rates of reactions Flashcards
what is the equation for the mean rate of reaction(product)
quantity of products formed /time taken
gas products
are measured in cm^3
graphs
- the steeper the graph the faster the reaction
- when there is a turning point the reaction is slowing down
- when the line is flat he reaction has stopped
what is the mean rate of reaction (reactants)
quantity of reactants used /time taken
slope graphs
the slope of the graph gives us an idea of the rate of reaction
how to draw a tangent
- draw a tangent
- draw a triangle
- find the x-axis and y-axis
- divide y/x
What is the collision theory?
chemical reactions can only take place when the reacting particles collide with each other. The collisions must have sufficient energy
what is the rate determined by?
The frequency of collisions
effect on concentration on rate -graph
beginning -initially rapid because we have a large number of reactants molecules
middle-over time the reaction slows down because the number of reactant molecules is running out
end-reaction stops because all of the reactant molecules have run out
what is the rates and concentrations relationship?
rate is proportional to the concentration
the higher concentration is:?
- quicker -you can see from the steepness
- gives more products-higher products line
Surface area
- particles in a solution can only react to the outside surface
- small sa means a lot of inside particles can’t be reached
- -the rate increase as we increase the sa of a solid reactant
SA: V
smaller blocks have a greater SA: V ratio
-they have more particles on the surface, so there are more collisions per seconds
how to find out the effects on SA
set up a conical flask put in the acid and solid put a bong in, connect with a tube into a basis full of water and cover that pipe with a measuring cylinder and measure the volume of gas
how to find the effect of a (more accurate)
set up a conical flask with the acid and the solid and use a gas string to measure the volume of gas
temperature effect; what is activation energy?
the minimum amount o energy the particles must have in order to react
what happens there not enough activation energy?
the particles cannot overcome the activation energy barrier
what happens if there’s enough activation energy?
enough energy to overcome the activation energy barrier
what is the relationship with temp and rate?
increasing the temperature would increase the rate of reaction -particles have more energy
rate f reaction is proportional to temperature
Catalyst?
increases the rate of a chemical reaction but are not used up during the reaction
how does a catalyst save money?
- catalyst allows us to carry out reactions quickly without needing to increase the temperature.This saves money
- because catalysts are not used up during a reaction , we can reuse it again and again
what does a catalyst have to do with activation energy?
a catalyst increases the rate by providing a different pathway for a reaction -that has a lower activation energy
when a catalyst lowers the activation energy what happens to the reaction?
-more particles successfully collide per second which increases the rate of reaction
why isn’t a catalyst written in the equation?
because catalyst are not actually involved n the reaction and are not a reactant
