Year 9 Science EOY(chemistry-how fast) Flashcards
(27 cards)
Recall a definition for rate of reaction.
Rate of reaction is How fast a chemical reaction happens.
What is the collision theory
It states that chemical reactions occur when particles collide with enough energy and the correct allignment. Only these effective collisions lead to a reaction.
Explain how there can be different units for measuring rate of reaction.
There are different units for measuring rate of reaction because of different materials used for example, how long the reaction takes, the mass of the variables.
Eg: seconds, minutes,mass, volume, concentration
List some factors that can affect the rate of a chemical reaction.
Concentration of Reactants, temperature, surface area, catalysts, pressure(for gases)
Explain using collision theory how temperature
concentration/pressure
Describe how temperature affects the rate of reaction.
Move faster, leading to more frequent collisions.
Collide with greater energy, making it more likely to overcome the activation energy barrier.
Describe how surface area of a solid can be increased.
Break it into smaller pieces (e.g., crushing or grinding it into powder)
Spread it out more thinly (e.g., flattening or slicing)
This exposes more particles on the surface, allowing more collisions with reactants, which speeds up the reaction.
Describe how changing the surface area changes the rate of reaction.
Increasing the surface area means more particles of the solid are exposed and available to collide with reactant particles.
This leads to more frequent collisions per unit time.
State how collision theory explains the effect of surface area on the rate of reaction.
According to collision theory, increasing the surface area of a solid exposes more particles to collide with reactant particles. This leads to more frequent collisions, increasing the chance of successful collisions with enough energy and proper orientation. As a result, the rate of reaction increases when surface area is increased.
Describe how changing concentration affects the rate of reaction.
Increasing concentration means there are more reactant particles in the same volume.
This leads to more frequent collisions between particles.
More collisions increase the chance of successful collisions with enough energy.
Therefore, the rate of reaction increases as concentration increases.
Use collision theory to explain how changing the concentration alters the rate of reaction.
When concentration increases, there are more particles of reactants in the same volume.
This causes particles to collide more frequently.
Describe how changing pressure of gaseous reactants affects the rate of reaction.
Increasing the pressure compresses the gas, so the gas particles are closer together.
This leads to more frequent collisions between the gas particles.
More collisions increase the chance of successful collisions with enough energy.
Use collision theory to explain how changing the pressure of gaseous reactants alters the rate of reaction.
According to collision theory, increasing the pressure of gaseous reactants pushes the particles closer together, so they collide more often. More frequent collisions mean a higher rate of reaction.
Describe what the activation energy of a reaction is.
Activation energy is the minimum amount of energy needed for a reaction to start.
