- Collision theory states that reaction rates increase with more frequent molecular collisions.
- Reducing the volume of the container (placing reactants in a smaller container) increases the concentration of reactant gas molecules.
- Increased concentration forces molecules closer together, which directly increases the frequency of collisions.
- Therefore, the correct way to speed up the collisions is to place the reactants in a smaller container.
Explanation
- Analysis of Reaction Kinetics and Collision Theory
The chemical reaction for the production of water is given by the balanced equation:
\[2H_2(g) + O_2(g) \rightarrow 2H_2O(g)\]
According to collision theory, the rate of a chemical reaction depends on the frequency of successful collisions between reactant molecules. To increase the frequency of collisions between hydrogen (\(H_2\)) and oxygen (\(O_2\)) molecules, we need to consider factors that influence the movement and spacing of gas particles. Increasing the concentration (number of molecules per unit volume) significantly increases the probability that molecules will bump into each other.
- Evaluating Methods to Increase Collision Frequency
We evaluate the provided options based on how they affect the collision frequency:
- 'Use a less-intense source of heat': Lowering the temperature decreases the average kinetic energy of the molecules, meaning they move slower. Slower-moving molecules collide less frequently, and fewer collisions will have the energy to overcome the activation energy barrier.
- 'Reduce the concentration of the reactants': Reducing the concentration means there are fewer molecules in the same amount of space, which naturally leads to fewer collisions.
- 'Place the reactants in a smaller container': Reducing the volume of the container increases the concentration of the reactants. When the same number of molecules is forced into a smaller space, they are closer together and are far more likely to strike one another, thus increasing the collision frequency.
- 'Maintain the same temperature of the reactants': This does not change the frequency of collisions compared to the initial state, so it does not speed up the reaction.
- Conclusion and Final Selection
Based on our evaluation, placing the reactants in a smaller container increases the concentration of the reactant gases. As the molecules are packed more tightly, the frequency of collisions increases, leading to a faster reaction rate and more efficient production of water. Therefore, this is the correct method.
Examples
Imagine you are trying to catch fireflies in a jar. If you use a very large, open field, the fireflies are spread out and it is difficult to catch them. However, if you gather all those fireflies into a small, enclosed jar, they are suddenly packed tightly together. Now, every time you reach into the jar, you are much more likely to encounter one. This is exactly like increasing the pressure or decreasing the volume of gas reactants in a chemical reaction: by confining the molecules to a smaller space, you force them to 'run into' each other much more often, which speeds up the rate at which they react!