3.1.12 Acids and bases Flashcards
What is a Bronsted - Lowry acid?
- Proton donors
- When we mix acids with water , hydrogen ions (H+) are released
What are Bronsted- Lowry bases
- Proton acceptors
- When we mix bases with water they react with H+ ions to form hydroxide ions (OH-)
What do strong bases do
Dissociate (ionise ) almost completely
What do weak bases do
Dissociate poorly
what do strong acids do
Dissociate (ionise) almost completely
What do weak acids do
Dissociate poorly
What is an example of a weak acid and some information about it
- Ethanoic acid and other carboxylic acids
- Backwards reaction favoured so not many H+ (protons) produced
What are some examples of a strong acid and some information about it
- HCl (hydrochloric acid)
- H2SO4 ( Sulfuric acid)
- HNO3 ( nitric acid)
Forwards reaction favoured strongly . Lots of H+ produced
What are examples of a strong base and some information about it
NaOH ( sodium hydroxide )
KOH ( potassium hydroxide)
Forward reaction favoured strongly . Lots of OH- ions produced
What is an example of a weak base and some information about it
NH3 ( ammonia)
Backwards reaction favoured so not many OH- ions produced
What happens when acids and bases react with each other
Protons are exchanged
What does water do when acid is added to it
Acts as a base (accepts a proton)
What is the Kc equation to represent water
[H+][OH-] / [H2O]
What can water dissociate into and what is the equation to show this
Water dissociates into OH- ions and H+ ions
H2O (reversible reaction) H+ + OH-
What is Kw?
Ionic product of water
What are the units for Kw?
mol^2dm-6
what is the expression for Kw
[H+][OH-]
What is the value of Kw
1.00 x10^-14 mol^2dm^-6
When does the value of Kw change
When temperature changes
- Value of Kw is the same in a solution at a given temperature
What concentration of OH- ions and H+ ions does pure water have
The same concentration of H+ and OH- ions.
What is the expression for pure water
Kw = [H+]^2
What is pH
Is a logarithmic scale that measures the concentration of H+ ions in solution
What is the pH equation
pH = -log10[H+]
What is the equation to work out H+ ions from pH?
[H+] = 10^-pH
(press shift then log for the 10)