posted by Howard .
Which of the following is the BEST explanation for why a catalyst speeds up a reaction?
A) The catalyst increases the concentration of the products
B) The catalyst decreases the total pressure in the container.
C) The catalyst raises the temperature of the reaction mixture.
D) The catalyst lowers the activation energy required for the reaction to occur.
E) The catalyst increases the probability that a collision will occur by taking up space in the container.
D is clearly the correct answer. In a sense, activation energy is related to temperature and at higher temps, molecules move faster and therefore have more frequent collisions. Catalysts lower the activation energy by bringing substrates together.