To increase the rate of collisions between the reactants in the given reaction:
[tex]\[
Mg + 2HCl \rightarrow MgCl_2 + H_2
\][/tex]
we need to consider the factors that influence collision frequency according to the collision theory. The collision theory states that for a chemical reaction to occur, reactant particles must collide with sufficient energy and proper orientation. The factors that can increase the rate of collisions include:
1. Increasing the concentration of reactants: Higher concentration means more reactant particles are available per unit volume, which increases the likelihood of collisions.
2. Increasing the temperature: Higher temperature increases the kinetic energy of the reactant molecules, causing them to move faster and collide more frequently and with greater energy.
3. Catalysts: Catalysts can provide an alternative pathway with a lower activation energy for the reaction, thus increasing the rate of reaction.
Given the options:
- A. Increase the concentration of [tex]\( H_2 \)[/tex] in the reaction mixture.
- Increasing the product concentration ([tex]\( H_2 \)[/tex]) does not alter the rate of reactant collisions.
- B. Decrease the temperature of the reactants in the reaction mixture.
- Decreasing the temperature would decrease the kinetic energy and reduce the rate of collisions.
- C. Increase the concentration of [tex]\( Mg \)[/tex] in the reaction mixture.
- Increasing the concentration of [tex]\( Mg \)[/tex] will increase the number of [tex]\( Mg \)[/tex] atoms available to collide with [tex]\( HCl \)[/tex] molecules, leading to an increased rate of collisions.
- D. Decrease the temperature of the entire reaction mixture.
- Similar to option B, decreasing the temperature will reduce the kinetic energy and the collision frequency.
- E. Decrease the concentration of [tex]\( HCl \)[/tex] in the reaction mixture.
- Decreasing the concentration of [tex]\( HCl \)[/tex] would result in fewer [tex]\( HCl \)[/tex] molecules, thereby reducing the rate of collisions.
The correct answer is:
C. Increase the concentration of [tex]\( Mg \)[/tex] in the reaction mixture.
This will increase the rate of collisions between the reactants, leading to a faster reaction rate.
