F325 Rates, equilibrium and pH

?
  • Created by: Madeleine
  • Created on: 29-05-13 22:14
Define rate of reaction
The change in concentration of a product or reactant per unit time
1 of 33
Define order
Order, with respect to a reactant, is the power to which the reactants concentration is raised in the rate equation
2 of 33
Define rate constant
The constant which links the rate of reaction with the concentrations of the reactants raised to the powers of their orders in the rate equation
3 of 33
Define half-life
The time taken for the concentration of the reactant to reduce by half
4 of 33
Explain the rate-determining step
The slowest step in the reaction mechanism of a multi-step reaction
5 of 33
If a concentration-time graph is; a. a straight diagonal line, b. a curve with a constant half-life and c. a curve what is the order of the reactant?
a. Zero order b. First order and c. Second order
6 of 33
The half-life of a first-order reaction is?
Independent of the concentration
7 of 33
If a rate-time graph is; a. a straight lin, b. a diagonal straight line c. a curve what is the order of the reactant?
a. Zero order b. First order c. Second order
8 of 33
If a reactant's order is zero how does its concentration affect the rate?
It doesn't.
9 of 33
If a reacts order is first how does its concentration affect the rate?
The rate is directly proportional to the concentration, i.e. if the concentration doubles then so does the rate
10 of 33
If a reacts order is second how does its concentration affect the rate?
The rate is proportional to the concentration squared, i.e. if the concentration doubles the rate quadruples
11 of 33
What is the rate equation for the reactants A and B with order m and n respectively?
rate=k[A]^m{B]^n
12 of 33
How does a change in temperature effect the rate constant (and hence rate) of a reaction?
A temperature increase means the molecules have more energy which means there are more frequent collisions and more of the collisions exceed the activation energy. The rate constant is larger with temperature increase.
13 of 33
What is the equation for the equilibrium constant for the equation; aA + bB > cC + dD
K(subscript c) = [C]^c[D]^d/[A]^a[B]^b
14 of 33
How does a change in temperature affect the equilibrium constant of an endothermic reaction?
As temperature increases, the equilibrium constant decreases (equilibrium yield of products increase and therefore the equilibrium yield of reactants decreases)
15 of 33
How does a change in temperature affect the equilibrium constant of an exothermic reaction?
As temperature increase, the equilibrium constant decreases (equilibrium yield of products decrease therefore equilibrium yield of reactants increases)
16 of 33
How is the equilibrium constant affected by changes in concentration, pressure, or a catalyst being present in the reaction?
It is unaffected.
17 of 33
Describe an acid
A species which can donate a proton
18 of 33
Describe a base
A species which can accept a proton
19 of 33
Define conjugate acid-base pairs
A pair of two species which transform into each other by gaining or losing a proton
20 of 33
What is the difference between a strong and a weak acid?
Strong acids dissociate completely in aqueous solution whereas a weak acid only partially dissociates
21 of 33
What is H^+ role in reactions of acids with metals, carbonates, bases and alkalis?
The proton is the active ingredient in acids and is resposible for typical acid-base reactions
22 of 33
For the reaction: HA(aq) > H^+ (aq) + A^-(aq) deduce the acid dissociation constant
K(subscript a) = [H^+(aq)][A^-(aq)]/[HA(aq)]
23 of 33
How do you find pK(subscript a)??
Using pK(subscript a)=-log(base=10)K(subscript a)
24 of 33
Define pH
pH= -log[H^+] of [H^+] = 10^-pH
25 of 33
Define the ionic product of water
K(subscript w)=[H^+(aq)][OH^-(aq)]
26 of 33
Calculating pH for a; a. strong acid, b. weak acid, c. strong base you need to use:
a. [H^+(aq)]=[HA(aq)] b.[H^+]=[A^-] so K(subscript a)=[H^+]^2/([HA]-[H^+]) c. Using the ionic product of water
27 of 33
Describe a buffer solution
A system which minimises pH changes on the addition of small amounts of an acid or a base
28 of 33
What is a buffer solution made from?
A weak acid and its salt
29 of 33
What is the role of the conjugate acid-base pair in a buffer solution?
The weak acid HA removes added alkali, as the small concentration of H^+ reacts with the OH^- ions, the HA dissociates in order to restore the H^+ ions. The conjugate base A^- removes added acid by reacting with the added H^+ ions.
30 of 33
What is the role of the carbonic acid-hydrogencarbonate buffer?
This buffer controls the pH of blood using the equilibrium H2CO3 > H^+ + HCO3^-. When acid is added the equilibrium shifts to the left and when an alkali is added the equilibrium shifts to the right
31 of 33
How is an indicator chosen for a titration?
The end point of the titration must be within the range of the indicator.
32 of 33
Define enthalpy change of neutralisation
The energy change which accompanies the neutralisation of an aqueous acid by an aqueous base to form one mole of water under standard conditions.
33 of 33

Other cards in this set

Card 2

Front

Define order

Back

Order, with respect to a reactant, is the power to which the reactants concentration is raised in the rate equation

Card 3

Front

Define rate constant

Back

Preview of the front of card 3

Card 4

Front

Define half-life

Back

Preview of the front of card 4

Card 5

Front

Explain the rate-determining step

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all Equilibria resources »