Rates of Equilibrium Flashcards
How to find out the rate of reaction is
How quickly reactants are used up as they make products
OR
How quickly products of reaction are made
Three techniques to collect type of data in experiments
1) Measure the rate at which the mass of a reaction mixture changes if the reaction gives off a gas
Put on scale, reaction mass decreases if gas is given off
2) Use gas syringe to see increasing volume of gas given off
3) Decreasing light passing through solution = cloudy
Mean rate of reaction equation
Mean rate of reaction = quantity of reactant used / time
OR
Quantity of product formed / time
Collision theory
Particles need to collide with enough energy to cause a reaction
What is activation energy
Minimum amount of energy particles reactants must have before they can react
What affects the rate of reaction and how?
Big surface area
Size of pieces of solid affects the rate of the reaction
Particles around solid can only affect surface of reactant
Small lumps or powder have larger surface area surrounded by solution = more particles exposed
Why does raising the temperature increase the rate of reaction?
Particles collide more often
Particles collide with more energy
How do particles collide more frequently?
Heat substance
Energy transferred to its particles
Particles move around faster
Particles collide more frequently, have more chances to react
How do particles collide with more energy?
Particles move around more quickly = have more energy
Collisions are more energetic
Rule of greater collisions
An increased proportion of particles exceeding the activation energy has a greater effect on rate than increased frequency of collisions
Effect of concentration
More particles of reactants moving around in same volume of solution
More crowded together so more likely they will collide
Increased frequency = faster reaction
Effect of pressure
Squashes gas particles more closely together
More particles of gas in given space
Increases chance to collide and react
Produces more frequency collisions
What does a catalyst do
Changes rate of reactions
Products do not change
Speeds up rate of a chemical reaction by reducing energy
Catalysts forms
Different catalysts needed for different reactions
Usually in form of powders, pellets or fine gauzes = biggest possible SA:V
How catalysts work
Do not increase collision frequency
Increase rates of reaction by providing an alternative reaction pathway to products
higher proportion of reactant particles have sufficient energy to react