Year 13 Rate, Equilibrium and pH Key Definitions OCR Chemistry A

?
Rate of reaction
The change in the concentration of a reactant or product per unit time
1 of 32
The Order
with respect to a reactant is the power to which the concentration of the reactant is raised in the rate equation
2 of 32
Rate constant,k
The constant that links the rate of reaction with the concentrations of the reactants raised to the powers of their orders in the rate equation
3 of 32
Rate equation
For a reaction A+B->C is given by rate=k[a]^m[b]^n where m and n are orders
4 of 32
The overall order
Of reaction is the sum of the individual orders, m+n
5 of 32
Zero Order
The rate is unaffected by changing the concentration of A
6 of 32
First Order
The rate is directly proportional to the concentration. Eg. if the concentration doubles, the rate doubles
7 of 32
Second Order
The change in rate is equal to the change in concentration squared. Eg. if concentration x2 then rate increases by 4x (2^2)
8 of 32
Half Life
of a reactant is the time taken for the concentration of the reactant to reduce by half
9 of 32
Reaction Mechanism
A series of steps that together make up the overall reaction
10 of 32
Rate-determining step
The slowest step in the reaction mechanism of a multi-step reaction
11 of 32
Intermediate
Species formed in one step of a multi-step reaction that is used up in a subsequent step, and is not seen as either a reactant or product of the overall equation
12 of 32
Equilibrium Law
States that for the equilibrium aA+bB<->cC+dD Kc=[C]^c[D]^d/[A]^a[B]^b
13 of 32
Homogenous Equilibrium
An equilibrium in which all the species making up the reactants and products are in the same physical state
14 of 32
Heterogenous Equilibrium
An equilibrium in which species making up the reactants and products are in different physical states
15 of 32
Mole Fraction
A measure of how much of a given substance is present in a reaction mixture. No. of moles of substance A/total no. of moles of all substances
16 of 32
Partial Pressure
The pressure an individual gaseous substance would exert if it occupied a whole reaction vessel on its own. Mole fraction x total pressure
17 of 32
Bronsted-Lowry Acid
A proton ,H+, donor
18 of 32
Bronsted-Lowry Base
A proton, H+, acceptor
19 of 32
Alkali
A base that dissolves in water forming OH- (aq) ions
20 of 32
Neutralisation
Is a chemical reaction in which an acid and a base react together to produce a salt and water
21 of 32
A strong acid
An acid that completely dissociates in solution
22 of 32
A weak acid
An acid that partially dissociates in solution
23 of 32
Acid dissociation constant, Ka, of an acid HA
Ka=[H+][A-]/[HA]
24 of 32
pKa
-log10(Ka)
25 of 32
Ka
10^-pKa
26 of 32
pH
-log[H+]
27 of 32
[H+]
10^-pH
28 of 32
Ionic Product of water, Kw
Kw=[H+][OH-]. At 25 degrees, Kw=1.00 x 10^-14 mol^2dm^-6
29 of 32
Buffer solution (weak acid,HA, and its conjugate base,A-)
A mixture that minimises pH changes on the addition of small amounts of acid or base. Made from a weak acid and a salt of the weak acid or a weak acid and strong alkali which forms a solution of a salt and excess of weak acid.
30 of 32
Equivalence Point
The point in a titration at which the volume of one solution has reacted exactly with the volume of a second solution. This matches the stoichiometry of the reaction taking place. It is at the half way point of the vertical section of the graph
31 of 32
End Point
The point in a titration at which there are equal concentrations of the weak acid and conjugate base forms of the indicator. The colour at the end point is midway between the colours of the acid and the conjugate base forms
32 of 32

Other cards in this set

Card 2

Front

with respect to a reactant is the power to which the concentration of the reactant is raised in the rate equation

Back

The Order

Card 3

Front

The constant that links the rate of reaction with the concentrations of the reactants raised to the powers of their orders in the rate equation

Back

Preview of the back of card 3

Card 4

Front

For a reaction A+B->C is given by rate=k[a]^m[b]^n where m and n are orders

Back

Preview of the back of card 4

Card 5

Front

Of reaction is the sum of the individual orders, m+n

Back

Preview of the back of card 5
View more cards

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all Rates resources »