Topic 16 - Kinetics 2 Flashcards
Two ways the rate determining step can be found?
Look for the slowest step in a reaction.
Look for the step that contains both species in the rate equations as reactants.
What does a zero order reaction for concentration against time look like?
Straight line with a negative gradient
What is the rate determining step?
The slowest step in a reaction
What pathway do tertiary halogenoalkanes undergo in nucleophilic substitution?
SN1 pathway
What pathway do primary halogenoalkanes undergo in nucleophilic substitution?
SN2 pathway
How many steps are involved in a SN2 mechanism and how many molecules are required?
1 step
2 molecules required
How many steps are involved in a SN1 mechanism and how many molecules are required?
2 steps
1 molecule required
What is the transition state in the SN2 pathway?
Where both carbon halogen bond and carbon hydroxyl bond are attached at the same time.
Why can’t tertiary halogenoalkanes react in the SN2 pathway?
Steric Hinderance - OH group is blocked by 3 carbon groups.
What happens to an acidic mixture when sodium hydrogencarbonate is added?
Stops reaction
By neutralising acid
What is a heterogeneous catalyst?
A catalyst that is in a different physical state to reactants.
What is a homogeneous catalyst?
A catalyst that is in the same physical state to reactants.
What is autocatalysis?
Where a product of a reaction also functions as a catalyst.
What is the continuous method when determining the order of a reaction?
Taking a sample of mixture and half life is determined.
What is the initial rates method when determining the order of a reaction?
Measure initial rate, plot a rate against concentration graph.
Use shape to determine what order
What is meant by activation energy?
The minimum energy required for a reaction to occur.
Tungsten wire is a catalyst of the haber process.
Describe the stages in the catalytic decomposition of ammonia by tungsten.
Absorption of ammonia onto catalyst surface
Breaking of bonds in ammonia
Desorption of nitrogen and ammonia from surface of catalyst
In a concentration- time graph that is zero order. What can be said about the rate of reaction and concentration of the reactant?
The rate of reaction is independent of the concentration of whatever reactant.
Explain the purpose of starch in the iodine clock experiment when its neither present in the rate equation nor in the reaction equation.
Acts as an indicator and reacts with iodine.
Time how long it takes for the formation of blue-black complex to form and use this to calculate rate of reaction.
