Zusammenfassung der Ressource
GCSE AQA Chemistry 2
Salts & Electrolysis
- Acids & Alkalis
- Acid: substance with
pH less than 7, form
H+ ions in water
- Base: substance with
pH greater than 7
- Alkali: base that
dissolves in water,
form OH- ions in water
- Neutralisation: acid +
base --> salt + water
- Acids & metals
- Acid + metal
(oxide/hydroxide)
--> salt + hydrogen
- Ammonia
- Dissolves in water -->
alkaline solution
- Ammonia + Nitric acid --> Ammonium nitrate
- Ammonium nitrate - good fertiliser,
has nitrogen from 2 sources, plants
need nitrogen to make proteins
- Making salts
- Making soluble salts using
a metal/insoluble base
- Filter out excess,
evaporate & crystallise
- Making soluble
salts using an alkali
- Neutralise, repeat to remove
indicator, evaporate & cystallise
- Making insoluble salts -
precipitation reactions
- Filter salt out, wash & dry
- Electrolysis
- Splitting up with electricity
- requires electrolyte
- Contains free electrons -
conduct electricity
- Needs flow of electrons, electrons
taken away at +ve electrode &
given to other ions at -ve electrode
- Oxidation & reduction
- Oxidation Is Loss
of electrons
- Reduction Is
Gain of electrons
- Reactivity affects products formed
- At -ve electrode - if metal ions & H+ ions present,
metal ions will stay in solution if metal is more
reactive than hydrogen - keener to stay as ions
- At +ve electrode - if OH- & halide ions are present,
molecules of chlorine formed, if no halide, oxygen formed
- Electrolysis of Sodium Chloride solution produces...
- Hydrogen
- Chlorine
- Bleach & plastics
- Sodium hydroxide
- Soap
- Extraction of aluminium
- Cryolite lowers temp, & costs
- Electrodes made of carbon
- CO2 - 'eaten away'
- Aluminium forms at -ve electrode
Oxygen forms at +ve electrode
- Electroplating
- At -ve electrode - metal
object you want to plate
- At +ve electrode - pure metal