7 Chemical Reactions Flashcards
(32 cards)
When does a reaction take place
when particles collide with a certain amount of energy
What does a rate of reaction depend on (2)
Reacting particles must have the correct geometry
Particles must collide with sufficient energy
Why does the rate of reaction slow down over time? (2)
As the reaction progresses, the concentration of reactants decreases
This reduces the frequency of collisions, slowing down the reaction
How would a graph of a reaction look like?
u know it bro
What are the two ways the rate of reaction can be measured (2)
how quickly a reactant is being used up
how quickly products are being formed
Eqt for average rate of reaction
change in quantity/ change in time
Define activation energy
minimum amount of energy required for a chemical reaction to take place
What happens when particles collide with energy lower than the activation energy
successful collision will not occur and the particles will not react
Why do reactant particles have to meet the activation energy (2)
To break old bonds of the reactant particles, in order to form new bonds of the products
Breaking bonds is an endothermic process and so requires energy to be put into the system
Define collision geometry
position and co-ordination of particles as they collide
What are the four factors that can speed up a chemical reaction (4)
Concentration
Temperature
Particle size/surface area
Use of catalyst
Why does increasing concentration increase rate of reaction
there are more particles that can collide together and react
Correlation between concentration and rate of reaction
higher the concentration, higher the rate of reaction
Temperature is a measure of what?
measure of how much kinetic energy reactant particles have
Relationship between temperature and rate of reaction
higher the temperature, the higher the rate of reaction
Why do particles at higher temperature react at a faster rate (2)
Higher temperature particles have more kinetic energy and so move about more
Due to the particles moving, there is a greater chance of the particles colliding and so reaction happens faster
Relationship between particle size and surface area
smaller the particle size, the greater the surface area
Why are small particle sizes potentially dangerous in industry (2)
Incredibly fine particles have large surface area
If they catch fire, the rate of combustion will be very fast, leading to dust explosions
Dangers in coal mines involving concentration and temperature (3)
At high concentrations, methane (flammable gas) can form an explosive mixture with air
This is because as there are more reactants colliding, there is more heat energy, this leads to an increase in temperature, leading to higher kinetic energy. This means particles have sufficient energy to collide
This further increases the temperature of the mixture until, eventually, the reaction mixture explodes.
Define catalyst
substance that can be used to increase the rate of reaction without being used up and can be recovered unchanged at the end of a reaction
catalysts are said to be “______ ______”
reaction specific
What does a catalyst do to the activation energy
lowers activation energy
Define oxidation
gain of electrons
Define reduction
loss of electrons
