3.1.5 Kinetics Flashcards
What does the study of kinetics enable chemists to do
How to determine how a change in conditions affects the speed of a chemical reaction
Define rate of reaction
Change in concentration in a given period of time
What allows reactions to take place between particles
If they collide and have enough energy to break bonds - successful collisions
Why do most collisions between molecules not lead to a reaction
They do not have sufficient energy or they do not have the right orientatiom
What is activation energy
The minimum energy needed to start a reaction
Describe exothermic reactions
They give out heat
This means that the products have less energy (enthalpy) than the reactants
Reaction profile main parts:
Top of curve: represents transition state/activated complex
This means bonds are being both broken and made
Define endothermic reactions:
Products have more energy than the reactanrs
Label the axes of a maxwell-Boltzmann distribution diagram
X: energy
Y: number of molecules
Why do maxwell-Boltzmann graphs starts at the origin
Because zero molecules have zero enery
What does the area under a maxwell-Boltzmann curve represent
The number of molecukes
Define activation energy
The minimum energy required to start a reaction
What do higher temperatures do to a maxwell-Boltzmann curve
Peak is lower and shifted right
Number of particles with high energy increases, but total area under curve is constant
Many more molecules with with an energy greater than the activation energy
Why does a rise of 10 degrees Celsius double the rate of reaction
Twice as many particles possess the activation energy
What effect does increasing the concentration of a solution have on the rate of reaction
More particles in a given volume = more successful collisions, reaction rate increases
But as reaction proceeds, reactants are used up, so rate decreases as reaction proceeds
Doubled concentration = doubled rate of reaction
