C8- Rates And Equilibrium Flashcards
Two ways to work out the rate of a chemical reaction
Find out how quickly:
. The reactants are used as they make products
. The products of the reaction are made
Three rate of reaction methods(practicals)
Measuring the decreasing mass of a reaction mixture
Measuring the increasing volume of gas given off
Measuring the decreasing light passing through a solution
Factors which affect the rate of chemical reactions
Temperature
Surface area (of solids)
Concentration
Pressure
Presence of a catalyst
What is activation energy?
The minimum amount of energy that particles must have before they can react
What is collision theory?
The reacting particles do not only have to bump into each other, but also need to collide with enough energy to cause a reaction to take place.
How to make reactions more likely to happen?
Increase the frequency of reacting particles colliding with each other
Increase the energy they have when they collide
Surface area and reaction rate
In smaller lumps or in powder each tiny piece of solid is surrounded by solution. This means that many more particles are able to react than if it was just one large solid. This means that reactions can take place much more quickly is solids are broken up and the surface area is increased.
Temperature and reaction rate
When a substance is heated energy js transferred to its particles which means that they move around faster which means that there are more successful collisions . Additionally the particles have more energy so the reaction rate increases.
Concentration and reaction rate
Increasing the concentration of reactants in a solution increases the rate of reaction because there are more particles of the reactants moving around in the same volume of solution. The more ‘crowded together’ the reactant particles are, the more likely it is that they will collide. So the increased frequency of collisions results in a faster reaction.
Pressure and reaction rate
Increased pressure squashes the gas particles more closely together. There are more
particles of gas in a given space. This increases the chance that they will
collide and react. So increasing the pressure produces more frequent
collisions, which will increase the rate of the reaction.
