acids and bases Flashcards
1
Q
define a bronsted lowry acid
A
- a proton donor
2
Q
define a bronsted lowry base
A
- a proton acceptor
3
Q
what ion is dissociated when an acid is dissolved in water rather than hydroxide ions?
A
- hydroxonium ions, H3O+
4
Q
What is a conjugate pair?
A
- a pair that can be interconverted by the transfer of a hydrogen ion
5
Q
define the term strong acid
A
- completely dissociates when in solution
6
Q
what is pH?
A
- a measure of hydrogen ions in a solution
7
Q
what is the formula to work pH out?
A
- -log(conc of H+ ions)
8
Q
define the term weak acid
A
- partially dissociates when in solution
9
Q
what are a typical group of weak acids?
A
- carboxylic acids
10
Q
how do we compare the strengths of weak acids?
A
- compare the position of equilibria
11
Q
what is the acid dissociation constant, Ka?
A
- measures the position of equilibrium
- the higher the Ka the further the equilibrium position is to the right and vice versa
12
Q
do we include the concentration of water in our Kc expression and why?
A
- for weak acids, the moles of water tend to be high and they will only differ slightly to the point that it won’t make much of a difference
- water is discarded in the expression and so it is now a Ka expression
13
Q
It is hard to compare Ka values and so what is the solutions to this?
A
- we can find pKa as this would be easier to compare
- the formula for this is -log(Ka)
14
Q
What do high and low pKa values tell us?
A
- the lower the pKa, the stronger the acid
15
Q
what is the equilibrium regarding water?
A
- water can act as both acids and bases
- can lose a proton to form a hydroxide ion
- can gain a proton to form a hydroxonium ion
- this equilibrium will be happening even where there is a trace of water and that water doesn’t have to be pure
