C8 Rates and Equilibrium
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what is the rate of reaction like at the beginning of the reaction?
the reaction is very fast. there is a lot of product being made in a short amount of time
why is the rate of reaction fast at the beginning of the reaction?
there are a lot of reactant molecules which can collide and form the products
why does the rate of a reaction decrease over time?
a lot of the reactant molecules have already reacted and produced the products this means there are less molecules to react and form the products
why does a reaction stop?
all the reactant molecules have reacted
how can you measure the rate of a reaction?
measure the amount of product formed or the amount of reactant used over time
how do you work out the mean rate of reaction?
quantity of product formed or reactant used / time taken
what does the slope of a graph give? (when measuring the amount of product formed/reactant used over time)
the rate of reaction
if a graph has a curved line, what does this mean?
the slope is constantly changing so the rate is constantly changing
what does a tangent do?
gives the rate of the reaction at a specific point when the graph is a curve
what are the ways you increase the rate of reaction in terms of collisions?
the energy of collisions the number of collisions
what are the ways you increase the rate of reaction?
increase: concentration temperature pressure surface area catalyst
why does an increase in surface area, pressure and concentration increase the rate of reaction?
there are a greater number of collisions of the reactions likely to happen.
why does a catalyst increase the rate of reaction?
it increases the likelihood of collisions as it provides an easier path for the reactants to meet
how does temperature increase the rate of reaction?
it increases the energy of collisions and the likelihood of collisions happening
what is a reversible reaction?
a reaction in which teh products can re-form the reactants
what is a fact about the energy released and taken in in a reversible reaction?
the amount of energy transferred to the surroundings in one direction is equal to the energy transferred back in the opposite direction
what are the properties of the forward and reverse reactions of a reversible reaction in terms of energy?
one is exothermic the other is endothermic
what is dynamic equilibrium?
in a reversible reaction, the rate of the forward reaction equals the rate of the reverse reaction
what is Le Chatelier’s principle?
when a change in conditions is introduced to a system at equilibirum, the position of equilibrium shifts to cancel out the change
what happens if pressure is increased in terms of a reversible reaction? with gases
the reaction that has fewer molecules is favoured
what happens if pressure is decreased in terms of a reversible reaction? with gases
the reaction with the greater number of molecules is favoured
what happens if the temperature is increased with reversible reactions?
the endothermic reaction is favoured
what happens when the temperature is decreased with reversible reactions?
the exothermic reaction is favoured