rates of reaction Flashcards
what is the rate of reaction?
the rate of reaction is how quickly the products are formed or how quickly the reactants are used up
why do you measure reaction rates?
we measure reaction rates so we can learn what influences them and how to control them
what is the equation for reaction rate?
Reaction Rate = Change in substance / Time
how do chemical reactions occur?
when particles of a reactant collide with enough energy to react
what is collision energy?
collisions will only occur in a reaction if their is enough collision energy.
what is collision theory?
for a reaction to happen between 2 substances the particles have to collide with enough energy for existing bonds to break and new bonds to form
name 2 reasons why a reaction rate may increase.
- the chance of 2 particles colliding increases which happens when you change the conditions of:
- concentration of solution
- pressure of a gas
- surface area of a solid - the energy the particles collide with increases
why does the rate of reaction slow down over time and stop?
as the reaction progresses there are less reactant particles so there are less frequent collisions
key points of concentration.
- increasing the concentration of an acid whilst keeping all other conditions the same will increase the rate of reaction
- the amount of product stays the same if the acid is in excess
- the amount of product will change in line with the concentration if the solution is the controlling factor
how does temp affect rate of reaction
it increases the rate of reaction
how can you tell if there is a correlation between temp and rate of reaction?
you could take measurements across a wider range of temps
HOW does increasing temp increase the reaction rate?
the higher the temp the more kinetic energy so the particles will be moving faster increasing the frequency of collisions and making the collisions harder
what are some sources of error when doing a temp experiment? how can you solve these issues?
using judgement which would result in inaccurate measurements being taken. instead use a colorimeter which will measure light to give a more accurate measurement.
what are catalysts?
substances that change the rate of a reaction without being used up.
how do catalyst work?
they lower the activation energy by providing an alternative pathway for the reaction
how does the concentration affect the rate of a reaction?
lower concentration causes less frequent collisions and slower rate of reaction
higher concentration causes more frequent collisions and a faster rate of reaction.
how does surface area affect the rate of a reaction?
the smaller the surface area the less frequent collisions are and the slower the reaction rate
the larger the surface area the more frequent collisions are and the higher the reaction rate
