the rate and extent of chemical change 6 Flashcards
what is the rate of reaction
how fast the reactants are changed into products
how can you find out the speed of reaction
you record the amount of product formed or the the amount of reactant used up
how can you tell what reaction is faster on a graph
the steeper the graph the faster but over time the reactants are used up so goes flat
How are reaction rates explained
by collision theory (the more collisions there are the faster the reaction but each particle needs enough energy to collide)
What does the rate of reaction depend on
Temperature
Surface area
Concentration or pressure
Catalyst
what happens to the particles when the temperature increases
particles move faster so collide more frequently
They also have more energy so they can break the bonds
what happens to the particles if you increase concentration
more particles in the same amount of water
what happens to the particles if you increase pressure
same number of particles occupies a smaller space
what happens to the particles if surface area is increased
increase surface area to volume ratio
for the same volume of solid the particles around it will have more area to work on.
what happens to the particles if you use a catalyst
speeds up the reaction without being used up
they decrease the activation energy and provide an alternate route.
what is a reversible reaction
a reaction that can go both ways
How do reversible reactions reach equilibrium
1) as reactants react their concentrations fall so the forward reaction will slow down
2) as more and more products are made and there concentrations increase the backward reaction speeds up
3) when the forward reaction is going at the same rate as the backwards one it has reached equilibrium.`
what is equilibrium
concentrations of reactants and products have reached a balance and wont change
when can equilibrium be reached
in a closed system where nothing can escape or get in
what happens when equilibrium lies to the right
the concentration of products is greater than the reactants
what happens when equilibrium lies to the left
the concentration of reactants is greater than the products
what is the energy transfer between endothermic and exothermic reactions in a reversible reaction
energy transferred from the surroundings by the endothermic is equal to the energy transferred to the surroundings exothermic
name an example of endothermic and exothermic reaction in a reversible reaction
heat blue hydrated copper and this drives off the water leaving white anhydrous copper(endothermic)
if you add water back it goes back to blue(exothermic)
what is La Chateliers principle
if you change the conditions of a reversible reaction at equilibrium, the system will try to counteract the change
what happens if you decrease the temperature in a reversible reaction
the equilibrium will move in the exothermic direction to produce more heat
this means you will get more products for exothermic and less for endothermic
what happens if you increase the temperature in a reversible reaction
the equilibrium will move in the endothermic direction to decrease it
this means you will get more products for endothermic and less for exothermic
what happens if you increase the pressure in a reversible reaction
the equilibrium tries to reduce it by moving in the direction where there are fewer molecules of gas
what happens if you decrease the pressure in a reversible reaction
the equilibrium tries to increase it by moving in the direction where there are more molecules of gas
what happens if you increase the concentration in a reversible reaction
the system tries to decrease it by making more products
what happens if you decrease the concentration in a reversible reaction
the system tries to increase it by reducing the amount of reactants
