Acids, Bases And pH Flashcards
Brønsted-Lowry bases are….
Proton acceptors
A bronsted- Lowry acid is…
A proton donor, release hydrogen ions when mixed with water
Acid-base equilibria involves…
The transfer of protons
Info on strong acids and bases in water
Strong acids can almost completely dissociate in water (nearly all the Hydrogen ions are released) eg HCl. Eqm lies to right
Strong bases ionise almost completely in water. Eqm lies to right
Info on weak acids and bases in water
Weak acids dissociate only very slightly, only small number of H+ ions formed. Eqm set up which lies to the left
Weak bases only slightly dissociate in water, eqm to left
What are transferred when acids and bases react
Protons
What does water dissociate into
Hydroxonium ions and hydroxide ions
The pH scale is a measure of what
The hydrogen ion conc
By how much does water dissociate
Only very slightly
What does monoprotic mean, give 2 examples
Each molecule of an acid will release 1 proton when it dissociates
Eg HCl and HNO3
Example of a diprotic acid
Sulphuric acid
What happens to weak acids and bases in aqueous solutions
They dissociate only very slightly
What things can you do to make your titration results accurate
Measure neutralisation volume as precisely as possible (usually to nearest 0.05cm3)
Repeat at least 3 times, take mean average = reliable
Don’t use anomalous results
What do diprotic acids do
They release 2 protons when it dissociates
What is a buffer
A solution that resists changes in pH when small amounts of acid or alkali are added
What the 2 types of buffers
Acidic and basic
What are acidic buffers made from
A weak acid and one of its salts
What are basic buffers made from
A weak base and one of its salts
Uses for buffers?
Shampoos- most contain pH 5.5 buffer, it counteracts the alkaline soap in shampoo
Biological washing powders- keep pH at right level for enzymes to work best
Lots of biological buffer systems in bodies, making sure our tissues are kept at right pH. Eg its vital that blood stays at a pH very near to 7.4 so it contains a buffer system
Why is ethylamine a stronger base than ammonia
The alkyl group is electron donating
There is increased availability of the lone pair
Why is chloroethanoic acid stronger than ethanoic acid
Cl is more electronegative so weakens O-H bond more
