Controlling the Rate Flashcards
Relative rate
1 / t
In collision theory, what must reactant particles collide with?
- energy greater than / equal to the activation energy
- the correct collision geometry or angle
What is the activation energy
The energy needed by colliding particles to form an activated complex.
Define the activated complex
An unstable arrangement of atoms, intermediate between reactants and products, formed at the maximum of the potential energy barrier in a reaction
What is Ea in potential energy graph
Line between peak and reactant level
Where is activated complex in potential energy graph
Peak of the curve
Define temperature
The measure of the average kinetic energy of all of the particles in a substance
10 degree rise in temp effect on rate
Doubles rate
Explain temperature
Inc temp increases average kinetic energy of the particles and so a greater proportion of reactant particles collide with energy greater than or equal to the activation energy. Since more particles have the minimum energy needed to react, there are more collisions and so more successful collisions, therefore the rate is faster
What is a catalyst
a substance that speeds up a chemical reaction and can be recovered chemically unchanged.
Biological catalyst
Enzyme
What can a catalyst provide
an alternative reaction pathway with a lower activation energy, allowing the reaction to take place at a lower temperature
Activation energy with a catalyst compared to without
the activation energy without a catalyst is higher than the reaction without one.
3 catalyst industry examples
Iron - makes ammonia in the haber process
Platinum - manufactures nitric acid in the ostwald process
Nickel - makes margarine by hardening the oils
Enthalpy change
the energy difference between the products and reactants and is the overall enthalpy change for a reaction.
