Chemical Changes Flashcards
Why is a pipette used to measure alkali and burette used to measure acid?
Pipette measure fixed volume
Burette measures variable volume
Reaction between acids and bases is called
Neutralisation
Acid is a substance that forms? Water?
Aqueous solutions
H+ ions in water (ionises)
pH > 7
Alkali are…
Bases
Bases dissolve in water to form?
OH- ions
pH < 7
“acid + base” produces…
salt + water
Phenolphthalein, alkali —> acid
pink —-> colourless
Properties of weak acids
- Do not fully ionise in solution
- Only a small proportion of acid particles dissociate to release H+ ions
- Reversible reaction
- Less reactive than strong acids
Properties of Strong acids
- Ionises completely in water
- All acid particles dissociate to release H+ ions
- More reactive than weak acids
H+ ion concentration high mean…
A strong acid so
rate of reaction is faster.
Concentration is the measure of….
how much acid is in a certain volume of water
Reactivity is determined by…
how easily a metal loses an electron
Acid + Metal Carbonate ——>
Salt + Water + Carbon Dioxide
Acid + Metal ——->
Salt + Hydrogen
Zinc, Iron and copper can be extracted by reduction
Using Carbon this is because oxygen can only taken from metals which are less reactive than carbon,
Oxidation is the
OIL
Gain of oxygen
Loss of electron
Reduction is the
RIG
Loss of oxygen
Gain of electron
What is an electrolyte?
A molten or dissolved ionic compound
Positive Ions in electrolyte move to
the Cathode ( negative electrode) they gain electrons! :)
Negative Ions in electrolyte move to
the Anode (positive electrode) they lose electrons! :(
Positive metal ions are
Reduced
