The Rate and Extent of Chemical Change
Rates of reaction
🔥 Mean Rate of Reaction = the amount of reactant used up / time taken 🔥
🔥 Mean Rate of reaction = the amount of product made / time taken 🔥
🔒 Required Practical 5 🔒
Factors affecting rate of reaction
COLLISION THEORY: for a reaction to take place particles must collide and they must collide with sufficient energy
If we increase the temperature particles gain more kinetic energy and therefore the frequency of successful collisions increase and the overall rate of reaction increase
If we decrease the surface area less area is exposed and therefore there is more frequent collisions and the overall rate of reaction decreases
NOTE Vice Versa if depending increase or decrease
If we increase the concentration/ pressure there are more particles per unit volume and the frequency of successful collisions increase an therefore the overall rate of reaction increases
if we add a catalyst the activation energy reduces and an alternative pathway is provided increasing the overall rate of reaction without being used up
Reversible Reactions & Dynamic Equilibrium
A reversible reaction is when the reactions of the product can react together to make the original reactants again!
Dynamic Equilibrium = this is the stage of the reversible reaction where the rate of the forward reaction is equal to the rate of the backward reaction
NOTE the amount of products & reactants stay the same
NOTE this can only happen in a close system
Le Chatelier's Principle
Le Chatelier's Principle states " If a change is made to the conditions of a system that is at equilibrium, then the system will respond to counteract the change
If the temperature is increased the position of equilibrium shifts in the direction of the endothermic process, until equilibrium is reached
If the temperature is decreased the position of equilibrium shifts in the direction of the exothermic process, until equilibrium is reached
If we increase the concentration of the reactants the equilibrium will shift to the right in favour of the products. the amount of products will increase and the yield will increase
If we decrease the concentration of the products the equilibrium will shift to the left in favour of the reactants. the amount of reactants will increase and the yield will decrease
In a reaction involving gases, if the the pressure is increased the position of equilibrium shifts in the direction of fewer gaseous molecules
In a reaction involving gases, if the the pressure is decreased the position of equilibrium shifts in the direction of more gaseous molecules
Measuring rates of reaction