rates of reaction Flashcards
how can the rate of a reaction be followed?
measure the amount of product formed over time eg the amount og gas given off every 30 seconds using a gas syringe
why are reactions faster at the start?
they have the maximum amount of starting material so the maximum number of collisions
how does a chemical reaction happen?
if the particles of each starting material collide with one another. However they also have to collide with a certain amount of energy, this is the activation energy.
how does surface area increase the rate of reaction?
by increasing the surface area there are more particles on the surface and available for reactions. this increases the chance of successful collisions therefore increasing the rate.
how do you increase the surface area?
by cutting the solid in smaller pieces
how does temperature increase the rate of reaction?
increasing the temperature causes the particles to have more kinetic energy increasing the rate of successful collisions, therefore increasing the rate.
how does concentration increase the rate of reaction?
increases the concentration increases the number of particles of the chemical in the same volume. This increases the chance of successful collisions and therefore the rate.
how does using a catalyst increase the rate of reaction?
it increases the rate of reaction but isn’t used up itself. each catalyst works for one reaction.
when do reactions finish?
when one or more of the starting materials is completely used up.
how do you calculate the rate from a graph?
change in x
how can you tell the reaction is finished from a graph?
the line goes flat
why is cotton wool in the neck of the flask?
to allow gas to escape but not liquid
why is a gas syringe more accurate?
it is more precise
why do catalysts have to be replaced?
they are affected by impurities and loses its activity over time.
the steeper the line..
the steeper the curve.
