Defenitions rates, equilibrium and ph Flashcards
Rate of reaction
Change in concentration of reactant it product per unit time
Initial rate of reaction
Change in concentration of a reactant or product per unit time at the start of a reaction, t=0
What is order?
Order with respect to reactants if the power to which the concentration of the reactant is raised in the rate equation
Overall order
Sum of all individual orders
Rate constant, k
Constant that links the rate of reaction with the concentrations of the reactants raider to powers of their orders in the rate equation
Half life
The time taken for the concentration of the reactant to reduce by half
Reaction mechanism
A series of steps that make up overall reaction
Rate determining step
Slowest step in the reaction mechanism of a multi step reaction
Intermediate
A species formed in one step of a multi-step reaction that is used in a subsequent step and is not seen as either a reactant or a product if the overall equation
Dynamic equilibrium
Exists in a closed system, where the rate if the forward reaction is equal to the rate of the reverse reaction
Homogenous equilibrium p
Equilibrium in which all species are making up the reactants and products are in the same physical state
Heterogenous equilibrium
An equilibrium in which species making up reactants and products are in different physical states
Concentration
Mol/vol
Kc
Equilibrium constant (Products)^balancing numbers/(reactants)^balancing numbers
Brønsted-Lowry acid
A proton, H+ donor
Brønsted-Lowry base
A proton acceptor
Alkali
A base that dissolves in water forming OH- ions
Neutralisation
Chemical reaction in which acid and base react to produce a salt and water
Acid base pair
Two species that transform into each other by gain or loss of a proton
pH
-log(H+
H+
10^-pH
Strong acid
Acid that completely dissociates in solution
Weak acid
Acid that partially dissociates in solution
COD dissociation constant
Extent of acid dissociation
Ka = (H+)(A-)/(HA)
Ka
10-pKa
pKa
-log(Ka
Strong acid calculation
(H+)=(HA)
Weak acid calculation
H+ = sq root Ka x (HA)
Ionic product of water
Kw= (H+)(OH-)
Controls balance between H and OH in all aqueous solutions
Value of Kw at 25 degrees
1x10-14 mol2dm-6
pH of strong base
(OH)=(base)
H+ = Kw/OH-
Buffer solution
Mixture that minimises pH changes in addition if small amounts of acid or base
Buffer calculations
H+ = Ka x HA/A-
Equivalence point
Point in a titration at which the volume of one solution has reacted exactly with the volume of the second solution
End point
Point in a titration at which there are equal concentrations of weak acid and conjugate base forms of the indicator, colour at endpoint midway between acid and base colours
Standard enthalpy change of neutralisation
Energy change that accompanies the neutralisation of an aqueous acid by an aqueous base to form one mole of water under standard conditions
