Kinetics Flashcards
(17 cards)
what are the factors affecting the rate of reaction
- temperature
- surface area (of solids)
- concentration (of solutions)
- pressure (of gases)
- catalysts
how does surface area affect the rate of reaction
Increasing surface area increases rate because more particles are exposed at the surface area and there is a higher frequency of successful collisions
how does concentration affect the rate of reaction
Increasing concentration increases rate because there are more particles in a given volume and there is a higher frequency of successful collisions
how does pressure affect the rate of reaction
Increasing pressure increases rate becaure there are more particles in a given volume and there is a higher frequency of successful collisions
how does temperature affect the rate of reaction
(has the biggest affect out of all the factors)
Increasing temperature increases rate because:
1. particles have more enegy and move more quickly resulting in a higher frequency of collisions
2. higher proportion of particles at or above the activation energy
3. collide more frequently and energetically
how does a catalyst affect the rate of reaction
Adding a catalyst increases rate because they offer an alternative pathway for the reaction with a lower activation energy
in the Maxwell-Boltzmann Distribution, why does the graph start at the origin
graph starts at the origin as no particles have 0 energy
in the Maxwell-Boltzmann Distribution, what does the area under the curve represent
total number of particles
on the Maxwell-Boltzmann Distribution graph, where would you find the most probable energy and the mean energy
most probable energy = peak/highest point of graph
mean energy = a little off to the right of the peak
in the Maxwell-Boltzmann Distribution, why does the graph never touch the x axis
never touches the x axis as there is no maximum energy
in the Maxwell-Boltzmann Distribution, what does the area under the end of the graph represent
proportion of particles at or above the Activation Energy
what happens to the Maxwell-Boltzmann Distribution graph when temperature is increased
- area under curve is the same number of particles
- proportion of particles at or above Ea increases
- a wider curve is produced finishing at a higher proportion of particles
what happens to the Maxwell-Boltzmann Distribution graph when a catalyst is added
- line is drawn at a lower Ea and so a higher proportion of particles are at or above the Ea
- area under the curve is the same number of particles
what are the 3 stages that occur on a graph with volume of gas plotted against time
- HIGH RATE - high concentration of reactants, high frequency of successful collisions
- RATE DECREASING - concentration of reactants is decreasing, therefore frequency of successful collisions is also decreasing
- REACTION STOPPED - rate is at zero, one of the reactants is limiting and has been used up
how would increasing temperature affect a rates of reaction graph
increases the rate but does not alter the final volume of gas
how would changing surface area affect a rates of reaction graph
- if the same volume of chips are present, however they are smaller/powdered, this will increase the rate but not alter the final volume of gas
- if the volume is doubled and the chips are smaller/powdered, this will increase the rate and double the volume of gas will be produced
how would increasing concentration affect a rates of reaction graph
a higher rate would occur and a greater final volume
e.g from 1 mol/dm3 to 2 mol/dm3
this would double the final volume of gas
