Chemical Changes Flashcards
Acid definition
Any substance that forms an aqueous solution with ph 7 or less
They ionise in aqueous solutions, releasing H+ ions
Bases definition
Any substance that can neutralise an acid
Common examples of bases:
- Naked metals
- Metal Oxides
- Metal Hydroxide
- Metal Carbonates
Alkalis are an example of __________ bases
soluble
How are salts formed?
When the hydrogen ions in an acid are replaced with metal or ammonium ions (in a neutralisation reaction)
Alkalis are compounds that release _____ when dissolved in water
OH- ions
Sulfuric acid
H2SO4
Nitric acid
HNO3
Hydrochloric acid
HCl
whereas strong acids completely ionise in aqueous solutions, with weak acids…
only a small percentage of their molecules split up into ions
Neutralisation
when an acid and base react to give salt + water
acid + metal ->
salt + hyrdrogen
acid + metal oxide ->
salt + water
acid + metal hydroxide ->
salt + water
acid + metal carbonate ->
salt + water + carbon dioxide
During a neutralisation reaction, the positive hydrogen ions from the acid react with the negative ___________ ions from the ____________
- hydroxide
- alkali
Strong acids _________ completely, so all of the acid particles will _______ to release ___ ions in aqueous solutions
- ionise
- dissociate
- Hydrogen
Examples of strong acids
hydrochloric acid
sulfuric acid
nitric acid
symbol: hydrochloric acid
HCl
symbol: sulfuric acid
H2SO4
symbol: nitric acid
HNO3
In aqueous solutions, only a _______ proportion of the acid particles ______.
- small
- dissociate
Ionisation of a weak acid is….
REVERSIBLE
Examples of weak acids
Ethanoic Acid
Citric Acid
Carbonic Acid
The higher the concentration of hydrogen ions, the _______ the pH
lower
pH scale = the concentration of…
H+ ions
REDOX -
oxidation and reduction simultaniously
Oxidation
lose electrons
gain oxygen
Reduction
lose oxygen
gain electrons
ionic equations will only show the particles that…
take part in the reaction and change in some way from left to right… write them out with their charge specified i.e. make it obvious that they are ions.
Half equations are the ionic equation but only showing the change of…
1 element