Mid Term Flashcards
Disappearance Rate
Reaction rate for a reactant since reactants are being consumed.
Rate of reaction (Reaction Rate) and units
Change of amount of reactant or product per unit time
M/t or mol/L*t
Appearance Rate
Reatction rate of a product since products are being created.
Relative Reaction Rate (used when?)
When we want to know the rate of reaction (reaction rate) of one reactant or product given another.
aA + bB –> cC + dD (Relative Reaction rate expression)
-1/a delta[A]/delta[t] = -1/b delta[B]/delta[t] = 1/c delta[C]/delta[t] = 1/d delta[D]/delta[t]
Factors that increase the rate of reaction (and how it relates to collision theory).
- Nature of reactants
- Concentrations
- Temperature
- Surface area
- Presence of catalyst
Why does surface area increase the rate of reaction?
Increasing the surface area gives the reactant more locations at which to react, thus increasing the reaction rate.
Rate Laws (def)
Mathematical expressions that describe the relationship between the rate of a reaction of a chemical reaction and the concentration of its reactants.
Rate Law Equation
rate = k[A]^m[B]^n
Chemical Kinetics
Study of how fast chemical reactions proceed from reactants to products.
Initial Rate of reaction
Instantaneous rate at the start of a chemical reaction
Rate Law
Mathamatical expression that describes the relationship between the reaction rate of a chemical reaction and the concentration of its reactant
Rate = k[A]^x[B]^y
Reaction Order
How concentration affects the reaction rate.
Zero Order Reaction
The concentration doesn’t affect the reaction rate.
Rate = k
1st Order
Concentration affects the reaction rate
Rate = k[A]^1
2nd Order
Concentration greatly affects the reaction rate.
Rate = [A]^2
What does tripling the concentration do the reaction rate in regards to zero, 1st, and second order reactions?
Zero - No affect 3^0 (concentration) = 1(rate)
1st - triples 3^1 (concentration) = 3 rate
2nd - increase by a factor nine. 3^2 (concentration) = 9 reaction rate.
K constant
Tells us how fast the reaction is going.
(the higher the k constant the faster the reaction)
Rate constant units based on order numbers (zero, first, and second). (Two units for each might be on the test)
Zero = M^1 t^-1 or M/t
1st = M^0 t^-1 or t^-1 or 1/t
2nd = M^-1 t^-1 or 1/M*t
Units for reaction rate and rate constants (based on the reaction order) formula
M^1-n t^-1
n = reaction order or overall reaction order
Evaluate experimental data to determine reaction orders, rate constants, and overall rate laws for given reactions. (steps and how to solve for k)
- Choose trial in which only one of the reactant changes.
- Find the changes in concentrations and initial rates of those trials.
- Set up concentration change to the x power = change in rate.
- Solve for x to find reaction order.
- Plug in the concentrations and rate from one trial into the update rate law to solve for k.
How to determine which trial to use when solving for rate constant? (Put in answer from professor)
Rate of reaction (Reaction Rate) unit
M/t
Determine the rate law (find what)?
Find reaction orders
Collision Theory
For particles to react they must collide together with sufficient energy.
Rate of reaction (depends on what)? (two things)
- Frequency of collisions
- Amount of energy the particles have
-more energy they can transfer during
collisions.
Integrated Rate Law Def
Second form of each rate law that relates the concentrations of reactants and time
Integrated Rate Law Equations (zero, 1st, 2nd order).
Zero: [A]t = [A]o - kt
1st: ln[A]t = ln[A]o - kt
2nd: 1/[A]t = 1/[A]o + kt
[A]t means concentration at some time.
Arrenius Equation
Mathematical expression that relates rate constant, activation energy and temperature together.
Can take multiple formats.
Ea Unit
J/mol or kJ/mol (depends on what they ask)
