Chemistry - Euan Flashcards
What is the rate of reaction?
The speed at which a chemical reaction takes place (the speed at which reactants turn into products).
Explain how there can be different units for measuring rate of reaction.
Change in mass (g/s), volume of gas formed (cm^3/s), formation of a precipitate
Measurement can involve either volume or mass depending on the method used.
List some factors that can affect the rate of a chemical reaction.
- Concentration of reactants
- Temperature
- Surface area of reactants
- Presence of a catalyst
- Constant stirring
What is collision theory?
Collision theory explains that a chemical reaction can only occur when particles collide.
How does temperature affect the rate of reaction?
Increasing the temperature makes molecules move faster, causing more frequent collisions making the reaction faster.
How does concentration/pressure affect the rate of reaction?
If you have a more concentrated area of molecules (concentration) or if they are squished together (pressure) they will collide more often, increasing the rate of reaction.
How does surface area affect rate of reaction?
If a solid is broken into peices its surface area becomes larger. This provides more sites for successful collisions to occur speeding up the reaction.
How does catalyst affect rate of reaction?
A catalyst lowers the activation energy needed for a reaction by providing a alternative pathway.This means successful collisions are more frequent which speeds up the rate of reaction without being used up.
What happens when temperature is increased?
Reactant particles start to move quickly and have more kinetic energy, this means they collide more often increasing rate of reaction.
How do you determine the rate of reaction at a specific time using a graph?
By drawing a tangent and dividing the height of the tanjent by the base of the tanjent
How can a surface area of a solid be increased?
A surface area of a solid can be increased by cutting it up or grinding it into a powder.
How does surface area affect the rate of reaction?
When increasing the surface area it increases the amount of available space for a reaction to occur.
How does collison theory explain the effect of surface area in a reaction?
Increasing the surface area increases the number of particles available to collide, increasing the frequency of collisons therefore speeding up rate of reaction.
How do you calculate the surface area to volume ratio.
Surface Area divided by Volume
How does changing concentration affects the rate of reaction?
If the concentration is increased this means that there are more particles moving together per unit, this means more collisions and an increased rate of reaction.
Using collision theory, how does changing the concentration alters the rate of reaction?
By increasing concentration, the chances for collisions between molecules are increased because there are more molecules per unit of volume.
