Controlling The Rate Flashcards
What is the equation for relative rate
Rate = 1/t
(Units are as follows depending on question; S -1/ min -1)
What does collision theory state
For a chemical reaction to take place, reactants must collide with the correct geometry and enough energy to overcome Ea
How does increasing concentration affect the rate of reaction
The greater the concentration, the greater the number of particles, the greater the opportunity for collisions meaning a greater number of successful collisions and therefore faster rate
How does an increase in pressure impact the rate of reaction (only relevant for gaseous reactions)
Increasing pressure means particles have less space to move, hence a greater opportunity for collisions, the greater the number if collisions means a greater number of successful collisions and therefore a faster rate of reaction
How does a decrease in particle size affect the rate of reaction
Particle size decrease leads to a greater surface area which allows for a greater number of collisions which means a greater number of successful collisions and therefore a faster rate of reaction.
What is temperature
Its a measure of average kinetic energy of the particles in a substance
What effect does an increase in temperature have on the rate of reaction
The greater the temp the greater the kinetic energy of particles the greater the force of the collisions. More particles have the energy to overcome the Ea. Therefore increasing the rate of reaction
What is the enthalpy change
Difference between products and reactants
What enthalpy change value will exothermic/ endothermic reactions have
Exothermic-negative
Endothermic-positive
What is activation energy (Ea)
The minimum kinetic energy required by colliding particles to form an activated complex.
What is an activated complex
An unstable arrangement of atoms formed at the maximum of the potential energy barrier, during a reaction
How do catalysts effect the rate
A catalyst provides an alternative reaction pathway with a lower activation energy and hence increases the rate
