Question

select the correct collision theory explanation for changing the rate of the given chemical reaction. refrigerate food to keep it from spoiling. add inert water to a reaction solution. compress the air/fuel mixture inside an engine cylinder with a piston. raise the boiling point of water with a pressure cooker. grind a metal into a fine powder.

Explanation:

1. Refrigerating food: Lowering temperature reduces the kinetic energy of reacting molecules (such as those in spoilage - causing reactions), decreasing the frequency and energy of effective collisions, thus slowing down the reaction rate.
2. Raising boiling point with a pressure - cooker: Increasing pressure increases the temperature at which water boils. Higher temperature increases the kinetic energy of reacting molecules, increasing the frequency and energy of effective collisions, speeding up reactions (e.g., cooking food faster).
3. Adding inert water to a reaction solution: Diluting the reactant concentration with inert water decreases the number of reactant molecules per unit volume. This reduces the frequency of effective collisions, slowing down the reaction rate.
4. Grinding a metal into a fine powder: Increases the surface area of the metal. More surface - exposed molecules are available for collisions, increasing the frequency of effective collisions and speeding up the reaction rate.
5. Compressing the air/fuel mixture in an engine cylinder: Increases the concentration of reactant molecules (air and fuel). Higher concentration leads to a greater number of molecules per unit volume, increasing the frequency of effective collisions and speeding up the combustion reaction.

Answer:

1. Refrigerating food: Decreases reaction rate by reducing collision frequency and energy.
2. Raising boiling point with a pressure - cooker: Increases reaction rate by increasing collision frequency and energy.
3. Adding inert water to a reaction solution: Decreases reaction rate by reducing collision frequency.
4. Grinding a metal into a fine powder: Increases reaction rate by increasing collision frequency.
5. Compressing the air/fuel mixture in an engine cylinder: Increases reaction rate by increasing collision frequency.