Kinetics Flashcards
What are the five methods for measuring rates of reaction
Change in gas volume Change in gas pressure Change in mass Change in colour Sampling
How do you measure initial rates of reaction using a graph?
Draw a line from a point on the graph to the y axis and label it MP
Draw a line from M to where the reaction starts on the y axis and label it MN
MN/MP = rate
What factors affect the rate of a reaction?
Temperature concentration/pressure Surface area Catalyst Light(some cases)
What is collision theory?
For a chemical reaction to take place, reacting molecules must collide. However, only a small fraction of collisions leads to a reaction because the molecules must collide with sufficient energy and be in the correct orientation. Minimum energy needed is called activation energy.
Why does concentration/ pressure/ surface area effect reaction rates?
More molecules in same volume
Greater chance of molecules colliding
Greater chance of successful collisions with activation energy
How does temperature effect reaction rates?
Molecules have more kinetic energy
Moving fast so collide more often
More energy than activation energy
How do catalysts effect reaction rate
Provides an alternative route with lower activation energy
Greater proportion of molecules have sufficient energy
Increases rate of forward and backward reactions
What is a heterogeneous catalyst and what is an example of one?
Different phase to reactants
Iron Haber process-ammonia
Nickel- margarine
Vanadium V oxide- sulphuric acid
What is a homogeneous catalyst and give an example?
Same phase as reactants
Concentrated sulphuric acid- ester from a carboxylic acid and alcohol
Why are catalysts important in industry?
Less energy required
Saves energy costs
Less fossil fuels need to be used
Less CO2 emissions
Difference between equilibrium and reaction rate?
Equilibrium- balance between reactants and products and how balance is affected by change in conditions
Kinetic- how fast and mechanism
Equation for rate of a reaction
Rate= change in conc/ time
