1. ## collision theory ror

explain how the five rate of reaction factors alter the rate of reaction using collision theory

2. ## Re: collision theory ror

1. Temperature - higher temperature means more kinetic energy, so molecules collide faster and more often (also more of them will have the required activation energy), therefore increasing RoR.

2. Surface area - higher surface area means more particles are exposed to collisions, so collisions happen more often -> higher RoR

3. Concentration/pressure - higher concentration/pressure means more particles in the same space -> collisions happen more often -> higher RoR

4. Catalyst - catalysts lower activation energy barrier, so more particles will have enough activation energy so successful collisions happen more often -> higher RoR

5. Mixing - mixing imparts more kinetic energy to the particles, see 1.

3. ## Re: collision theory ror

Originally Posted by dgt20
explain how the five rate of reaction factors alter the rate of reaction using collision theory
Hi, here are my notes for this area:

For a reaction to occur, the collision theory states: that the reactant particles (atoms, molecules, ions) must react with sufficient energy to overcome activation energy barrier (correct collisional energy), as well as the correct collisional orientation (this just means like if an OH on a molecule is the thing reacting with say a O then those two sides need to collide and it wouldn't work if the first one collided on say the H side of ethanol with the O from the other atom).

Nature of reactants - Each reaction has its own activation energy.

Concentration - An increase in reactant concentration means that there is an increase in the number of reactant particles per unit volume. This will lead to an increased chance of collisions, leading to an increase in the number of collisions per unit time. (This relates to pressure because it essentially increases the concentration of the reactants because they are brought closer together in a smaller volume)

Surface Area - If the surface area of a reactant is increased, more of the reactant molecules are exposed to collision. Since particles must collide to react, this will lead to an increased rate of reaction.

Temperature - Increasing temperature speeds up the rate of reaction by providing kinetic energy through the conversion of thermal (heat) energy to kinetic energy increases to reactants and products, allowing more molecules to possess the correct collisional orientation and energy to overcome the EA (activation energy barrier) (therefore there is more successful collisions).

Catalyst: A catalyst is a substance that increases the rate of reaction without being consumed. Catalysed reactions have lower activation energy, than similar uncatalysed reactions. Catalysts work by allowing for an alternative mechanism for the reaction. Effectively this means that more colliding particles will have the required amount of energy for the reaction to occur. The enthalpy of the reaction remains the same. There are two types of catalysts: homogeneous and heterogeneous. Enzyme is a substance produced by a living organism which acts as a catalyst to bring about a specific biochemical reaction.

Breaking big lumps of solid into smaller pieces: This increases the surface area of the solid and consequently, the rate of collision increases as more particles of the solid are exposed to the other reactants, increasing the rate of reaction.

4. ## Re: collision theory ror

I used this acronym to memorise it, even use it in uni still. Its called COPAT, easy way to remember them.

C - Concentration
O - Orientation and Size
P - Particle Size (same as surface area)
A - Activation Energy (Nature of reactants)
T - Temperature

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