When a single 1-gram piece of zinc is added to 3 m hydrochloric acid at 25°c, the reaction is slow. which procedure would most likely increase the rate of the reaction if the reaction were repeated? a. using 1 gram of powdered zinc b. using 1 m hydrochloric acid c. decreasing the temperature to 20.°c d. decreasing the concentration of the zinc

option A, using 1 gram of powdered zinc.

Explanation:

The rate of chemical reactions are affected by a number of factors, which you can summarize in this form:

1) Concentration of the reactants

The more concentrate are the reactants, more frequently they will interact (collide) and will be able to yield product. So, the higher the concentration the higher the rate.

This means using 1 M hydrochloric acid, as the option B states, instead of 3 M (stated for the original reaction) will slow down the reaction instead of increase the rate.

The same is valid for the option D. Decreasing the concentration of zinc will not increase the rate of the reaction, but will decrease it.

2) Surface area of the reactants

Increasing the surface area will permit that the reactants reach a faster intimate contact, occurring more of collisions per unit of time, and, consequently increasing the rate of the reaction.

Then, option A, using 1 gram of powdered zinc, i.e. the same amount stated for the original reaction, but with more surface area, will produce the desired effect of increasing the rate of reaction.

3) Temperature

Higher temperatures means that the kinetic energies of the reactants are higher and so the collisions will occur with more energy and the probability of effective collisions will increase. Decreasing the temperature will have the opposite effect (the rate of reaction will decrease).

Hence, the option C, decreasing the temperature to 20° C will not increanse the rate of the reaction.

3) Catalyst

Catalyst ares substances that modify the path of the reaction, decreasing the activation energy and, consequently, increasing the rate of reaction. Since, none of the statements indicates the use of catalyst, this is not an option.