KA5- Equilibrium Flashcards
What is the definition of equilibrium?
when the composition of the reactants and roducts remains constant indefanitly
What does K represent?
indicates the position of equilibrium
no units
what is not included in equilibrium constant calculations?
concentrations of pure solids and pure liquids are constant so are not included
What does the numerical value of equilibrium depend on?
endo and exo
the reaction temperature being changed
* for endothermic reactions a rise in temperature increases the K value (yield of product is increased)
* for exothermic reactions a rise in temperature decreases the K value (yield of product is decreased
Does the presence of a catalyst affect K?
No
What can also be used in place of H+ ions?
Hydrodium ions (H30+)
Water can act as a ____ or a ____
acid or a base (it is said to be amphoteric)
What is represented through Kw
the dissosiation constant for the ionisation of water is known as the ionic product and is represented as by Kw
What is Kw as 25 celsius
1 x 10^-14
pH= -log(10)[H3O+] to…
[H3O+]+10^-pH
In water and aqueous solutions with the pH of 7 what are the concentrations of H3O+ and OH-
both 10^-7 mol l^-1 at 25 degrees
What equation do you use if the concentrations of OH or H3O are known?
Kw or pH + pOH=14
What are the Brønsted-Lowry definitions of acids and bases?
acid- proton donator
base- proton acceptor
For every acid there is a ____, formed by the ____ of a proton.
conjugate base, loss
For every base there is a ____, formed by the ____ of a proton
conjugate acid, gain
Stong acids and ____ bases are ____ ____ into ions in a aqueous solution
strong, completely dissociated
Weak bases and ____ acids are ____ ____ into ions in a aqueous solution.
weak, only partially dissociated
Examples of strong acids are…
Hydrocholoric acid (HCl), Sulfuric acid and Nitric acid
Examples of weak acids are…
Ethanoic acid, carbonic acid and sulfurous acid
Strong bases are…
solutions of metal hydroxides
Examples of weak bases are…
ammonia and amines
What is Ka?
the acid dissociation constant
pKa=-log(10)Ka
To work out the approximate pH of a weak acid you use,
pH=1/2pKa-1/2log(10)c
(c being the concentration)
A ____ salt of a strong acid and a strong base dissolves in ____ to produce a ____ solution
soluble, water, neutral
A soluble salt of a weak acid and a strong base dissolves in water t produce what?
An alkaline solution
A soluble salt of a storng acid anf a weak base dissolves in water to produce what?
An acidic solution
The name of the salt produced depends on what?
the parent acid and base
Using the appropriate equilibria, the changes in ____ of hydronium and hydroxide ions of ____ solutions can be explained
concentations
salt
What is a buffer solution?
is a solution in which the pH remains approx. constant when small amounts of acid, base or water are added
An acid buffer consists of a solution of what?
weak acid and one of its salts made from a strong base
In an acidic buffer solution the ____ acid provides ____ ions when these ions are removed by the addition of a small amount of ____. the salt of the weak acid provide the ____ ____ which can absorb excess ____ ions produced by the addition of a small amount of acid.
weak
hydrogen
base
conjugate bases
hydrogen
A basic buffer consists of what?
a weak base and one of its salts
in a basic buffer solution the … base removes … … ions and the … … provided by the salt supplies … ions when these are removed.
weak
excess hydrogen
conjugate acid
hydrogen
What equation is used to find the pH of an acid buffer solution?
pH=pKa- log(10) {[acid/[base]}
What are indicators?
weak acids
What is K(In)?
the acid indicator dissociation constant. it has the following expression;
Kin=[H3O+][In-]/ [HIn]
In ____ solution the ____ of an acid idicator is ____ from that of its ____ ____.
aqueous, different, conjugate base
The colour of the indicator is determined by what?
The ratio of [HIn] to [In-]
The theorectical point at which colour change occurs is when?
When hydromium ion concentation ([H3O+]) = K(In-)
the colour change is assumed to be distinguishable when?
when [HIn] and [In-] differ by a factor of 10
What is the expression used to determine the pH range using a indicator?
pH=pK(In) +/- 1
