The rate and extent of chemical change Flashcards
what are the 2 ways of measuring rate of reaction?
how fast reactants are used up OR how fast products are being formed
what are the equations for average rate of reaction?
quantity of products formed/ time OR quantity of reactants used/ time
what are the factors affecting rate of reaction?
temp, concentration/ pressure, surface area, catalyst.
what is collision theory?
in order for particles to react, they have to collide with each other with sufficient energy.
what does the rate of collision theory depend on?
amount of energy particles have and the frequency of collisions.
why does rate of reaction increase if energy particles have is higher?
they have more energy to transfer during collisions.
why is frequency of collisions important for collision theory?
the particles will collide more so there will be more successful collisions.
how does temperature increase rate of reaction?
as temp increases particles gain more energy which means they move faster, so they collide more frequently. they will also collide with more energy. higher rate of successful collisions
how does increased concentration/ pressure increase rate of reaction?
more particles per unit of volume means collisions will be more frequent. this means increased successful collisions
how does increasing the surface area (to volume ratio) increase the rate of reaction?
much higher area where collisions can take place meaning collisions frequency would increase.
what is a catalyst?
substances that speed up a reaction but are not used up in the reaction themselves.
how does a catalyst increase the rate of reactions?
creates an alternative reaction pathway with a smaller activation energy, meaning a higher proportion of successful collisions.
what are the most common catalysts?
transition metals (e.g. cobalt and nickel) and enzymes.
what is the equilibrium of reversible reactions?
concentrations of reactants used up and products won’t change anymore SO both reactions are still happening but they cancel each other out
how does the position of equilibrium change?
when there are more products the equilibrium lies to the right but more reactants and less products it lies to the left.
how does adding heat change the equilibrium?
it encourages the forward reaction meaning we will have more products. this means the position of equilibrium will move to the right.
what is a closed system?
a sealed environment from which none of the reactants or products can escape.
are reversible reactions endothermic or exothermic?
they are exothermic one way and endothermic the other way.
what is le chatelier principle?
change in conditions of a reversible reaction then the position of equilibrium will shift to try to counteract the change
what 3 factors affect position of equilibrium?
temp, concentration and pressure.
if there is an increase in pressure which side will the equilibrium move to?
smaller number of gas molecules
