Chemistry Flashcards
(20 cards)
What is rate of reaction?
the speed at which a reaction takes place.
What are three main methods to measure the rate of reaction:
Change in mass
Volume of gas formed
Formation of a precipitate
List some factors that can affect the rate of a chemical
reaction.
Temperature Surface area
Pressure If catalyst is present
What is collusion theory
For particles to react they have to collide with each other they have to have activation energy
How does temperature affect rate reaction?
When the temperature is increased, the particles gain more energy meaning they move faster overall meaning they collide more often and they exceed their activation enegry
How does pressure affect the rate reaction?
If pressure is incresed this means there is more particles per unit of volume which makes the collisions more often overall leading to the rate of reaction being incresed
How does surface area affect rate reaction?
If the surface area of a reactant is increased: more particles are exposed to the other reactant. there is a greater chance of particles colliding, which leads to more successful collisions per second. the rate of reaction increases.
How does a catalyst affect the rate of reaction?
It lowers the activation energy creating a alternate reaction pathway reaching a higher portion of successful collisions
What is a catalyst?
a substance which speed of reaction without being used in the reaction itself
What happens to the rate of reaction of the temperature decreases?
The temperature decreases the rate of reaction will generally slow down because lower temperatures means they have less kinetic energy meaning fewer collisions
What is activation enegry?
The activation energy is the minimum energy reacting particles must have when they collide for the reaction to take place
Describe how surface area of a solid can be increased.
This is done by cutting the substance into small pieces, or by grinding it into a powder. Making the surface area larger
Describe how changing pressure of gaseous reactants affects the rate of reaction.
If the pressure of gaseous reactants is increased, there are more reactant particles for a given volume. There will be more collisions and so the reaction rate is increased
Calculate the surface area to volume ratio.
Divide the surface area by the volume
How does changing the concentration affect the rate of reaction?
If the concentration of reactants is increased, there are more reactant particles moving together. There will be more collisions and so the reaction rate is increased.
What Mean rate of reaction?
Quantity of reactants used/ Time taken
What is the control variable?
Controlled variable – a variable that is kept the same during a scientific experiment.
What is ment by independent variable?
Independent variable – the variable that is altered during a scientific experiment
What is ment by dependent variable?
the variable being tested or measured during a scientific experiment.
