Rate Of Reaction Flashcards
What 3 things can we measure when investigating rate of reaction?
Change of Volume - with a gas syringe or burette
Change of Mass - with a mass balance
Precipitate - Time for a cross under a beaker to disappear
When explaining Reaction rates always talk about …
Particles and collisions per second
Rate of reaction is affected by ……
Size of particle (surface area) Temperature Concentration of a solution Pressure on a gas Catalyst
Define a catalyst
A substance which increases the rate of reaction but remains chemically unchanged at the end of the reaction
Why do small particles have faster rate of reaction?
The particles have a larger surface area
More collisions per second
Why is custard powder or coal dust so explosive?
Tiny particles have very large surface area so very fast rate of reaction.k
What is concentration?
The number of particles in a given volume.
Why does high concentration in a solution lead to faster rate of reaction?
More particles in a given volume so more collisions in a given time
What is the relationship between rate of reaction and concentration?
Rate of reaction is directly proportional to concentration
What happens to concentration during a reaction?
Concentration decreases.
Fewer particles in a given volume
Fewer collisions per second
Rate of reaction decreases with time
Why does high pressure on a gas lead to faster rate of reaction?
High pressure means more particles in a given volume
So more collisions per second
So faster rate of reaction
What is activation energy?
Particle energy needed for a reaction to take place
Increasing in temperature increases rate of reaction. Why?
Higher temp means molecules have more kinetic energy and move faster
More molecules above activation energy
More collisions in a given time
How do catalysts work?
Lowers the activation energy
So a greater proportion of collisions result in a reaction
