Reactions Flashcards
what are the 3 factors that affect reactions?
temperature
concentration and pressure
surface area: volume ratio
what must happen for 2 particles to react
the particles must collide with each other and also have enough energy to start the reaction
what is the activation energy?
the minimum energy needed by a reactant particles for a reaction to happen
how do concentration and pressure affect the rate of reaction?
as conc and pressure increase the rate of reaction increases. this is because there will be more particles in the same volume which means that the frequency of successful collisions will increase (more collisions as there will be less free space)
how does temperature affect the rate of reaction?
the rate of reaction increases when the temperature increases because the particles will gain kinetic energy meaning that:
- the particles move faster
- more collisions
- more energy so a greater proportion of the collision will be successful
how does the surface area: volume ratio affect the rate of reaction
increases when the ratio increases as more particles of the reactant will be available, which will increase the frequency of successful collision
how do catalysts work
they provide an alternative reaction pathway that requires less energy
what are the 2 types of reactions?
endothermic and exothermic
what is an endothermic reaction?
where heat energy is taken in from the surroundings, decreasing the temperature
what is an exothermic reaction?
where heat energy is given out to the surroundings
give a reaction type that is always exothermic
displacement
give 3 reaction types that can be exothermic or endothermic
neutralisation, precipitation and dissolving
why do exothermic reactions give out energy?
energy is released when bonds are made
why do endothermic reactions take in energy?
energy is needed to break bonds
describe the reaction profile of exothermic reactions
reactants have more energy than products
negative energy change
