C3.3 Flashcards
Redox reaction
Reduction and oxidation occur at the same time (in the same reaction) - reduction = loss of oxygen and oxidation = gain of oxygen.
Oxidising agent is the one that is not oxidised itself - causes the other reactant to be come oxidised
Redox in terms of electrons
Reduction is gain of electrons and oxidation is loss of electrons
What is an acid?
An acid is a substance that releases hydrogen ions when it dissolved in water to make an aqueous solution
What is a base?
A substance that can neutralise acids and if a base can dissolve in water, it is an alkali (releases OH-ions)
Oh scale
Measure of relative acidity and alkalinity
If > 7 then alkaline
< 7 acidic
0 (string acid) to 14 (string alkaline)
What is neutralisation?
Reaction between acid and a base or an alkali to form a salt and water only - salt depends on acid and base in use.
Acid + base -> salt + water
Ph changes - becomes more towards green or even over
Half equation in neutralisation reactions
H+ (aq) + OH- (aq) -> H2O (l)
Acid with carbonates?
Carbonates react with acid to create : Salt Water Carbon dioxide Most carbonates are insoluble in water (group 1 metal carbonates are soluble in water)
Acids with metals
Acid + metal -> salt + hydrogen
Dilute acid and concentrated acid
Dilute acid - has a low ratio of acid to the volume of solution
Concentrated acid - has a high ratio of acid to the volume of solution (becomes dilute when mixing it with water)
Weak acids and strong acids
Weak acids - partially ionised (only a small fraction of molecules release H+ ions)
String acids - fully ionised (all fraction of molecules release H+ ions)
If reversible symbol is used - it is a weak acid
CH3COOH (aq) ->
Ph and hydrogen ion concentration
AS HYDROGEN ION CONCENTRATION INCREASES BY A FACTOR OF 10, THE PH DECREASES BY 1
