First Test Flashcards
What observation supports the KMT postulate that states: particle motion is random
Pressure is uniform in all directions
What observation supports the KMT postulate that states: particles are very far apart
IGL only works at low gas densities
What observations support the KMT postulate that states: gas particles do not interact
IGL is independent of particle type and Dalton’s Law of Partial Pressures
Postulates of the KMT?
1) gas particles are in constant random motion
2) pressure is due to particle collisions with walls of container
3) gas particles are very far apart
4) gas particles do not exert forces on each other (due to being far apart)
What two laws does KMT come from?
IGL and Dalton’s LoPP
When is the IGL not valid?
At high densities and pressures
For a fixed T, the speed of gas molecules depends on…
The molecular mass of the gas
For a fixed T, total KE for one mole is….
The same for all gases
What two factors is P dependent on?
1) frequency of collisions
2) how hard the collisions are
Why does increasing density increase pressure?
Because it increases the frequency of the particles hitting the walls of the container
Why does increasing T increase P?
Increasing T increases the speed of the molecules and thus the frequency as well
Negative deviations from IGL
As density (n/V) increases, observed P is less than P predicted by IGL (nRT/V)
Negative deviations from the IGL occur because of…
Intermolecular attractions that decelerate particles by attracting particles to other particles
Positive deviations of the IGL are caused by…
Intermolecular repulsions that accelerate the particles
Negative deviations do what to P
Lower Pressure relative to IGL predictions
Positive deviations do what to P
Increase pressure relative to IGL predictions
What is mean free path
The average distance a particle will travel before hitting another particle
The rate of a chemical reaction can be no greater than….
The rate at which the particles run into each other
Reaction rate is proportional to…
reactant concentration
If rate doubles when concentration doubles?
n=1
If rate quadruples when concentration is doubled
n=2
First order
Rate=k[A]
Second order
Rate=k[A]^2
Or
Rate=k[A][B]
Why does increasing temp, increase the rate of the reaction
Because according to KMT, increase in T is equal to an increase in kinetic energy. Therefore, as T increases, the fraction of molecules with sufficient energy to surmount the reaction activation barrier increases.
Activation energies are much, much ____ than bond energies. Why?
Lower.
Because bonds are broken and formed at the exact same instant in reactions
The sequence of elementary processes leading to the overall reaction is referred to as the…
Reaction mechanism
The slowest step in a multi-step process is called the….
Rate-determining or rate-limiting step
Is made then consumed in a rxn
Intermediate
Is consumed then regenerated in a rxn
Catalyst
IF reaction occurs in a single collision, order of the reaction is determined by the stoichiometry. THEREFORE:
IF the rate law differs from the stoichiometry, the reaction does not occur in a single collision.
In reaction mechanisms, the overall rate of the reaction is determined by….
The rate determining (slow) step
The collision rate does not equal…
The reaction rate
What else is required for a reaction to occur BESIDES a collision?
Sufficient energy
Appropriate orientation
Random factors (phase of molecular vibrations)
Even for exothermic reactions ____ is still required
Activation energy
Boyle’s Law
Pressure and volume are inversely related, as P goes up, V goes down, at fixed T and n
Charles law
Volume and temperature are directly related, as volume increases so does temperature, at fixed P and n
Avogadro’s Law
Volume and number of moles are directly related, as V increases so does n, at fixed T and P
Dalton’s law of partial pressures
The total pressure exerted in a mixture of gases is equal to the sum of the partial pressures of the individual gases.
