a measure of how quickly a reactant is used up or a product is formed
what is the equation for rate of reaction
quantity used or product made / time taken
what is the equation for mean rate of reaction
mean volume collected / time
what does a steeper line on a rate of reaction graph mean
faster the rate of reaction
what does a quick reaction mean the line will look like on a rate of reaction graph
becomes flat in the least amount of time
as volume increases what happens to the rate of reaction
decreases
what is activation energy
minimum amount of energy needed for a reaction to occur
what does the rate of chemical reactions depend on (collision theory)
-collision frequency of reacting particles
-energy transferred during collisions
what are the factors that affect the rate of reaction
-concentration/pressure
-temperature
-surface area
-add of a catalyst
what happens when temperature increases in the reaction
-particles have energy greater than or equal to the activation energy /more kinetic energy so move faster
-more frequent collision
-increases rate of reaction
what happens when the concentration increases in the reaction
-more particles in a given volume
-more frequent collisions
-increases rate of reaction
what happens when surface area is increased in the reaction
-more particles available to react at a given time
-more frequent collision
-increases rate of reaction
what is a catalyst
substance that speeds up a reaction without being used up itself, not part of overall reaction equation
how do catalysts works
by decreasing the activation energy needed for reaction to occur by providing an alternative pathway with lower activation energy
what do enzymes act as
biological catalyst, catalyse reactions in living things
how do you find the rate of reaction from a graph
find the tangent
what is a reversible reaction
when a reaction can reverse so that the products can change back to the reactants again
if a reversible reaction is endothermic in one direction what is it in the other direction
exothermic
what is the symbol for a reversible reaction
.
what happens to make a reaction reach its equilibrium
as the reactants concentration falls, the forward reaction will slowdown but as more product is made and concentration rises the backward reaction will speed up, they will eventually happen at the same rate, reaching equilibrium
what is equilibrium
when the forward and reverse reaction are occurring at the same rate in a closed system, no overall effect, concentrations won’t change
what is a closedsystem
where neither of the products or reactants can enter or leave
what does it mean if the equilibrium lies to the right
the concentration of the products is greater than that of the reactants
what does it mean if the equilibrium lies to the left
the concentration of reactants is greater than that of the product
what is le chateliers principle
the idea that if you change the conditions of a reversible reaction at equilibrium, the system will shift to counteract that change
what can le chateliers principle be used to predict
the effect of any changed you make to a reaction system
what happens when concentration of the reactants is increased in an equilibrium reaction
the position of the equilibrium will shift right to favour the products until the equilibrium is re-established
what happens when the concentration of the reactants is decreased in an equilibrium reaction
the position of the equilibrium will stay on the left to favour the reactants until the equilibrium is re-established
in what 2 cases can pressure effect the equilibrium
-if the molecules are gases
-if there are a different number of molecules (moles) on each side of the equation
what happens if the pressure is increased in the an equilibrium reaction
the position of the equilibrium shifts to the side with the fewest molecules of gas until the equilibrium is re-established
what happens if the pressure is decreased in an equilibrium reaction
the position of the equilibrium shofts to the side with the most molecules of gas until the equilibrium is re-established
what happens if the temperature of an equilibrium reaction is increased
the position of equilibrium will shift in the endothermic direction to lower the temperature by absorbing energy until the equilibrium is re-established, more products for the endothermic reactions
what happens if the temperature of an equilibrium reaction is decreased
the position of the equilibrium will shift in the exothermic direction to increase the temperature by releasing energy until the equilibrium is re-established, more products for the exothermic reactions