Redox Flashcards
What is redox reaction?
A redox reaction is a reaction where oxidation and reduction occurs simultaneously.
What happens in reduction? (Four things)
Oxidation state decreases
Hydrogen is gained
Oxygen is lost
Electrons are gained (negative charge)
What happens in oxidation?
Oxidation state increase
Hydrogen lost
Oxygen gained
Electrons lost (positive charge)
What is an oxidation state?
Oxidation state signifies the number of charges an atom would have in a molecule if electrons are transferred completely.
What are the o.s. of elements, oxygen, hydrogen, ions, sum in a compound, and in a molecuar ion?
Elements = zero
Oxygen (in most compounds) = –2
Hydrogen (in most compounds) = +1
Ions = its ionic charge
Sum in a compound = 0
Sum in a molecular ion = overall charge
State the answering template for redox
The oxidation state of [element] [increases/decreases] from [initial o.s.] in [reactant] to [final o.s.] in [product]. Hence [substance] is [oxidised/reduced].
What are NON-redox reactions?
Neutralisation, Decomposition, Precipitation
What are oxidising agents and examples of them?
Oxidises others, gets reduced itself
acidified potassium manganate(VII) KMnO4/H+
acidified potassium dichromate(VI) K2Cr2O7/H+
reactive halogens
oxygen, O2
[Fe]3+ salts
hydrogen peroxide, H2O2
What are reducing agents and examples of them?
Reduces others, get oxidised itself
aqueous potassium iodide, KI
Fe2+ salts
reactive metals e.g. Na, K, Ca
gaseous reducing agents, e.g. H2, SO2, CO, NH3
hydrogen peroxide, H2O2
More reactive agents make…
better reducing/oxidising agents.
How do we test for an oxidising agent? What are examples of such tests?
To test for an oxidising agent, we add a reducing agent.
Aqueous Potassium Iodide, KI: Colourless solution turns into a brown solution.
Aqueous Iron(II) Chloride, FeCl2: Green solution turns into a yellow solution.
How do we test for a reducing agent? What are examples of such tests?
To test for a reducing agent, we add an oxidising agent.
Acidified Potassium Manganate(VII), H+/KMnO4: Purple solution decolourises to become colourless.
Acidified Potassium Dichromate(VI) K2Cr2O7/H+: Orange solution turns into a green solution.
