Kinetics Flashcards
what does collision theory state?
for a chemical reaction to take place, the particles need to collide with each other in the correct orientation and with enough energy
what is collision frequency
number of collisions per unit time
what happens when collision frequency increases
number of particles with energy greater than the Ea increases - causing an increase in the rate of reaction
what is activation energy
minimum amount of energy required for a reaction to take place
which has larger Ea : endothermic reactions or exothermic reactions. And why?
Ea is larger in endothermic reactions because the reactants are lower in energy than the products
what is a catalyst?
a substance that increases the rate of reaction without being used up, by providing the particles with an alternative pathway with a lower activation energy
rate of reaction formula
change in amount of reactants/products / time
mol dm-3 / s
units for rate of reaction
mol dm-3 s-1
what is a maxwell boltzmann distribution curve
a graph that shows the distribution of energies at certain temperature
what happens to the MB curve when temp is increased? And why?
when temperature ↑↑, Ek ↑↑, so more frequent collisions, so more frequent successful collisions.
This means that more particles possess the Ea.
MB curve flattens and peak shifts to the right when temp ↑↑
what happens to the MB curve when you remove half the molecules?
Curve peak halves in height and theres less area after the Ea mark.
Ea and Emp stay the same
what happens to the MB curve when a catalyst is added?
stays the same except the Ea shifts to the LEFT
what happens to the MB curve when volume changes
nothing changes
what happens to the MB curve when temperature is reduced?
Emp shifts to the left, Ea shifts to the right, steeper curve, less area past the Ea mark
what does increasing temperature do to rate of reaction?
↑↑ temp
↑↑ in Ek of particles
↑↑ number of collisions
↑↑ number of successful collisions
↑↑ the rate of reaction
