Factors that Affect Reaction Rates Flashcards
Temperature General Description
As temperature increases, reaction rate increases
Concentration of Reactants General Description
As concentration of reactants increases, reaction rate increases
Surface Area General Description
As surface area increases, reaction rate increases
Catalyst General Description
Presence of a catalyst increases reaction rate
Homogeneous catalyst
- Same physical state as the reactants
- Usually a gas or liquid
Heterogeneous catalyst
- Different physical state from the reactants
- Usually a solid
The Nature of the Reactants General Description
Chemical compounds vary considerably in their chemical reactions
Temperature - point A
As temp increases, more entities in the sample will have sufficient Ea to break bonds of reactants and form an activated complex
Temperature - point B
As temp increases, the rate of reaction increases therefore there will be an increase in the # of successful collisions between reactants
Concentration=
moles/volume
Concentration Point A
More particles in a particular space means more chances of colliding
Concentration Point B
Increasing pressure of a gas has the same effect as increasing concentration
Surface Area Point A
only atoms, ions or molecules at the surface of a solid can collide with other entities
Surface Area Point B
As surface area increases the probability of effective collisions increases aswell
What do catalysts not affect?
- # of collisions
- Kinetic energy
What do catalysts do?
- Provide an alternative pathway for the reaction that has a lower Ea
- Increase reaction rate but do not get used up in reaction
What does a positive catalyst do?
Lowers Ea
What does a negative catalyst (inhibitor) do?
Increases Ea
Why do gases react faster than liquids and solids?
Because they take less energy to overcome IMF’s
What state reacts the fastest?
- Aqueous ions
- In aqueous solution, the ions of each compound are dissociated
Bond Type
Less energy is required to break single bonds than double or triple bonds
Bond Strength
Weaker bonds are broken at a faster rate
Bond Number
Fewer bonds proceed faster
What is another factor that affects Ea
Bond type, strength and number
Size and shape of the molecule or ion
- Complicated structures are less reactive
- More bonds must be broken and they are less likely to collide in the correct orientation