way to speed up a chemical reaction, we need to understand the factors that affect the rate of a reaction.
a. Decreasing the temperature of one of the reactants:
This option is a valid method to slow down a chemical reaction. Lowering the temperature decreases the kinetic energy of the reactant molecules, reducing their frequency of collisions and lowering the reaction rate.
b. Increasing the concentration of one of the reactants:
Increasing the concentration of a reactant increases its presence in the reaction mixture. This leads to a higher frequency of collisions between reactant molecules, resulting in an increased reaction rate. Thus, this option speeds up the reaction.
c. Decreasing the surface area of one of the reactants:
Decreasing the surface area of a reactant reduces the area available for reactant molecules to interact with each other. This restricts the number of collisions and leads to a slower reaction rate. Hence, this option can also slow down the reaction.
d. Increasing the temperature of one of the reactants:
Increasing the temperature of a reaction increases the kinetic energy of the reactant molecules. This enhances their collision frequency and promotes the formation of effective collisions (ones with sufficient energy for a reaction to occur). Hence, increasing temperature accelerates the reaction rate.
So, the answer is option a) decreasing the temperature of one of the reactants, as it is the only option that does not speed up a chemical reaction.