State the equation to find the rate of reaction
amount of reactant used / time
OR
amount of product formed / time
How do you find the rate of reaction graphically?
draw a tangent to the line of best fit
What factors affect the rate of reaction?
- Concentration
- Pressure
- Surface area
- Temperature
- Catalysts
Define collision theory
chemical reactions can occur only when reacting particles
collide with each other and with sufficient energy
Define activation energy
the minimum amount of energy that particles must have to
react
What does increasing the concentration of reactants in a solution do to the rate of reaction?
increases the frequency of collisions and so increases the rate of reaction
What does increasing the pressure of reaction gases do to the rate of reaction?
increases the frequency of collisions and so increases the rate of reaction
What does increasing the surface area of solid reactants do to the rate of reaction?
increases the frequency of collisions and therefore increases the rate of reaction
What does increasing the temperature do to the rate of reaction?
increases the frequency of collisions and makes the collisions more energetic, and so increases the rate of reaction
What are catalysts?
- substances that speed up chemical reactions without being changed or used up
- enzymes act as catalysts in biological systems
- catalysts are not included in the equation for a reaction
What do catalysts do to the activation energy, how?
- catalysts decrease the activation energy; this increases the proportional of particles with energy to react
- catalysts provide a different pathway for a chemical reaction that has a lower activation energy
What is a reversible reaction?
where the products of the reaction can react to produce the original reactants
What 3 points make up a dynamic equilibrium reaction?
- the rate of the forward reaction is equal to the rate of the backwards reaction
- concentration of reactions + products remain constant
- closed system
State Le Chatelier’s Principle
When an external factor (e.g: temperature/pressure) is changed on an equilibrium system, the equilibrium will oppose the change and shift back to it’s original position.
What happens if we increase the concentration of the reactants in an equilibrium reaction?
- the system wants to decrease the concentration of the reactant
- therefore equilibrium shifts to the right, making more of the product.
What happens if we decrease the concentration of the reactants in an equilibrium reaction?
- the system wants to increase the concentration of the reactants
- equilibrium shifts to the left and makes more reactant.
What happens if we increase the gas pressure in an equilibrium reaction?
- the system wants to decrease the gas pressure of the system
- the eq. shifts to the side with less moles of gas, and makes more of the substance on that side
What happens if we decrease the gas pressure in an equilibrium reaction?
- the system wants to increase the gas pressure
- eq. shifts to the sides with more moles of gas, and makes more of the substance on that side
What happens if we decrease the temperature in an equilibrium reaction?
- the system wants to increase the temperature
- eq. shifts in the exothermic direction
What happens if we increase the temperature in an equilibrium reaction?
- the system wants to decrease the temperature
- eq. shifts in the endothermic direction
if the energy change of the forward reaction is negative, is the forward reaction endo or exothermic?
exothermic
State the equation linking moles, relative formula mass and mass
mass = mr x mole
Equation linking concentration, volume and mass?
mass = concentration x volume
How to calculate percentage yield?
amount of product produced/maximum amount of product possible
