Rates Of Reaction Flashcards
Why does increasing pressure/concentration increase the rate of reaction?
The reactant particles become more crowded
There is a greater chance of the particles colliding
The rate of reaction increases.
Why does increasing the surface area increase the rate of reaction?
More particles are exposed to other reactants
There are more collisions
The rate of reaction increases.
What is a catalyst?
A substance which changes the rate of reaction but is not used up and unchanged at the end of the reaction.
Why are catalysts specific to particular reactions?
Different catalysts catalyse different reactions, not all reactions have suitable catalysts.
What is activation energy?
The minimum energy needed for a reaction to occur when 2 particles collide.
How can you get a lower activation energy?
Use a catalyst.
How do you measure the rate of reaction?
Amount of reactant used OR product formed / time
What happens in reversible reactions?
The products can react to produce the original reactants again.
What happens in an endothermic reaction?
Energy is taken in from the surroundings. The surroundings then have less energy than they started with so the temperature falls.
What happens in exothermic reactions?
Energy is given out to the surroundings.
Give 3 examples of exothermic reactions.
Combustion, oxidation, neutralisation.
Give an example of endothermic reactions.
Thermal decompositions.
Give 3 ways to measure the rate of reaction.
Precipitation, change in mass, volume of gas given off.
Why does increasing temperature increase the rate of reaction?
The reactant particles move more quickly
they have more energy
the particles collide more often and more collisions are successful.
The rate of reaction increases.
