Redox Reactions Flashcards
Define redox reaction
Redox reaction is a reaction where oxidation and reduction occur at the same time
Define oxidation/reduction in terms of oxygen
Gain/Loss of oxygen by substance (with no other changes to the substance)
Define oxidising agent
A substance that oxidises another substance while itself is being reduced
Explain oxidising agent in CO(g) + H2O(g) reaction in terms of oxygen
H2O is the oxidising agent as H2O loses oxygen to CO and oxidises CO to CO2
Define oxidation/reduction of substance in terms of hydrogen
Loss/Gain of hydrogen by substance(with no other changes to the substance)
Explain reducing agent in reaction Cl2(g) +H2S(g) in terms of hydrogen
H2S is the reducing agent because H2S loses hydrogen to Cl2 and reduces Cl2 to HCl
Define oxidation/reduction in terms of electrons
Loss/Gain of electrons by substance
Define oxidising agent in reaction Na(s) + Cl2(g) in terms of electrons
Cl2 is the oxidising agent as Cl2 gains electrons from Na and oxidises Na to Na+
Define oxidation state/oxidation number
The charge an atom would have if it existed as an ion
Define electronegativity
The ability of an atom to attract the shared pair of electrons towards itself in a covalent bond
How does electronegativity vary in a group and period
Increase across a period decrease down a group
Arrange following in terms of electronegativity: Br, N, F, O, H, C, Cl, I
F, O, Cl, N, Br, I, C, H
Define oxidation/reduction in terms of oxidation state
The increase/decrease in oxidation state of an element in a substance during a reaction
Explain substance which is reduced in Mg + CuO in terms of oxidation state
CuO is reduced because the oxidation state of copper decreases from +2 in CuO to 0 in Cu
Why is HCl + NaOH not a redox reaction
The oxidation states of all elements in the substances remain unchanged during the reaction
Observation for acidified aqueous potassium manganate(VII)
Purple acidified aqueous potassium manganate(VII) turns colourless (testing reducing agent)
Observation for aqueous potassium dichromate(VI)
Orange acidified aqueous potassium dichromate(VI) turns green (testing reducing agent)
Observation for aqueous iron(III) chloride
Yellow aqueous iron(III) chloride solution turns pale green (testing reducing agent)
Observation for aqueous iodine
Brown aqueous iodine turns colourless (testing for reducing agent)
Observation for aqueous potassium iodine
Colourless aqueous potassium iodide turns brown (black solid may be formed if excess iodine is formed) (testing for oxidising agent)
Observation for aqueous iron(II) sulfate
Pale green aqueous iron(II) sulfate turns yellow (testing for oxidising agent)
Define disproportionation reaction
A reaction where a single substance is both oxidised and reduced in the reaction
